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Milk Pasteurization Training Manual 8th Edition

1. D 2 loga log b Where D 2 Time in seconds at a given temperature for 9096reduction in bacteria in whole milk n process temperature t equivalent holding time at a process temperature log a the initial bacterial population per m I log b the survivor concentration per m 28 BACKGROUND AND HISTORY By plotting different D values on semi log paper a straight line curve may be obtained The slope of this line in the Z value of an organism This value relates directly to the temperature increase that effects a ten fold reduction in holding time while maintaining the same lethality of the process For example the figure below using 01200 8 minutes a reduction of from 10 000 ml to 0 0001 ml 1 10 000 ml is equivalent to 8 log reduction or 99 999999 reduction of organisms Studies on the heat resistance of pathogens were used in arriving at the D Value necessary to assure safe and acceptable levels in the pasteurized product Escherichia coli as an example which is one of the more heat resistant of the coliform organisms was isolated after thermal process of 76 7 C 169 8 F with an initial concentration of 2 X 10 ml and the survivor rate was 10 ml 1 1 000 ml From these values a D Value of 0 246 can be established for the Escherichia coli organism In the early 1920 s when Ball and others were establishing procedures for calculating thermal processes the observation was ma
2. Age rand now PRINCIPLES OF OPERATION TRI CLOVER INCIPLES OF OPERATION 9 4 H FLOW DIVERSION Divert Flow Leak Detector Flow Forward Flow 105 Figure 24 Dual Stem Devices and Function 2 Operation a Each manufactured brand of valve is slightly different in design however all have two bodies with an interconnecting yoke pneumatic actuators and spring loaded valve plungers b All are designed to move to and or to remain at the fail safe divert position in the event of loss of adequate temperature electronic power air pressure c Each valve is actuated by a non restricted quick exhaust type solenoid valve that controls the air to each valve d Micro switches are located near the top of each actuator stem in the valve bonnet and operate and function identical to those in the single stem flow diversion device Control power signal to the timing pump frequency pen and panel indicator lights MICRO SWITCH ROLLER lt ACTUATOR STEM SET ROLLER IN BOTTOM OF GROOVE WHEN VALVE IS IN THE DIVERT POSITION 106 Basic HTST Pasteurization Recently introduced into the market under memorandum from the FDA Milk Safety Branch is the new Tri Clover Flo Diversion Valve and Panel Model 762 227 MRAL Reverse Acting FDD This valve operates similar to previous models other than it is horizontally mounted which eliminates most hydraulic shock in systems where the
3. Note The effectiveness of this system shall be evaluated by disconnecting the milk inlets to the the vacuum system with maximum vacuum and while the system is in diverted flow and inspect the piping to the vacuum system for negative pressure 3 When vacuum equipment is located downstream from the flow diversion device the holding time shall be tested with the timing pump operating at maximum capacity and the vacuum equipment operating at maximum vacuum 4 When culinary steam is introduced into the product downstream from the flow diversion device means shall be provided to prevent the addition of steam unless the flow diversion device is in the forward flow position This shall include an automatic steam control valve with a temperature sensor located downstream from the steam inlet or an automatic solenoid shut off valve installed in the culinary steam line These controls must be wired through 161 the flow diversion device so as to stop the introduction of steam when the flow diversion device moves to the diverted flow position or during periods of loss of power or shut down 5 Steam used in contact with product shall be of culinary quality Only those boiler compounds that comply with 21 CFR Part 173 310 Boiler Water Additives shall be used 162 STEAM PRESSURE REGULATING REDUCING VALVE STEAM THROTTUNG VALVE AUTOMATIC OR MANUAL CONDENSATETRAP tS m si AND CONNECTION FILTER Adams
4. 05 1986 Fultonville NY Anderson Instrument Co Inc Anderson Model 700 RTD Input Recorder Bulletin No 22 Fultonville NY Carson R B Undated paper History of Milk Sanitation Milk Pasteurization Controls and Tests manual 1st edition State Training Branch USPHS Cherry Burrell Flow Diversion Device Instruction Manual Cedar Rapids IA 1978 Crombie R A Paper dated 4 82 Pumps and Electrical Controls Illinois Department of Public Health Custom Control Products Product pamphlet Electronic FDV Controller 1991 Racine WI Dickerson Scalzo Read and Parker Residence Time of Milk Products in Holding Tubes of High Temperature Short Time Pasteurizers Journal of Dairy Science Vol 51 No 11 Pages 1731 1736 Des Moines Iowa 1968 FDA Pacific Region Dairy Products Team Guidelines for Conducting PMO DMO Equipment Tests and Reporting Results Memorandum June 25 1998 Freedman B 1977 Sanitarians Handbook Fourth Edition Peerless Publishing Co New Orleans LA G amp H Products Instructions Clean in Place Flow Diversion Model GC60FDV Bulletin GH2003 SRC FD Model Flow Diversion Device Instruction Manual amp Parts List Kenosha WI 1979 343 Grade A Pasteurized Milk Ordinance U S Department of Health and Human Services Public Health Service Food and Drug Administration 1995 Revision Washington D C Haskell W H F J Moss H E Eagan History of Milk Sanitation Mimeographed Paper
5. Honeywell Inc Process Control Division Product Manual 44 45 25 13 Honeywell Truline Recorder Controllers M b 312 March 15 1991 Fort Washington PA Hsu David S Ultra High Temperature Processing and Aseptic Packaging of Dairy Products 1970 Damana Tech Inc New York N Y Jordan W K R P March Fluid Dynamics and Heat Transfer 1958 Mcgraw Hill NY Ladish Company Tri Clover Flow Diversion Valve Model 262 121 Tri Clover Positive Rotary Pump Catalog PR 73 1978 3 A Sanitary Standards International Association of Food Milk and Environmental Sanitarians Des Moines Iowa Sims Steven T Food and Drug Administration Milk Safety Branch Memoranda Information and Handouts provided at Special Problems in Milk Protection Course 510 andThe Advanced Workshop in Milk Processing 511 July August 1996 Stroup W H Dickerson R W Jr Thompson H E Jr 1972 Steam Injection Pasteurization of Grade A Milk and Milk Products Food and Drug Administration Washington D C Taylor Instrument Companies Taylor Sanitary Pressure Indicator with Differential Pressure Switch 117K 447K Instructions IB 3B202 and IB 3B203 Rochester NY Westoff D C Heating Milk for Microbial Destruction A Historical Outline and Update J Of Food Protection Vox 41 No 2 February 1978 IS OK E E a 344 Note The use of trade names or equipment photographs is for training and educational purposes only and does
6. RECIRCULATION LINE e Na HOMOGENIZER 2 RECYCLE LINE 1 1 CHECK VALVE t REGENERATOR tS NORMALLY CLDSED i RAV BY PASS VALVE amc HE 5 lt 6 MAGNETIC DRAIN FLOW METER i e BOOSTER PUMP 65 i i i VARIABLE SPEED Figure 55 Meter based system with AC variable speed drive 1 this line shall be at least 12 inches above any raw product piping the HTST system 2 all divert leak detection and recycle lines which return to the constant level tank must break to atmosphere at lest two pipe diameters above the over flow level 3 the overflow level of the constant level tank must be lower that the bottom of the inlet of the raw regenerator 5 required if homo is greater capacity than timing pump 6 regenerator bypass valves must be installed to be drainable and must prevent dead ends or be drilled A drilled check valve may be used between inlets of booster pump and timing pump Air operated valves must be normally open automatically operated and controlled to open if timing device stops 8 straight pipe per manufacturers recommendations required on both sides of the centerline of the magnetic flow meter Meter shall be located so electrodes are flooded No product can enter or leave the system between the centrifugal timing pump and the flow diversion device The flow control valves if used shall be normally closed air to open This valve may be replaced with a sa
7. Method By observing when the piping is disconnected from the valve outlet whether or not leakage past the valve seat occurs when pressure is exerted against the upstream face of the valve Procedure 1 During normal operation while milk pressure is exerted against the valve inlet fully close the outlet valve and disconnect the outlet piping Caution care must be taken to avoid contamination of the valves or the piping 2 Observe whether or not any milk is leaking past the valve seat into the valve outlet 3 Turn the valve to the just closed position and examine the leakage into the valve outlet 4 Reconnect the outlet piping 5 Record identity of the valve and findings for office record Corrective Action If leakage past the valve seat should occur in any closed position the valve plug should be reground gaskets replaced or other necessary steps be taken to prevent leakage 261 TEST 7 INDICATING THERMOMETERS ON PIPELINES THERMOMETRIC RESPONSE Reference Item 16 Application To all HTST indicating thermometers located on pipelines and used for determination of milk temperatures during pasteurization Frequency Upon installation and once each 3 months thereafter and whenever the seal on a digital thermometer has been broken Criteria Four seconds under specified conditions Apparatus Stopwatch water bath agitator heat supply and indicating thermometer from pasteurizer Method By m
8. The booster pump may be operated by the plant computer ONLY IN THE CIP MODE Its operation must be interfaced through the flow diversion device control panel If the booster pump has an address which it will in the computer key it up If the Output red light is on and blinking then examine whether it is actually operating It shouldn t in the PRODUCT mode It may run in the CIP mode TIMING PUMP The timing pump may be operated by the plant computer only if the flow diversion device is properly assembled and only in the PRODUCT OR CIP MODE NEVER IN THE INSPECT MODE STUFFING PUMP Stuffing pumps may be operated by the plant computer at any time the timing pump may be allowed to operate SEPARATOR BY PASS VALVES a Pasteurized separator by pass valves may not be operated by the plant computer during diverted flow b Raw product separator by pass valves may not be operated by the plant computer when the timing pump is not running FLOW DIVERSION VALVE Flow diversion valves may be operated by plant computer only in the CIP mode Flow diversion device microswitches must not be controlled directly or overridden by the computer There shall be no output override switches on the Output bus 365 6 MANUAL DIVERT There are no direct wiring connections operable by the plant computer to the flow diversion device i e FORCE ON or FORCE OFF capabilities 7 COMPUTERIZED PUBLIC HEALTH CONTROLS ROMS and PROM
9. Whole Milk F for sec b Cream F for sec c Skim F for sec d Eggnog F for sec 3 Trace the basic flow through an HTST pasteurizer by placing the correct numerical in ascending order Holding tube Heater section ____ Vacuum breaker To filler or storage Cooler section Metering pump Constant level tank side of regenerator Flow diversion device Recording thermometer sensor Pasteurized side of regenerator Indicating thermometer 4 Explain regeneration as it is normally applied to continuous pasteurization 171 5 The official thermometer on any pasteurizer is the The a recording b indicating thermometer must be located within c 12 d 18 inches of the flow diversion device Circle the correct choice 6 What is the purpose of maintaining an upward slope on the holding tube 7 Where does the timing pump get its power from in diverted flow 8 Four functions served by the balance tank are 1 2 3 4 9 Describe the methods of pressure controls utilized on a basic HTST system 10 What is the purpose of the small drilled hole in the milk to milk regenerator deflector plate s 11 Why are we concerned about holding times for milk when the flow diversion device is in the diverted position 12 Flow diversion devices are activated into forward flow and operated to the diverted position 13 Quick disconnects are allowed only on those flow diversi
10. 1 IF Lz 4H AND LXH2 02 THE BOTTOM OF THE OPENING MAY BE TAKEN AS THE FLOOD LEVEL 2 IF THE CONDITIONS OF NOTE 1 ARE MET AND H2 2D THE VENT ON THE TOP OF THE TANK MAY BE ELIMINATED BALANCE TANK LID BALANCE TANK ELEVATED SIDE BRIDGE gt MILK Z gt REGENERATOR d DIAMETER OF LARGEST RETURN PIPELINE NOTE 1 COVER MUST BE LIGHT ENOUGH TO BE LIFTED BY OVERFLOW AT FLOOD LEVEL lt d OR LARGER 2 OR ors NOTE 1 EA FLOOD OR LARGER 2d OR LARGER d DIAMETER OF RETURN PIPELINE D DIAMETER OF LARGEST SUPPLY PIPELINE NOTE 1 COVER MUST BE LIGHT ENOUGH TO BE LIFTED BY OVERFLOW AT FLOOD LEVEL 66 Basic HTST Pasteurization B THERMAL EXCHANGE SYSTEMS 1 Plate Heat Exchangers a Sanitary design and construction b General sections are 1 heating 2 cooling 3 regeneration c Flow patterns d Proper maintenance and inspection Controls Figure 9 Plate Heat Exchanger Frame Press 67 HOT PASTEURIZED MILK FROM HOLDING TUBE PASTEURIZED MILK TO COOLING SECTION re RAW MILK FROM RAW MILK TO TIMING TANK PUMP DEFLECTOR PLATE RAW DRILLED Figure 10 Plate Heat Exchanger Flow Patterns 68 Basic HTST Pasteurization 2 Tubular Heat Exchangers a Sanitary design and construction The interior of these pipe in a pipe regenerators must be smooth and cleanable a
11. ___ To properly test for response time simply start the stopwatch when the display reads temperature 12 degrees below the cut in temperature If the display moves too quickly or skips over the start temperature you may start the watch at a temperaure 2 3 degrees below the desired temperaure The result should be well within the 5 second maximum Stop the watch when the display changes from 314 STLR OUR OFF to OUT ON Test 10 Milk Temperature at Cut in and Cut out These tests may be performed as outlined in the PMO If a change is required to the cut out temperature or to the amoujnt of dead band between cut in and cut out proceed as follows 1 Remove the regulatory seal and open the chart plate Reposition the security shunt to the Program mode as outlined above 2 Press the SCROLL Key until the display reads SELECT CONTROLLER SETUP 3 Press the the DOWN Arrow Key STLR will be flashing in the lower left display 4 Pressthe button below the flashing STLR 5 Pressthe scroll key until the display reads the appropriate set point 1thru 5 The displayed setpoint is the cut out value If you wish to change the setting press the MOD Key This will underline the value Then use the UP DOWN keys to modify 6 Press the ENTER KEY to program the new value 7 Pressthe skoll dey again to display the aount of deadband between Cut in and Cut out for that set point Each set point will have i
12. 172 METER BASED TIMING SYSTEMS b The electric voltage signal generated is directly proportional to the velocity of the conducting product This signal is detected by the 316 SS or equivalent electrodes sensors installed within the internal pipe of the flow meter installed vertical c This alternating signal is relayed to the electronic components of the meter based system These components are comprised of an electrical transmitter a transducer converts an electronic signal to a pressure value a flow recorder controller d The product velocity is controlled by either a flow control valve or an AC drive variable speed centrifugal product pump e These components receive the generated signal from the magnetic flow meter process the information and control the flow of the product through the system 173 On the following page illustrations of both a magnetic flow meter aow control or throttling valve used in milk systems is provided amp ACTUATOR ACTUATOR CLAMP COUPLING NS C BODY CLAMP GASKET f LOWER BODY VALVE PLUG ASSEMBLY seni AIR ACTUATED THROTTLING VALVE TRI CLOVER FIGURE 53 174 METER BASED TIMING SYSTEMS FLOW CONTROL VALVE AND METER 175 APPLICATION IN HTST SYSTEMS Magnetic flow meter systems are used to replace the conventional tim
13. APPLICATION to all Taylor recorder controllers used in connection with continuous flow pasteurizers FREQUENCY Upon installation and once every three months thereafter CRITERIA Forward flow cannot occur until the minimum pasteurization temperature has been reached Diverted flow must occur before the temperature drops below the minimum pasteurization temperature APPARATUS Indicating thermometer that has been calibrated with a thermometer traceable to or certified by the National Bureau of Standards and a means of changing temperature in the holding tube or water bath or oil bath at a rate not exceeding 1 F every 30 seconds METHOD Observe the actual temperature of the indicating thermometer at the instant the flow diversion device moves to the forward flow position cut in and the flow diversion device movesto the diverted flow position cut out PROCEDURE Same as for conventional STLR CORRECTIVE ACTION If the cut in or cut out temperature is lower than the minimum pasteurization temperature raise the low alarm setting on the ER C recorder controller according to the procedures outlined in Test A Programming of Process Values Repeat the test 318 TEST D LOCKING AND SEALING OF INSTRUMENT APPLICATION To all earlier model not for 5100 series Commadore models Taylor ER C recorder controllers used in connection with continuous flow pasteurizers FREQUENCY Upon installation every three months therea
14. An electrically erasable programmable read only memory The entire memory is erased with one electrical signal EPROM An erasable programmable read only memory The entire memory is erased by exposure to ultra violet light Fail Safe Design considerations that cause the instrument or system to move to the safe position upon failure of electricity air or other support systems Field alterable A device having a specific design or function that is readily changed by user and or maintenance personnel Force off A programmable computer instruction that places any input or output in the off state independently of any other program instructions 357 Force on A programmable computer instruction that places any input or output in the on state independently of any other program instructions Input A data set applied to the input bus of the computer that is used by the computer to make logical decisions on whether or not to activate one or more outputs Input consists of data from temperature and pressure instruments liquid level controls tachometers microswitches and operator controlled panel switches Input Output bus An electrical connection panel that provides for the connection of all inputs and outputs to the computer The input output address labels are found on the panel Indicator lights showing the status on off of all inputs and outputs are usually available on this panel Last state switch A manually oper
15. Controls a The timing pump must be sealed by the regulatory authority at the maximum speed to assure that the minimum holding time requirements are satisfied b It must also be inter wired with the flow diversion device and recorder controller This is to prevent the sub legal flow of milk into the pasteurized side of the system c Generally there is only one primary timing device in system When both a positive displacement pump and homogenizer are used as timing pumps both must be timed separately and together to assure minimum holding times are achieved D HOLDING TUBE 1 It must be of sanitary design 2 It must be installed on permanent supports to assure alignment and proper slope and pipe size changes shall be properly designed and installed 3 The entire length of the holding tube must be properly slope to preclude air entrapment and assure uniform product flow The minimum upward slope is 0 25 inch per running foot or 2 1 centimeters per meter 4 t must be fabricated to eliminate short circuiting no alterable sections 5 The holding tube starts at the salt injection port or fitting and ends at the flow diversion device 72 Basic HTST Pasteurization Figure 13 Holding Tube Installation 6 Holding tubes must be designed to assure temperature variation not to exceed 1 7 Heat shall not be applied to the holding tube at any point and the holding tube shall not be fitted with insulation materi
16. FOR CONTROL SEQUENCE LOGIC References Items 16p B 16p E Thermal limit controllers used with HHST and aseptic processing systems that have the flow diversion device located downstream from the regenerator and or cooler shall be tested by one of the following applicable tests at the frequency specified 12 1 HHST PASTEURIZATION AND ASEPTIC PROESSING INDIRECT HEATING 305 Application To all HHST and aseptic processing systems pasteurizers using indirect heating When testing aseptic processing systsems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in thei test Frequency Upon installation and every 3 months thereafter or when a regulatory seal has been broken Criteria The pasteurizer or aseptic processing equipmentshall not operate in forward flow until the product surfaces downstream from the holding tube have been sanitized or in the case of aseptic processing equipment sterilized On start up surfaces shall be exposed to fluid at pasteurization or is the case of aseptic processing equipment sterilization temperature for at least pasteurization or sterilization time If the product temperature falls below the pasteurization or sterilization standard in the holding tube forward flow shall not be re achieved until the product surfaces downstream from the holding tube have been re sanitized or is t
17. NO position which the flow diversion device solenoid which allows air at approximately 40 psi to compress down on the diaphragm and spring moving the flow diversion device to the forward flow position Therefore in FORWARD FLOW the timing pump is solely energized through the recorder controller micro switch 80 Basic HTST Pasteurization Conversely as the temperature decreases to below the diversion set point cut out this allows the Bourdon coil to retract and air to escape through the nozzle releasing the air from the capsular chamber allowing the push rod to move to the left which allows the micro switch to assume the normally closed NC position This action de energizes the flow diversion device air solenoid preventing air from depressing the diaphragm and spring in the FDD assuring DIVERTED FLOW Because of the design of the recorder controller i e pneumatically driven to the right cut in and spring driven to the left cut out and the delay necessary for the capsular chamber to depressurize the cut in temperature will normally be slightly higher than the cut out temperature on mechanical capillary driven recorder controllers This differential temperature may be adjusted to suit operator and plant standards but both cut in and cut out MUST be higher than the required minimum pasteurization temperatures Electronic STLR s diversion differentials are pre set at the factory and are usually 1 1 degrees
18. One is the gear driven type pump where two rotors or impellers revolve within an oval case Close tolerances between the gears and the outer case make the space or pockets between the teeth or lobes carry the fluid around the periphery of the pump body The size of these pockets and the speed at which they revolve determine the volume that will be pumped It is important to remember that the efficiency of these impeller type pumps may be greatly influenced by the temperature and type of liquid they are pumping This becomes important when performing the holding time water milk tests and calculations for systems with these type PD pumps 70 Basic HTST Pasteurization During operation the gears are lubricated by the fat in the product The impellers must be disassembled at the end of each operating period and manually cleaned and should be lubricated with a sanitary lubricant when reassembling Figure 12 Positive Displacement Rotary Pump Function _ E b Another type pump frequently used is the belt pulley driven piston type pump such as the homogenizer Homogenizers are very efficient positive displacement pumps and are frequently used as the timing pump in continuous pasteurizers c The other type of acceptable timing pump is magnetic flow meter based system which uses a centrifugal pump in conjunction with product flow controlling methods These systems will be discussed in Chapter V Meter Based Systems 3
19. and so identified for the type of recorder being used e On those vats used solely for pasteurizing at temperatures greater than 160 the recording chart may be graduated in 1 C 2 The 1 2 F increments shall be in the 150 to 170 F range On these type vats the chart may be graduated in 15 minutes for a maximum of 24 hours The recorder device may be either electric or spring driven Required recorder chart information for each product batch 1 Name of milk plant 2 Date 3 Signature or initials of the operator 4 Identification of the recorder when more than one vat is 5 Record of holding time including empty and fill times as 6 Reading of air space thermometer at the beginning of the 7 Reading of indicating thermometer at an indicated point 8 Amount and name of product represented by each batch 9 Record of any unusual occurrences Charts shall be retained for 3 months 46 VAT PASTEURIZATION gt 1992 2 3 4 5 7 m m 12 15 ns T 8 m 22 21 22 23 24 25 25 27 28 29 30 31 47 VAT PASTEURIZATION 5 Air space heaters may be necessary to maintain minimum air space temperatures These devices must be of sanitary design meet all 3 A Sanitary requirements inclu
20. been 1 recognized by the Food and Drug Administration to be equally fail safe accurate reliable and meet the scale and thermometric response specifications and 2 which are approved by the regulatory agency 2 Water or oil bath or other suitable heating media to within a range of 2 C 3 F of the appropriate pasteurization or airspace temperature or aseptic processing temperature 3 Suitable means of heating the water or oil bath 237 Method Both thermometers exposed to a water or oil medium of uniform temperature Indicating thermometer reading is compared to the reading of the test thermometer Procedure 1 Prepare a quantity of water in milk can or a quantity of oil in an oil bath or a quantiy of other suitable heating media by raising the temperature of the water or oil or other suitable heating media to within a range of 2 C 3 F of the appropriate pasteurization or aseptic processing temperature or airspace temperature 2 Stabilize the bath temperature and agitate the water or oil bath rapidly 3 Continuing agitation insert the indicating and test thermometers to indicated immersion point 4 Compare both thermometer readings at the appropriate pasteurization or aseptic processing temperature within the test range 5 Repeat comparison of readings 6 Record thermometer readings thermometer identification or location 7 Install seals as appropriate on sensors and control boxes of digital thermomete
21. c Cut in and cut out temperatures d Locking and sealing of instrument Testing of ERC s will be discussed in the testing section of this manual On the single diversion models the red pen records the temperature and the blue pen is the event pen that records the position of the flow diversion device On the dual diversion models there is a green pen that records the diversion temperature selected 87 How do they work A4to 20 milliamp mA signal is provided on the red pen to drive 5 5 mA low alarm for the dual diversion instrument b The RTD sensor device is installed in the normal position at the end of the holding tube The product temperature is sensed by the 1 4 inch diameter platinum quick response tip converted to 4 20mA signal within the terminal block and relays this signal to the ERC d The ERC automatically records the value transmitted and provided the values are at or above the set low point legal pasteurization temperature the flow diversion device solenoid in energized This allows air to pass to the diaphragm thereby placing the flow diversion device in forward flow Flow diversion valve solenoids may be either electro mechanical or electric switches or relays 4 Recorder Specifications a Must be electrically operated The chart scale not less than 30 F including the set diversion temperature and at least 12 F It shall be graduated in 1 F divisions at least 1 16 in apart at the
22. slowly decrease flow rate d Start the stopwatch the instant the frequency pen on the Flow Recorder indicates the start of a forward flow movement e Stop the stopwatch the instant the flow diversion device starts to move to the forward flow position f Record results for the office record g Install and seal enclosure over the time delay relay Corrective Action If the time delay is less than the minimum holding time increase the time setting on the time delay and repeat this test procedure 11 3 CALCULATED HOLD FOR INDIRECT HEATING Application To all HHST pasteurizers using indirect heating Frequency When installed and semiannually thereafter whenever seal on speed setting is broken whenever any alteration is made affecting the holding time the velocity of the flow e g replacement of pump motor belt driver or driven pulley or decrease in number of heat exchange plates or the capacity of holding tube whenever a check of the capacity indicates a speedup Criteria Every particle of product shall be held for the minimum holding time in both the forward and diverted flow positions Apparatus No supplemental materials needed Method Fully developed laminar flow is assumed and holding tube length is calculated An experimental determination of pumping rate is required this is accomplished by determining the time required for the pasteurizer to fill a vessel of known volume converting these data by division to obta
23. AA position Turn regulator A until the pressure gauge on the CDT reads 40 psi both sensors should also read 40 psi within of scale division Turn regulator A to the left until all of the air is released both sensors should read 0 psi within of scale division HTST DIFFERENTIAL PRESSURE CONTROLLER TEST Taylor Model s 2117 and 447K Place the selector in the AB position Turn regulator A and regulator B to the right until the plants differential pressure controller DPC reads 40 psi for both pointers 3 Depress the test or over ride button on the DPC and simultaneously adjust regulator A to the right increasing the air pressure on the pasteurized sensor until the pasteurized pressure has increased a minimum of one scale division The DPC indicator light should go on 4 Gradually no faster than 1 psi per 5 seconds decrease the pasteurized sensor air pressure by turning regulator A to the left At the point when the indicator light goes off note the pressure differential on the plants DPC This is recorded as the official tested PRESSURE DIFFERENTIAL 273 5 Quickly release all air pressure from both sensors until both sensors on the DPC read 0 psi 6 Repeat test 3 The pressure differential should be identical at 0 psi and 40 psi Note A suitable test light or voltage meter across two leads from the magnetic starter may be used to test booster pump on and off operation 9 2 2 HTST INTERWIRING OF TH
24. AND CONTROLS Milk enters the system at the balance tank which is interlocked with a auxiliary CIP FLUSH tank Water is usually directly connected to this tank using an acceptable block and bleed type valving arrangement which prevents accidental contamination of the product The water line is also protected from back siphonage by using an approved pressure type back siphonage protection device Product is then fed by a centrifugal pump to a preheater usually a plate type which uses hot water as the heat transfer medium This isthe first milk to water regenerator In this regenerator the raw milk should be under lower pressure than the heat transfer medium This prevents contamination of the pasteurized product which will be discussed later The product then proceeds to a positive pump which feeds the sterilizer chamber This chamber is actually a steam infusion chamber whereby the product is introduced into a steam atmosphere 218 HHST UP AND UHT SYSTEMS This process involves the introduction of culinary steam into the product within a falling film type vessel or chamber These systems must also meet all applicable requirements of the Ordinance as covered in the above sections In some of these infusers the product is fed into the chamber inside two feed tubes connected to the side of the chamber Each feed tube consists of a tube within a tube having small drilled holes on top and the outer tube has a 3 16 inch wide slit
25. CONTROLLER WITH THE FLOW DIVERSION DEVICE IN AN HHST SYSTEM OR AN ACCEPTABLE ALTERNATIVE DEVICE OR SYSTEM IN ASEPTIC PROCESSING EQUIPMENT Application To all differentail pressure controllers used to control the operation of flow diversion devices on HHST systems when no vacuum breaker is located downstream from the holding tube and b To all differential pressure controllers used to control the operation of flow diversion devices product divert systems product divert valve s or other acceptable control systems used in aseptic processing equipment Apparatus A sanitary pressure guage and a pneumatic testing device described under PRESSURE SWITCHES Test 9 1 above can be used for checking and adjusting the differential pressure switch setting Method The differential pressure switch is checked and adjusted to prevent forward flow unless the product pressure in the pasteurized side of the regenerator is at least 6 9 kPa 1 psi greaater than the pressure in the raw product side of the regenerator In the case of product to water to product regenerators protected on the pasteurize or aseptic side the water side of the regenerator shall be considered to be the raw product for purposes of this test 275 276 PASTEURIZATION TESTING PROCEDURES Procedures a Wire test lamp in series with the signal from the pressure differentail switch to the flow diversion device b Calibrate the pressure switch and
26. Installation Requirements 1 Booster pumps may be installed between the balance tank and the raw regenerator and may operate only when ALL of the following conditions are met Y The booster pump is interwired with the timing pump and can only operate when the timing pump is running The booster pump is interwired with the flow diversion valve and can only operate when the valve is in forward flow The booster pump must be wired through an automatic pressure control device that will only permit the booster pump to operate when the pressure in the pasteurized side of the regenerator exceeds by at least 1 pound per square inch the pressure generated by the booster pump This pressure control device must be set and sealed at the required differential values by the regulatory agency Testing of the differential pressure controllers will be discussed later in the testing section of this manual 2 REGENERATOR PRESSURE CONTROLLERS a The differential pressure controller is the most commonly used booster pump controller Both capillary and electronically operated pressure differential controllers are available The mechanical capillary type controllers provide a visual indication of both the raw and pasteurized pressure within the regenerator while maintaining the correct pressure relationship The electronic controllers display the differential set point and a continuous reading of the system differential pressure 144 HTS
27. STUDIES CASE 9 HTST pasteurizer with CIP separator on the pasteurized side between regenerator 1 and 2 with a homogenizer located on the pasteurized side and a meter based variable frequency AC drive system In this particular system the booster pump is located between raw regenerator 1 and raw regenerator 2 Cream is precooled through raw regenerator 1 332 CASE STUDIES CASE 10 HHST pasteurizer with positive displacement timing pump a vacuum chamber flash chamber with direct steam infusion using milk water milk regenerative heating FDD at the end of the cooler section and a centrifugal pump between the balance tank and the raw regenerator 333 CASE STUDIES 334 335 COURSE CRITIQUE MILK PASTEURIZATION CONTROLS AND TESTS 302 DATE LOCATION Excellent Poor 1 What is you overall rating of thiscourse 6 5 4 3 2 1 2 How would you rate the facility 6 5 4 3 2 1 the most useful aspect of the _____________________________________________________________ 4 What suggestions can you offer for improving this course 5 Please give us your comments course handouts manuals 6 Would you recommend this course to others working in the milk sanitation field N explain BEST PART OF THE COURSE 1 WORST PART OF THE COURSE 337 DEFINITIONS AMPERAGE AMPS The amount of current flow through a conductor ATMOSPHERIC PR
28. See Balance Tank COOLING SECTION The section of a heat exchanger press in which one of several non toxic coolants flows in a counter current direction on the opposite side of a stainless steel plate of the pasteurized product DEFLECTOR PLATE A stainless steel plate in the regenerator section of the press designed to change the direction of flow DMO The latest edition of the Dry Milk Ordinance This Ordinance covers all Grade A milk drying and condensing plants DRT Digital Reference Thermometer This is usually referred to the electronic indicating thermometer which provides a readable L E D display provided by a signal from a dual element 8 wire resistive 1000 ohm type sensor element FLOW DIVERSION DEVICE Either a single stem one three way valve or dual stem device two three way valves connected by a common yoke designed to change the direction of product flow controlled by the recorder controller FDD Prevents the forward flow of raw milk FLOW CONTROLLER An instrument used in meter based systems which compares the flow signal from the flow transmitter to a set point and either controls the centrifugal pump speed or regulates a flow control valve downstream of the meter and centrifugal pump FC FLOW TRANSMITTER An instrument used in meter based systems which converts signals from the magnetic flow meter to a 4 20ma current FT FREQUENCY PEN A solenoid actuated recording pen located on the outer edg
29. Time of exposure varies c Time temperature is lethal to pathogens in vegetative state many 2 CANNING a Temperatures are above 212 F b Time of exposure varies Lethal to spores rod shaped botch cook 3 STERILIZATION a Temperatures are above 250 F b Time of exposure is short to minimize product damage c Implies commercial sterility where level of viable cells is a statistic Commercial sterility is defined as the time temperature relationship necessary for destruction and or inhibition of the organisms of public health significance as well as all significant spoilage organisms and is specific for each food type and formulation Thermal process is necessitated by the fact that plant and animal tissue and fluids are normally and naturally contaminated with microorganisms and or enzymes which may cause undesirable changes in the product during storage 26 non pathoge BACKGROUND AND HISTORY Pasteurization is a thermal process that kills part but not all of the vegetative microorganisms in the food and is consequently used for foods which are further processed or are stored under conditions which minimize growth In the case of milk pasteurization is used to kill pathogenic microorganisms Since some vegetative spoilage organisms and spores may survive this heat treatment it is necessary to keep pasteurized milk refrigerated in order to obtain the desired shelf life Therefore in additi
30. a magnetic meter timing system Dual stem valves which have both bodies mounted vertically must have sealed time delays The G amp H FDD including the newer vertically mounted G amp H because the connecting yoke is configured to be self draining is exempt from this time delay requirement 2 INSPECT TIME DELAY When the mode switch is moved from the PRODUCT or PROCESS position to the INSPECT position the valve must immediately assume the DIVERT position and all flow promoting devices must be immediately de energized After all flow promoting devices have completely stopped or have been effectively valved out of the system the flow diversion device may move to the FORWARD FLOW position for inspection or servicing Note A maximum of one second time delay is allowed during transition movement times of the flow diversion device Provided that a one second maximum off time delay is allowable to maintain the flow promoting device in the on position through the travel time of the valve s NCIMS 93 This removes the requirement for de energizing the flow promoters i e timing pumps homogenizers and valving out of separators during times required for the flow diversion device to move to the forward or divert flow position 109 3 CIP TIME DELAYS Condition 1 timing pump or other flow promoting devices not operating during the CIP operation Requirement Time delay for run down times of all flow promoters w
31. accommodate or delete items that are unique to a specific HTST system such as magnetic flow meter timing systems and flow diversion device time delays The vendor must provide a protocol in the user s manual so that the installer user and or Regulatory Official can demonstrate that the program performs as designed under actual production conditions 19 The logic diagrams for the flow diversion device and booster pump show programmed CIP operation as part of the computerized system Some plant operators may wish to use another computer for CIP operations so that CIP programs may be changed by plant personnel as needed When this is done the connections between the flow diversion device booster pump and plant computer must be provided with solenoid relays or similar devices on the outputs to the flow diversion device and booster pump to prevent them from being operated by the plant computer except when the mode switch of the flow diversion device is in the CIP position 20 The public health computer logic must also prevent illegal operation of flow promoting devices timing pump booster pump other product pumps when the mode switch is placed in the INSPECT position This will prohibit any forward flow of any sub legal product when the flow diversion device assumes the forward flow position following after the required time delay 364 CONSIDERATIONS FOR USE OF NON PUBLIC HEALTH COMPUTERS ON PAST EURIZER CONTROLS BOOSTER PUMP
32. be increased by degrees F 6 The FDA Dairy Inc vat pasteurizes their cheese milk at 173 F The operator Mr I M Messed Up must always check to make sure that the air space temperature reads at least during the entire holding time 7 What is the purpose of VALVE close coupling 8 You are the night manager of a large milk processing plant The vat pasteurizer 53 VAT PASTEURIZATION operator notifies of the following CONDITION YOUR SOLUTION a He forgot to add dry sugar to the mix prior to pasteurization however did add the sugar at only five minutes into the beginning of the 30 minute time and then added 25 minutes to the time after adding the sugar The mix was packaged last night and is ready for shipment b The air space thermometer was damaged and the mercury slightly separated however since the milk was pasteurized at 170 degrees he had decided to package the product and was delivered this morning to the store c The boiler lost steam pressure during pasteurization but since the temperature never got below 145 the cream was packaged and in the plant cooler anyway d Pasteurized skim was put in a processing vat super heated culture was added and then pumped to the vats for cottage cheese processing e The operator discovered that they had used the last vat recorder chart the previous day HTST charts were used on the vat recorder since the charts included the normal pasteurization tem
33. carbon core equivalent i ALTERNATIVE CHECK VALVE CONDENSATE LEG d Desuperheater or sufficient e length of piping to desuperheat steam shall be incorporated between the pressure regulating reducing valve and the steam purifier gt Sanitary tubing and fittings PROCESSING shall be used between the point 4 2 EQUIPMENT r indicated and the processing mu equipment CONDENSATE TRAP Note Additional valves strainers traps gauges and piping may be used for control and convenience in operation The location of the steam throttling valve is not re stricted to the positions indicated on the drawing The position of the steam purifier and Adams carbon core filter may be reversed if desired Figure 50 Culinary Steam Piping Assembly for Direct Addition to Milk 163 6 When a water feed line is connected to a direct water vapor vacuum condenser supplementary means shall be provided to preclude the back up and overflow of water and or condensate from the vacuum chamber into the product vacuum chamber in the event of condensate pump failure or power failure Such means Shall include the use of a An automatic shut off valve installed in the water feed line coupled with b A high level sensing device installed in the condenser which would shut off the condensing water if the water or the condensate rises above a predetermined level in the condenser This valve may b
34. difference This recorder controller requires a separate hot water temperature controller to automatically control the temperature of the steam heated water used in the heating section of the press The hot water controller automatically controls the steam valve which increases or decreases the amount of steam allowed into the heating medium depending on operator setting 81 Illustrated below is the basic design function of a recorder controller LOWER DIVERSION POINT ADJUSTING SCREW BAFFLE ARM SUB ASSEMBLY OVERTHROW LINK PIVOT OVERTHROW LINK m X UPPER DIVERSION POINT e ADJUSTING SCREW STOP PLATE ELLA BAFFLE PIVOT J FLEXIBLE STRIP SOLENOID BOURDON ZERO SCREW SPRING SAE S DIVERSION POINTER BAFFLE NOZZLE MICROSWITCH 20 PSI AIR SUPPLY FINAL MILK TEMPERATURE BULB PNEUMATIC COMPONENTS OF DUAL DIVERSION RECORDER CONTROLLER Figure 15 Taylor STLR 82 Basic HTST Pasteurization The Partlow Recorder Controller This recorder controller combines both the flow diversion device recorder controller and the hot water temperature controller The right side mechanism which uses a liquid filled sensing bulb to activate a plunger mechanical switching system to control the recorder pen and the flow diversion device The sensing bulb is located at the outlet of the holding tube The Partlow STLR Model J755A showing door open with temp recording pen hot wate
35. have also been bypassed b Immerse the sensing element from the flow diversion device in the bath which is above the cut in temperature The test lamp should remain unlighted i e diverted flow Remove this sensing element from the bath c Immerse the sensing element from the vacuum chamber in the bath The test lamp should remain unlighted i e diverted flow Remove the sensing element from the bath 308 PASTEURIZATION TESTING PROCEDURES d Immerse two sensing elements from the vacuum chamber and flow diversion device in the bath The test lamp should remain unlighted i e diverted flow Leave the two sensing elements in the bath e Immerse the sensing element from the holding tube in the bath The test lamp should light up i e forward flow after a minimum time delay of 1 second for continuous flow pasteurizatin systems For aseptic processing systems no delay is required if the filed process includes a documented sterilization period f Remove one sensing element the flow diversion device from the bath The test lamp should remain lighted i e forward flow g Remove another sensing element the vacuum changer from the bath The test lamp should remain lighted i e forward flow h Remove the last sensing element the holding tube from the bath The test lamp should go out i e diverted flow immediately l Re immerse the sensing element holding tube in the bath The test lamp should remain un
36. holding tube lengths have been calculated as twice the length to compensate for laminar flow in the following table HOLDING TUBE LENGTH INCHES FOR HHST INDIRECT HEATING PASTEURIZERS ASSUMED PUMPING RATE 1 GAL SEC HOLDING TUBING SIZE INCHES TIME SECONDS Note Minimum processing temperatures must coincide with required holding times The conditions in these systems which require product diversion are 1 Improper temperature and 2 Improper pressures within the regenerator 3 Excessive flow rate if equipped with a meter based timing system REGULATORY CONTROLS INDIRECT HEATING 1 MILK TO MILK REGENERATORS a One controller is located at the end of the cooling section and b the STLR located at the end of the holding tube and C a differential pressure controller is installed when a booster 194 just pump HHST UP AND UHT SYSTEMS Note In the above instance the differential pressure controller is set to monitor the highest pressure in the raw product side and the lowest pressure of the pasteurized side in the regenerator as in conventional HTST systems d In these HHST systems since all product surfaces are exposed to liquid at pasteurization temperatures 191 F or above following product diversion the requirements for a vacuum breaker at the end of the pasteurized regenerator and the height requirement of the constant level tank may be eliminated 2 Product to Water to Product Regene
37. necessary in addition to the vacuum breaker located after the pasteurized regenerator If the cream from a pasteurized side separator is returned to be precooled in a regenerator using raw milk on the opposite side of the plates then an additional vacuum breaker is required between the beginning of the cream line and the entrance to this regenerator 139 PASTEURIZED mr OUT I lt 1 DRAIN VACUUM PAST BREAKER BACK PRESSURE VALVE Na AND CONTROLLER TYPE SEPARATOR SKIM BACK FLOW D N VACUUM PRESSURE Op DIVERSION BREAKER VALVE DEVICE r4 J SPADA ESTRICTOR STLR CHR T i BY PASS VALVE SEPARATOR 1 t du FEED VALVEU9 gt E J E LEAK DETECT LINE HOLDING AIR BLOW n DIVERT LINE an TUBE 6 CUULER SPLIT REGENERATOR HEATER SIGHT 3 RECYCLE LINE ____ GLASS S um 2 2 NI CONSTANT RAW PRODUCT IN LEVEL TANK REGENERATOR 6 BY PASS VALVE 6 BOOSTER PUMP i QJ STUFFING PUMP Figure 37 HTST with Booster Pump Stuffer and Pasteurized Separator 140 HTST Auxiliary Equipment AUXILIARY RAW PRODUCT PUMPS CENTRIFUGAL SANITARY PUMPS Centrifugal sanitary pumps are usually direct motor driven and their pumping capacity varies with 1 motor and impeller size and 2 amount of back or downstream pressure The pump will not be damaged by closing off of t
38. not constitute endorsement by the U S Department of Heath and Human Services Public Health Service Food and Drug Administration K K K K K K K K K KK KKK KKK K 345 346 347 APPENDIX HTST PASTEURIZATION EQUIPMENT TESTS CRITERIA METHOD PROCEDURE RESULTS STLR Time Compare at 30 Min STLR Time Accuracy Actual IND TEMP At Past Temp using Accuracy IND 5 Cert Therm STLR Temp 1 F 5 Min Stabilization Past 5 Min Boil 5 Min 9 Stabilization 5 Min in 5 min 9 2 min STLR v s Ind Daily Compare at past temp 1 STLR not higher using milk Cut In Cut Out Ind Therm reading when valve changes FF DF 1 F 30 sec Ind Therm 4 sec 12 F span Response H20 bath 173 F Start 154 stop 166 STLR Therm Resp 5 sec start 12 F below cut in stop system cut in bath 7 above cut in 349 4 Regenerator Pressure Controls 5 Booster pump wiring Holding Time Flow Diversion Device FDD Proper Assembly FDA STB 4 gt 1 psi on Past side set Taylor DPC 2 psi 5 interwired w FDD b w PDC EE w timing pump Salt test 6X w i 5 sec DUAL STEM l leakage past seat 2 operation of valve stem 4 device assembly 5 manual diversion 6 response time 7 interlock with flow promoters INSPECT and CIP time delays 8 10 min CIP time delay if applies SINGLE STEM 1 2 3 hex nut lt turn stops TP 5 6
39. of 125 F 160 F and subsequently bulk shipped the product must then be classified as heat treated cream and must meet the current labeling temperature and sampling requirements Separators located between two milk to milk regenerators on the raw side must meet all requirements of a booster pump for example they must be interwired with the flow diversion device the timing pump and a pressure differential controller device This also applies to the stuffer pump if located in the same position The reason for this is obvious During divert or shutdown the separator and or stuffer pump could continue to pump milk into the raw side of the regenerator causing possible contamination of raw milk into the pasteurized milk side Also should the timing pump suddenly lose power the separator assembly could continue to act as the timing device in the system 137 FLOW REGENERATOR HEATER aD BACK PRESSURE 7 VACUUM DIVERSIDN VALVE A BREAKER E VICE i STLR CHR 1 PASTEURIZED PRODUCT ZED LEAK DETECT LINE 1 PASSO Or 6 RAV HN DRAIN STUFFING BOOSTER PUMP Freep vtm SEPARATOR BY PASS VALVE e CREAM RETURN VALVE CIP TYPE SEPARATDR CREAM DUT Figure 36 HTST with Booster Pump Stuffing Pump Raw Separation HTST Auxiliary Equipment 4 Separators located on the pasteurized side of the system must be automatically valv
40. on the bottom through which the milk exits the tubes De aerated culinary steam enters the chamber at the top Fitted on the chamber top is a pressure relief valve pop off valve which is one of the flow controlling forces of the system Inside chamber showing milk regulating product pressure throughout the system entrance port to the flash chamber Steam and pressure is thus the primary flow promoting element in this system The pressure release valve is usually set at 60 psi to 75 psi This pressure release valve must be sealed by the regulatory agency The bottom portion of the sterilizer chamber is cone shaped and the cone is normally water jacketed so the chamber skin does not exceed 250 F Product in the chamber is usually heated above 280 F The milk undergoes heat penetration within the chamber by maintaining and controlling the density and thickness of the falling film The film of milk is thin enough to maintain effective heat penetration Tempered water jacketing the bottom of the chamber helps to prevent burn on 219 Product leaving the sterilizer chamber then passes through a holding tube calculated holding time and enters a second vacuum vessel known as the FLASH CHAMBER through a sealed ORIFICE This orifice is properly sized to maintain a back pressure which is another one of the flow rate controlling devices in the system As the product enters into the flash chamber through the sealed properly sized
41. pressure switch setting 270 PASTEURIZATION TESTING PROCEDURES Method The differential pressure switch is checked and adjusted to prevent operation of the booster pump or prevent forward flow unless the product pressure in the pasteurized or aseptic side of the regenerator is at least 6 9 kPa 1 psi greater than the pressure in the raw side of the regenerator 9 2 1 CALIBRATION OF DIFFERENTIAL PRESSURE CONTROLLER PROBES Procedures a Loosen the process connection at both pressure sensors and wait for any liquid to drain through the loose connections Note At this point do not remove sensors from their location on the press Both pointers should be within 3 5 kPa 0 5 psi of 0 kPa 0 psig If not adjust pointer s to read 0 kPa 0 pounds psig b After identifying both sensors raw and pasteurized remove them from the processor and mount them in a tee either at the discharge of the booster pump or connected to the pneumatic testing device Note in writing if necessary the separation between the two pointers The change in elevations of the sensors may have caused some change in the zero readings Turn on the booster pump switch and depress the test push button to operate the booster pump Note If the pneumatic testing device is used in lieu of the booster pump adjust air pressure to the normal operating pressure of the booster pump Note that the pointer or digital display reading separation is within
42. probes using test 9 2 1 1 Adjust the pressure the pressure switch sensors to their normal operating pressures with the pasteurized or aseptic pressure at least 14 kPa 2 psi higher than the raw product pressure 2 The test lamp should be lit If the test light is not lit increase the pasteurized or aseptic pressure or lower the raw product pressure until the test light is lit 3 Gradually lower the pasteurized or aseptic side or raise the raw product pressure until the test light turns off 4 The test light should turn off when the pasteurized or aseptic pressure is 14 kPa 2 psi or more haigher that the raw product pressure 5 Note the differential pressure at the point the light turns off 6 Gradually raise the pasteurized or aseptic pressure or lower the raw product pressure until the test light turns on 7 The test light should not turn on until the pasteurized or aseptic pressure is grater than 14 kPa 2 psi higher than the raw product pressure Note the differential pressure at the point the light turns off Note This test may be completed using a pneumatic testing device capable of producting differential pressures on the probes This device should be capable of being operated in a manner so as to duplicate the conditions described above d Seal the instrument and record the test results for the office record 277 9 3 ADDITIONAL HTST TESTS FOR BOOSTER PUMPS Application To all booster
43. problems with cross connections and post pasteurization contamination 1990 Outbreak of Staph enterotoxin associated with whipped butter in a large hotel in Reno NV Suspect temperature abuse at the processing plant Testing at the source of butter manufacturer showed negative for staph organisms 1992 E Coli 0157 outbreak reported transmitted by ingestion of 17 BACKGROUND AND HISTORY unpasteurized milk 1993 Type A Botulism toxin caused at least one death in Georgia Problem associated with institutional packaged 10 can cheese spread in small convenience type store 1994 Salmonellosis enteritidis outbreak THOUSANDS of cases reported from consuming contaminated ice cream Plant located in Midwestern state shipping to 48 states Firm received mix and did not re pasteurize prior to freezing and packaging Follow up shows mix was hauled in a tanker which was just prior used to haul raw liquid eggs Two consumer samples were presumptive positive Product was immediately recalled from the market This outbreak should send a message to the ill frozen dessert industry that all mix SHALL BE PASTEURIZED in the plant of packaging and the unnecessary handling of pasteurized milk products must not be condoned 1995 Yersiniosis enterocolitica outbreak reported in New England Epidemiological studies placed suspect on contamination of pasteurized milk from operation of a small swine operation on the premises of the p
44. readily identifiable and are so designed that stoppage of the divert line cannot occur g The leak detect line shall be designed to discharge all leakage to the floor or back to the constant level tank This leak detect line must not be connected to the divert line and shall not have any restrictions A sight glass must be installed in the leak detect line if connected to the constant level tank This sight glass must be of the full see through clear material providing vision on both sides of the cross fitting design and be installed in the vertical line The only exception to this requirement is the provision for a transparent tube assembly which is self draining may be installed horizontally 108 Tite Relays 1 YOKE FLUSH TIME DELAY At least one second between actuation of the divert valve and the leak detect valve when moving from the diverted flow to the forward flow position The purpose of this is to flush the connecting line of any possible raw milk remaining in this connecting yoke On systems having identifiable restrictors in the divert line the maximum time delay divert valve to leak detect valve flush time must never exceed 5 seconds This prevents sub legal 15 seconds milk which may have been traveling down the UNRESTRICTED leak detect line milk from entering into the pasteurized side of the system at the instant of forward flow This maximum 5 second flush delay does not apply to systems using
45. recycle lines which return to the constant level tank must break to atmosphere at least two pipe diameters above the overflow level 3 The overflow level of the constant level tank must be lower than the bottom of the inlet of the raw regenerator 4 if by pass valves are used they must be pinned to prevent improper positioning OTHER COMBINATIONS OR MODIFICATIONS WHICH ARE INSTALLED AND OPERATED IN ACCORDANCE WITH THE DETAILED PROVISIONS OF THESE PRACTICES MAY BE UTILIZED 134 HTST Auxiliary Equipment r 1 1 PASTEURIZED PRODUCT 1 2 DUT E I LEAK DETECT LINE 44 T COOLER REGENERATOR Y HEATER HOLDING TUBE 2 JV EVM SIGHT ae GLASS 0 a5 si FLOW VERSION VACUUM pve LOWS T B By pass OPTIONAL 4 RECYCLE LINE TIMING PUMP as RECTEVE X I o RECYCLE LINE en Y RAV DRAIN EE Figure 34 Homo used as Timing Pump when Homogenization is desired 135 Separators 1 Definition Separation of whole milk is used for the partial or complete removal of milk fat particles cream from the product This process is accomplished by exposing the whole milk to a centrifugal force through a series of high speed rotating discs or plates 2 Application Whole milk enters the separator it is accelerated to high speeds The plates within larger separators rotat
46. reflect this volume increase therefore it is not needed to be included in field calculations This 203 surplus water is subsequentially evaporated as the pasteurized product is cooled in the vacuum chamber Note Laminar flow adjustments for Aseptic System shelf stable holding tube lengths may not always be required by the Process Authority on milk processed in those systems having filed processes and meeting the Low Acid Canned Food LACF CFR Regulations TABLE 1 HOLDING TUBE LENGTHS FOR STEAM ECTION PASTEURIZATION ASSUMED PUMPING RATE 1 GAL SEC HOLDING TUBING SIZE iNcHES Note These lengths assume fully developed laminar flow and temperature increase of 120 F by steam injection The table used for direct steam injection contains holding time calculations that have been adjusted for longer holding tube length s which compensates for the increased volume of product because of the injected steam prior to the holding tube This increased volume could be as much as 13 204 HHST UP AND UHT SYSTEMS HOW TO USE THIS TABLE This table may be used to calculate the required holding tube length for any flow rate This can be done by determining the time required for the pasteurizer operating on water at operating conditions to fill a vessel of known volume This data is them converted by division to obtain the flow rate in gallons per second and multiplying this value by the applicable number in Table 1 The res
47. shall also be protected against heat loss with insulation that isimperviousto water if the temperature sensor islocated at the beginning of the holding tube Reseal as necessary Alternate procedure For pasteurizers of large capacity the method of measuring flow rate at the discharge of the pasteurizer is inconvenient and the following alternate test procedure may be used a Remove the divert line from the raw product supply tank and turn off the product pump feeding the raw product supply tank b Suspend a sanitary dip stick in the raw product supply tank and operate the pasteurizer at maximum capacity c Record the time required for the water level to move between two graduations on the dip stick Calculate the volume of water from the dimensions of the raw product supply tank and the drop in water level Determine flow rate as follows Divide the volume of water in gallons removed from the raw product supply tank by the time in seconds required to remove it Then use Table 14 to calculate the required holding tube length Corrective Action If the length of the holding tube is shorter than the calculated length reseal the metering pump at a slower maximum speed or lengthen the holding tube or both and repeat the procedure 302 PASTEURIZATION TESTING PROCEDURES 11 5 HOLDING TIME STEAM INFUSERS WITH STEAM POP OFF VALVE AND VACUUM CHAMBER ORIFICE USED IN PLACE OF A TIMING PUMP Application To all HHST pas
48. temperature by injecting steam into the milk stream held in a holding tube and then pre cooled in a vacuum chamber whereby added water in the form of vapor is removed The milk is then cooled to the desired storage temperature in a heat exchanger As in indirect heating systems the flow diversion device is also located at the end of the system as the product exits the cooler a ISOLATION OF THE STEAM INJ ECTOR CHAMBER Steam injection is an inherently unstable process When steam is injected into a fluid complete condensation of the steam must be assured within the injector This is accomplished by the properly designing and in some cases adjusting the steam injector itself Lack of complete condensation within the injection chamber may result in product temperature variations within the holding tube This could lead to some milk particles being processed below the required pasteurization temperature One method of isolation is to insert supplementary orifices on the product inlet and the heated product outlet of each injector Most of the available manufactured injectors have a built in orifice on the steam port therefore a supplementary orifice is usually not necessary in the steam line Refer to manufacturer specifications for sizing and spacing parameters The injector must be interwired to permit the flow diversion device from assuming the forward flow position only when the differential pressure drop across the injector is at least 70
49. to Level 2 CH Lo chart low Set process value at 120 F 3 Move display prompt to Level 2 CH H1 chart high Set process value at 220 F 4 Move display prompt to Level 2 deG C Set process value as no Fahrenheit temperature scale selected Note These process values are for chart No 500P1225 35 with low and high limits of 120 F and 220 F If a different chart is used the low and high limits of that chart must be used If a different chart is used it must meet the specifications of Appendix H 5 Move the display prompt to Level 2 FlLt Set process value as no chart damping filter disabled 6 Move display prompt to Level 2CHrt SPed Set process value at 12 chart rotation period in hours 7 Move display prompt to Level 3 ALr H Set process value at 220 F or the maximum temperature on the chart high alarm set point 8 Move display to Level 3 ALr IH Set process value at least 0 5 F higher than the minimum pasteurization temperature low alarm set point 9 Move display prompt to Level A HYS Set process value at 1 F alarm hysteresis which determines the difference between cut in temperature and cut out temperature 10 Move display prompt to Level 3 ACK Set process value as no deletes acknowledge routing to level 1 11 Move display prompt to Level 4 CAL H calibrate all pens to the outer edge of the chard Observe that the recording pen and event pen drop to the outer temperature line on the chart If t
50. to make adjustments to any settings other than pen accuracy the chart plate seal must be removed and the internal sedurity shunt must be moved from the run upper position to the program lower position This shunt is located on the STLR interconnect board in ht e lower left hand corner of the instrument It is labeled J 01 and is positioned 1 inch below the upper right corner of the board For program mode position the shunt on the lower two pins For run mode move it up one position The unit will only operate in run mode Finally during initial installatin make a note of the labels on the EEPROM chips labeled U7 and U8 inside the unit before applying the health authority seal Test 2 and 4 Temperature Accuracy Thisisthe only health code related function that can be adjusted the run mode It allowsthe operator or health authority to adjust the pen to agree with a verified indicating thermometer After testing the accuracy using the PMO procedure adjust the recording pen to agree with the verified indicating thermometer as follows l Pressthe scroll key on the keypad just to the right of the ESC key The display will read SELECT FUNCTION SETUP 2 Press the DOWN arrow key Use the scroll key until STLR flashes on the display 3 Pressthe unlabeled button under the flashing STLR display The display will read STLR INP DISPLAY OPT 4 Press the Scroll Key until the display reads STLR INP CORRECTION
51. use of trade names or equipment photographs is for training and educational purposes only and does not constitute endorsement by the Food and Drug Administration Acknowledgments The development preparation and publication of this course manual is the responsibility of the State Training Branch Division of Human Resources Development Food and Drug Administration The updated schematics of HTST systems were taken from the 3 A Accepted Practices for the Sanitary Construction Installation Testing and Operation of High Temperature Short Time and Higher Heat Shorter Time Pasteurizer Systems Revised Number 603 06 The National Conference on Interstate Milk Shipments has resolved in their Conference agreements to fully support the training efforts of the FDA The requirements and legal aspects found within this manual were taken from previous editions and printing of this manual and the current edition of the Grade A Pasteurized Milk Ordinance and acknowledgment is given to all the previous contributors of that document This edition of the training manual was compiled prepared and edited by CAPT Richard D Eubanks USPHS Training Officer FDA ORA DHRD State Training Branch with major rewriting of the HHST UHT Chapter and revisions in other portions of the testing section Technical and word processing assistance was provided by CDR Artis M Davis USPHS Regional Milk Specialist Southwest Region Appreciation is also given to the Regional
52. 0 F or more and be maintained thereat until the time of injection 7 If computers or programmable controllers are used to provide any of these required functions they shall meet the applicable portion of Appendix H V 8 Appropriate test procedures shall be provided to evaluate the required inter wiring and function 125 Chapter Auxiliary Equipment LLLLELLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL Note The use of trade names or equipment photographs is for training and educational purposes only and does not constitute endorsement by the U S Department of Heath and Human Services Public Health Service Food and Drug Administration ok ok of ok of of of ok ok ok of of KK ok of ok KK K ok ok ok ok K ok ok ok ok ok ok 126 HTST Auxiliary Equipment DESIGN INSTALLATION AND OPERATION OF HTST PASTEURIZATION AUXILIARY EQUIPMENT PURPOSE To describe and understand the function operation and requirements for installation of auxiliary equipment within a HTST pasteurization system ECTIVES Following completion of this instructional unit the participant will be able to Describe the operation and function of each of the basic types of auxiliary equipment when installed within the HTST pasteurization system 2 Describe the requirements and criteria for installation of auxiliary equipment within the HTST pasteurization system Explain the public health reasons f
53. 1 simple inexpensive pneumatic testing device may be made from a discarded 50 millimeter 2 inch 7BX sanitary tee with AIR GAUGE OR REDUCER TEE PRESSURE SWITCH OR SENSING ELEMENT SENSING ELEMENT OF CORRECT TYPE DRILLED AND TAPPED TO ACCEPT PIPE 0 100 PSIG GAUGE HX ACCURACY VENT mil PRESSURE REGULATOR AIR SUPPLY 70 PSIG PNEUMATIC TESTING DEVICE two additional 13H nuts one of which is provided with a 16A cap drilled and tapped for a 13 millimeters galvanized iron nipple for the air connection 267 2 A hose connection is made to a compressed air source in the plant by means of a snap on fitting The air pressure can be controlled by an inexpensive pressure reducing valve range 0 60 psig followed by a 13 millimeters inch globe type bleeder valve connected into the side outlet of a 13 millimeters 72 inch tee installed between the pressure reducing valve and the testing device 3 The pressure switch to be tested is disconnected from the pasteurizer and connected to another of the outlets of the sanitary tee and the pressure gauge is connected to the third outlet of the sanitary tee 4 By careful manipulation of the air pressure reducing valve and the air bleeder valve the air pressure in the testing device may be regulated slowly and precisely In operating the device care should be taken to avoid exposing the pressure switch and the sanitary pressure ga
54. 286 PASTEURIZATION TESTING PROCEDURES j Repeat steps d through I for testing time on water in diverted flow With the pump at the same speed and equipment adj usted as a above time the filling of a 38 liter 10 gallon can with a measured weight of water using the discharge outlet with the same head pressure as in normal operation Average the time of several trials Since flow rates of large capacity units make it very difficult to check by filling a 38 liter 10 gallon can it is suggested that a calibrated tank of considerable size or other acceptable methods be used For all gear type timing pumps and homogenizer timing pumps with measured time of less than 120 of the legal holding time repeat procedure k using milk m Compute the holding time for milk from the following formula by weight using the average specific gravity Compute separately for forward flow and diverted flow Tmz1 032xTw Wm Ww which 1 032 specific gravity for milk TW average holding time for water Tm Adjusted holding time for milk time required to deliver a measured weight of milk Ww time required to deliver an equal weight of water n Record results for office record The holding time for milk may also be computed from the following formula by volume Compute separately for forward flow and diverted flow Tm T Mv Ww in which TmzAdjusted holding time for milk T ave
55. 3 RAW MILK C HEATED MILK C PASTEURIZED MILK L JDIVERTED UNDERHEATED MILK HEATING WATER STEAM cm COOLANT 2 gt 37 S 3 WAY VALVE 1 VACUUM BREAKER DIVERSION LINE SWEET WATER OUT CONSTANT cO v HOT WATER Ns Ne TEMPERATURE m CONTROLLER el Re L RAW MILK sucxep 2 4f FROM CONSTANT 49 LEVEL TANK AND SY ATHROUGH REGENERATOR RECORDER CONTROLLER STEAM IN CONTROL PANEL A WA TER ETERS Ey VALVE SN 5 lt lt lt gt FLOW DIVERSION 97A T WATER Dy NG UNIT a NN HIGH TEMPERATURE SHORT TIME PASTEURIZER HOT W CIRCULATI 10 Chapter BACKGROUND AND HISTORY History Department Caw Collece MILK PASTEURIZATION THEN AND NOW Although Louis Pasteur is the one name most often referenced in discussions the inception of what we now know as pasteurization actually the concern for methods to preserve the safety of milk began long before Pasteur s first experiments of heating wine to preserve its freshness As early as the 1500 s Austrian officials implicated milk in an epidemic which led to much thought concerning safety issues of milk consumption However it was not until 1824 that William Dewees recommended the application of heat to mi
56. 6 9 kPa 1psi of that observed before pressure was applied If not the instrument requires adjustment or repair 271 c Record the test results for the office record Reseal the instrument controller and any seals broken on electronic pressure sensor devices FOR PNEUMATIC OPERATED PRESSURE DIFFERENTIAL CONTROLLERS 1 Quickly exhaust the air from the pneumatic tube while closely observing the pressure indicators as they drop to their static position or 0 If the comparison exceeds scale unit during the drop the unit in need of further evaluation Probable causes may be a Unequal sized capillaries raw v s pasteurized b Unequal lengths of capillaries c Damaged capillary s crimped etc Note Both raw and pasteurized capillary tubes should be replaced at the same time Also both should be the same length and internal diameter 2 Note that both of the pointers separation is within 07 kPa 1 psi of that observed before pressure was applied If not the instrument sensors or capillary are malfunctioning and require immediate maintenance c Device specific testing procedures 272 PASTEURIZATION TESTING PROCEDURES Ae pers 1 2 TESTING THE DIFFERENTIAL CONTROLLER WITH A CDT DEVICE DEVICE ACCURACY TEST Attach the tubing from OUTLET A to the PASTEURIZED SENSOR Attach the tubing from OUTLET B to the RAW SENSOR Attach an supply air hose to the CDT Place the selector switch in the
57. 73 F 154 F 166 F 175 F 182 F 163 F 175 F Corrective Action If the response time should exceed 4 seconds the ther mometer should be replaced or returned for repair 264 PASTEURIZATION TESTING PROCEDURES TEST 8 RECORDER CONTROLLER THERMOMETRIC RESPONSE Reference Item 16p E Application To all HTST recorder controllers used in connection with continuous flow pasteurizers except those in which the flow diversion device is located at the end of the cooler section ie HHST and Aseptic Processing Systems Frequency Upon installation and at least once each 3 months thereafter Criteria Five seconds under specified conditions Apparatus Previously tested indicating thermometer on pasteurizers stopwatch water bath agitator and heat supply Method Measure the time interval between the instant when the recording thermometer reads 7 C 12 F below the cut in temperature and the moment of cut in by the controller This measurement is made when the sensing element is immersed in rapidly agitated water bath maintained at exactly 4 C 7 F above the cut in temperature Procedure 1 Check and if necessary adjust the pen arm setting of the recording ther mometer in the proper reference to agree with the indicating thermometer reading at pasteurization temperature 2 Determine the cut in temperature of controller Test 10 p 224 either while in normal operation or by using a water bath 3 Remove se
58. 7K and 447K Model A represents pasteurized regenerator pressure For operational scale calibration purposes pressure differentials on these instruments are usually set at a minimum of pounds 9 Which statement is most accurate about differential pressure controllers a Controls the pressures within the milk to milk regenerator b Operates only in forward flow c Is interwired with the timing pump d Shuts off the booster pump when the pre set differential is not met 10 What is the purpose of a Ratio Controller 11 What boiler additives may be used in milk processes using direct steam contact with milk product 13 Explain why raw milk separators must be installed prior to the timing 167 14 Describe installation and operation of differential pressure controller sensors OPERATING TIMING BOOSTER HOMO STUFFER SEPARATOR VACUUM CONDITION PUMP PUMP GENIZER PUMP a anm RI POWER FAILURE T PROPERLY SEATED Comments Figure 51 Operation Condition Exercise 168 169 Chapter V 170 MAGNETIC FLOW METERS PURPOSE To describe the purpose of using a magnetic flow meter in a HTST pasteurization system including function operation and installation requirements ECTIVES To understand the principles function and purpose of using a magnetic flow meter in an HTST pasteurization system To become familiar with the public health controls and installation req
59. ACK x PRESSURE I x VALVE pol 3 VACUUM PRESSURE OPTIONAL Let BREAKER VALVE AND i RESTRICTOR FLow CONTROLLER TT TE aX V os 7 cod 2 SEPARATOR VES Iam Fi 4 iei i we i ny I 4 PASTEURIZED CREAM our RAV Propucr DRAIN CONSTANT HOMOGENIZER LEVEL TANK 2 BOOSTER PuMe STUFFING Pume Fig 43 HTST with booster pump homo timing pump and separator between two pasteurized regenerators with cream cooler 1 This line shall be horizontal at least 12 inches above any raw piping in HTST system 2 All divert leak detection and recycle lines which return to the constant level tank must break to atmosphere at least two pipe diameters above the overflow level 3 The overflow level of the constant level tank must be lower than the bottom of the inlet of the raw regenerator 4 regenerator by pass valves must be installed to be drainable and must prevent dead ends or be drilled A drilled check valve may be used between inlets of booster pump and timing pump Air operated valves must be normally open automatically operated and controlled to open if timing pump stops 5 when separator or clarifier is an integral part of the HTST or HHST system and is located upstream of the timing pump or downstream of the flow diversion device it shall be automatically valved out of the system with fail safe valv
60. CIP and improper flow diversion device seating 3 The location of all public health controls and the location of regulatory seals required to safeguard the system The major public health consideration in using auxiliary equipment is to determine effects on time temperature pressure relationships within the system Specifically this equipment must be installed so that 1 It will not reduce the minimum required holding time below the requirements 2 It will not interfere with the detection of or stoppage of forward flow of milk which is below the minimum pasteurization temperature 3 It will not disturb the maintenance of proper pressure relationships within the regenerator section of the system 322 CASE STUDIES EQUIPMENT COMPONENT LIST recorder controller flow diversion device holding tube divert line regenerator balance tank recirculation line recycle line vacuum breaker separator stuffing pump back pressure valve check valve centrifugal pump regulatory seal booster pump cooler section heater section homogenizer leak detect line timing pump by pass line pressure differential controller indicating thermometer by pass valve positive shut off valve magnetic flow meter pressure sensor flow recorder controller sight glass 323 CASE STUDIES CASE 1 a HTST pasteurizer with a homogenizer of larger capacity than the timing pump and booster pump b Cream pasteurizer with conv
61. CULINARY STEAM VALVE POSITIVE SHUT OFF VALVE SUPPLY mien SeA 34 didi gt BREAKER FLOW DIVERSION DEVICE 8 i VACUUM BREAKER AUTOMATIC gs L 3 STEAM 1 STLR VALVE i PASTEURIZED PRODUCT LEAK DETECT LINE ES DUT e her 1 1 1 au f 4 VACUUM 1 L BP San 1 BREAKER i COOLER REGENERATOR HEATER i M Se e 4 HOLDING TUBE I t p i SIGHT GLASS O P RECYCLE LINE UA On DRAIN Ray PRODUC IN TIMING PUMP Figure 49 HTST with vacuum system downstream from flow diversion device and direct addition of steam 159 IV FLAVOR CONTROL EQUIPMENT A General Information Flavor control equipment which can include vacuum and vacuum steam systems may be installed in HTST pasteurization systems if ALL the following conditions are met The equipment does not 1 Interfere with the operation of the flow diversion device 2 Adversely affect the proper pressure relationships in the regenerator section of the press 3 Reduce the holding time below the legal minimum 4 Contaminate the product with toxic or other deleterious material from the steam 5 Add water to the finished product C Requirements 1 When vacuum equipment is located downstream from the flow diversion device an effective means of preventing negative pressure between the forward flow port of the flow diversion device and the inl
62. DIRECT CONTROL VER PUMP PUMP AME Tb REB LIGHT CONTROLLER ME EXHAGSTEB SOLEWDID WO AIR SUPPLY SPRING TENSION KEEPS AL E PLUNGER AGANST FORWARD FLOW SEAT E CUNRENT TO FRERUENCT REB LIGHT Figure 27 STLR and FDD Function Divert Flow 119 FORWARD FLOW FREQ PEN ARM RED LIGHT TEMPERATURE A AIR SUPPLY SENSOR RECORDER CONTROLLER 1 TEMPERATURE BR ABOVE CUT IN SETTING 2 COM EXPANSION PERMITS BAFFLE TO CLOSE AIR 3 AIR RACK FRESSIME DRIVES MICRDSWITCH CONTACT INTE CLOSED POSITION PROVIDING CORRENT TO FDY SULEMOID ANB TIMING 4 FREQUENCY PEN EWERGIZED 5 GREEM LIGHT DW BAFFLE ACTIVATING DIAPHRAGM D ou poet ERE ERIE ELE d aa EE a aal 2 aLGGROOVE H MICRO Core S ui n d CE PRIN ES cum AIR INLET S af coos oe FLOW DIVERSION DEVICE 1 F Y SOLEMOID ENERGIZED BY RECINDEER CONTROLLER MICROSWITCH 2 MR SEPPLY PASSES OVEN DIAPHRAGM DEPRESSING MARS RING 3 MICROSWITCH ROLLER RIES ABOVE QROOYE 4 MICHOSWITCH CONTACT NO PROVIDES CURRENT TO FRERMENCY ARM AMD GREEN LIGHT Figure 28 STLR and FDD Function Forward Flow 120 Basic HTST Pasteurization CHAPTER REVIEW Fill in the blanks 1 H T 5 T T L R R T D D R 2
63. E PRESSURE DIFFERENTIAL CONTROLLER WITH THE BOOSTER PUMP Method Determine if the booster pump stops when the pressure differential is not properly maintained in the regenerator Procedure a Connect the pasteurized pressure sensor to a testing tee with the other end of the tee capped Caution If there is water in the HTST system ensure that the recorder controller probe and the pasteurized sensor ports are capped before the metering pump is turned on b Turn the metering pump and the booster pump c Place the recorder controller probe in hot water which is above the cut in temperature d Apply and adjust air supply to the tee to provide an adequate pressure differential to start the booster pump e Decrease the air supply to the testing tee until the pressure is less than 14 kPa 2psi of the pressure on the raw milk pressure sensor The booster pump should have stopped Ensure that the flow diversion device remains in the forward flow position and the metering pump continues to operate f Reseal regulatory controls as necessary and record test results fot the office record Corrective Action If the booster pump fails to stop when the pressure differential is not maintained have the plant maintenance personnel or manufacturers service representative etc determine and correct the cause 274 PASTEURIZATION TESTING PROCEDURES 9 2 3 HHST AND ASEPTIC PROCESSING INTERWIRING OF THE PRESSURE DIFFERENTIAL
64. ENT FOR CONVENTIONAL TIMING PUMPS MAJ OR SALMONELLOSIS OUTBREAK IN CHICAGO SPAWNED INCREASED EMPHASIS ON MILK PROCESSING SANITATION BECAME KNOWN AS THE DAIRY INITIATIVES EMPHASIS PLACED ON IN DEPTH FDA AND STATE RATINGS INVOLVING DOWN TIME EQUIPMENT INSPECTIONS PRODUCT SAMPLING AND TRACING PRODUCT FLOWS TO EVALUATE POSSIBLE CROSS CONNECTIONS 24 BACKGROUND AND HISTORY 1986 LISTERIA OUTBREAKS IN CALIFORNIA FUELS FURTHER INVESTIGATIONS ON POST PASTEURIZATION CONTAMINATION PROBLEMS IN CHEESE AND MILK PLANTS COMPUTER CONTROLS ACCEPTED FOR MILK PASTEURIZATION SYSTEMS 1994 SALMONELLA OUTBREAK TRACED TO ICE CREAM PROBABLE ETIOLOGY WAS HAULING OF RAW LIQUID EGGS IN MILK TANKER WHICH WAS USED TO SUBSEQUENTLY HAUL PASTEURIZED MIX FREEZING AND PACKAGING WAS DONE WITHOUT RE PASTEURIZING THE MIX LARGE NUMBERS OF CULTURE CONFIRMED CASES 1994 CONTAMINATED WATER IN A PLANT WAS SUSPECTED CAUSE OF PACKAGED MILK TRANSMITTING COLI TO CONSUMERS IN MONTANA FAILURE OF WELL DISINFECTANT LED TO SUBSEQUENT CONTAMINATION OF PASTEURIZED MILK STORAGE TANK CULTURE CONFIRMED CASES PLANT CLOSED 25 BACKGROUND AND HISTORY THERMAL PROCESSING The term thermal process generally refers to a process during which a food product is subj ected to high temperatures with the objective of inactivating undesirable microorganisms or enzymes TYPES OF HEAT PROCESSING 1 PASTEURIZATION a Temperatures are generally below 212 F b
65. ESSURE The force exerted on an area by the column of air above that area Atmospheric pressure at sea level is 14 7 pounds per square inch BALANCE TANK Raw product tank located at the start of a pasteurization system used to maintain a constant supply of product to the pasteurizer BOOSTER PUMP A centrifugal pump placed in pasteurizing system between the balance tank and the raw regenerator and capable of producing positive pressure in the raw regenerator BOURDON COIL spring A sealed flat metal tube filled with a gas mixture that has been formed into a coiled spiral located inside the recorder controller This spiral expands or contracts in response to the vapor pressure of the gas mixture This coil is located on one end of the capillary tube with the recorder controller temperature sensing bulb at the other CMR A temperature recording device usually installed at the end of the cooler section a pasteurizer system providing constant record or milk temperature CAPILLARY TUBE A thin metal tube containing a mixture of liquids with low vapor pressures that connects the bourdon tube in the recorder controller with the temperature 338 sensor bulb located at the flow diversion device This thin tube is usually protected by a flexible metal cable CENTRIFUGAL PUMP A high speed pump that produces product flow due to the velocity increase of the liquid caused by the rotation of the pump impeller CONSTANT LEVEL TANK
66. EST RESULTS Recording Thermometer 3 months cate by Checked against Indicating Thermometer operator idu iod ER as cei diario fmm PE Device assembly microswotch single 3 months stem 5 4 Device assembly micro switches Dual 3 months stem ESE 0 mm I mmm 0 0 Jom Time Delay Inspect 3 months Time Delay CIP Time Delay LD Flush iid iid AS pom Indicating Thermometers in Pipeline 3 months HTST ONLY Thermometric Response Recorder Controller Thermometric 3 months HTST ONLY Response ee 2 2 pe rmm omm Hii ere pom 0n E Only Additional interwiring 352 Public Health Service MILK PASTEURIZATION CONTROLS TEST REPORT Food and Drug Administration 9 3 1 Booster pump interwired with FDD 3 months HTST ONLY 9 continued Booster Pumps Interwired with metering 3 months pump Milk flow controls cut in and cut out 3 months Daily by operator except HHST eee 1 Holding Tmeverttoaton 00000 TimeVerification 6 HTST except magnetic flow meter 6 months Adjusted product time if applicable systems ped Lic o gt EN idu fem O 2 Loss of signal low flow 6 months alarm HTST HHST and Aseptic Flow cut ES a iai T femmes e SA eem DT pec MAIS Direct Inf
67. EURIZERS Application All recorder controllers used in connection with HTST pasteurizers Frequency Upon installation and at least once each three months by the regulatory agency daily by the plant operator or when a regulatory seal has been broken Criteria No forward flow until pasteurization temperature has been reached Flow diverted before temperature drops below minimum pasteurization temperature Apparatus No supplemental materials needed Method By observing the actual temperature of the indicating thermometer at the instant forward flow starts cut in and stops cut out 280 PASTEURIZATION TESTING PROCEDURES Procedure a CUT IN TEMPERATURE 1 While milk or water is completely flooding the sensing element of the recorder controller and the indicating thermometer increase the heat gradually so as to raise the temperature of the water or milk at a rate not exceeding 0 5 C 1 F every 30 seconds If a water bath is used in place of water or milk flowing through the system the water bath shall be adequately agitated during this test 2 Observe the indicating thermometer reading at the moment the forward flow starts i e flow diversion device moves Note Observe that the frequency pen reading is synchronized with the recording pen on the same reference arc 3 Record the indicating thermometer reading on the recorder chart inscribe initials The regulatory agency shall record test findings b CU
68. LOPE UNCHANGEABLE FLOW DIVERSION DEVICE ASSEMBLY FUNCTION TIME DELAYS DIVERT LEAK DETECT LINE SLOPE BREAK AT BALANCE TANK VACUUM BREAKER PROPER LOCATION 60 Basic HTST Pasteurization HTST PASTEURIZATION 1 INTRODUCTION a Definition High temperature short time or HTST pasteurization is the process of heating every particle of milk product in properly designed and operated equipment to the minimum temperature requirement and held continuously at or above that temperature for at least the minimum time required For example Whole milk must be held at 161 F for 15 seconds while milk with higher milk fat content added sweeteners shall be heated to at gt 166 F and held for at least 15 seconds b HTST BASIC DESIGN AND FLOW PRINCIPLES Figure 9 1 COLD RAW MILK enters the constant level tank approximately 40 degrees and is drawn under reduced pressure into the regenerator section of the press 2 In the regenerator section the cold raw milk is pre warmed by the heat given up by the hot pasteurized milk flowing in a counter current direction on the opposite side of the milk to milk regenerator plates 3 The raw milk still under suction is drawn through a positive displacement timing pump which delivers it under positive pressure through the remainder of the HTST system 4 Under positive pressure the raw milk is pumped through the heater section where steam heated hot water on opposite sid
69. MUST BE A MINIMUM OF 12 INCHES ABOVE ANY RAW MILK IN THE SYSTEM 2 ALL DIVERT LEAK DETECTION AND RECYCLE LINES WHICH RETURN TO THE BALANCE TANK MUST BREAK TO ATMOSPHERE AT LEAST TWO PIPE DIAMETERS ABOVE THE OVERFLOW LEVEL 3 THE OVERFLOW LEVEL OF THE BALANCE TANK MUST BE LOWER THAN THE LOWEST RAW MILK IN THE RAW REGENERATOR Fig 32 Homogenizer as Non Flow Promoter Downstream from Heater Section 1 THIS LINE SHALL BE HORIZONTAL AT LEAST 12 INCHES ABOVE ANY RAW PIPING IN THE SYSTEM 2 ALL DIVERT LEAK DETECTION AND RECYCLE LINES WHICH RETURN TO THE CONSTANT LEVEL TANK MUST BREAK TO ATMOSPHERE AT LEAST TWO PIPE DIAMETERS ABOVE THE OVERFLOW LEVEL 3 THE OVERFLOW LEVEL OF THE CONSTANT LEVEL TANK MUST BE LOWER THAN THE BOTTOM OF THE INLET OF THE RAW REGENERATOR 5 REQUI RED WHEN HOMOGENIZER HAS GREATER CAPACITY THAN THE TIMING PUMP 133 ANY OTHER OMBINATIONS OR MODIFICATIONS WHICH ARE INSTALLED AND OPERATED IN ACCORDANCE WITH THE DETAILED PROVISIONS OF THESE PRACTICES MAY BE UTILIZED LEAK DETECT LINE FLOW a DIVE cuve t x REGENERATOR BY PASS OPTIONAL gt 4 RECYCLE Line 4 PRESSURE RELIEF VALVE 4 E p z z Figure 33 Homogenizer of smaller capacity than the Timing Pump 1 This line shall be horizontal at least 12 inches above any raw piping in HTST system 2 All divert leak detection and
70. Milk Specialist State Rating and Regulatory Officials and the milk industry for their support and contributions to the development of this manual CDR Robert F Hennes also assisted by providing much needed technical and grammatical editing Mr Steven T Sims FDA CFSAN Milk Safety Branch has also provided excellent detailed information on the inspection and testing of HHST UHT systems Others contributing technical information are Dr oseph Schlesser FDA CFSAN HACCP Division of Food Processing and Packaging Mr Richard Gleason California Department of Food and Agriculture and Mr Roger Krug of the Oregon Department of Agriculture provided technical suggestions and assistance The RED COW BOOK as it is presently known is to be used as a training and reference source It has evolved over the years as a result of previous milk training officers assigned to FDA s State Training Branch It was through the energies of individuals such as 1 Schlafman L Pool Roger Dickerson Jr Read Jr Robert B Carson Harold Tommy Thompson Harold Faig Ronald Smith O D Pete Cook Brenda Holman and others and under the direction and support of State Training Branch Directors such as J ames P Sheehy Harry Haverland and Gary E German that this manual has developed into its present form Providing much of the regulatory and practical aspects of inspecting and testing pasteurization systems were the FDA Regional Milk Specialis
71. PARTICIPANT REGISTRATION please print legibly COURSE TITLE MILK PASTEURIZATION CONTROLS AND TESTS 302 COURSE LOCATION DATE S NAME OB TITLE OB RESPONSIBILITIES ADDRESS WORK HOME WORK PHONE NUMBER NUMBER OF YEARS IN CURRENT PROFESSION DURING THIS COURSE WHICH AREA S WOULD YOU LIKE TO HAVE EMPHASIZED SPECIFIC QUESTION S THAT YOU WOULD LIKE TO HAVE ANSWERED DURING THIS TRAINING Mik Pasteurization Controls and Tests Course 302 STATE TRAINING BRANCH COURSE MANUAL 8th Edition 2003 Department of Health and Human Services Public Health Service Food and Drug Administration Division of Human Resource Development State Training Branch The purpose of this course is to develop and or increase the knowledge skills and proficiency necessary for the inspection and testing of milk pasteurization equipment Emphasis is given to the controls and tests necessary to assure effective pasteurization of milk and or milk products The course is designed to teach the public health reasons for the requirements which govern design function and operation of milk pasteurization equipment Richard D Eubanks CAPT United States Public Health Service Training Officer with edits by Ray Niles Gary German Director Food and Drug Administration Division of Human Resource Development State Training Branch 5600 Fishers Lane 11919 Rockville Pike Rockville MD 20857 Phone 301 827 8697 Note The
72. PERATURE ABUSE v COVERS IN PLACE DURING OPERATION v VAT CONSTRUCTION WITHIN COMPLIANCE AGITATION DURING OPERATION NO INGREDIENTS ADDED AFTER PAST EURIZAT ION v PRODUCT PROTECTED AFTER PAST EURIZATION 38 VAT PASTEURIZATION Figure 1 Schematic of a Vat Pasteurizer AIR SPACE HEATER AIR SPACE THERMOMETER INLET RECORDING THERMOMETER 39 VAT PASTEURIZATION BAT CH PASTEURIZER CONST RUCTION ST ANDARDS 1 Valves Outlet valves must comply with the close coupling standards established by the 3 A Standards a The valves must be constructed of solid stainless steel to permit adequate heat transfer to the inner portions of the valve and so designed as to prevent the accumulation of unpasteurized milk in the milk passages of the valve when the valve is in a closed position b All outlet valves must be of the leak protector type which are designed to prevent leakage of raw milk past the valve body The leak detector groove must be at least 3 16 inch in width and 3 32 minimum depth at the center to prevent clogging Note presently there are no air operated valves acceptable for use as vat pasteurizer outlet valves A limited number of cone bottom tank protector type valves were fabricated however their current availability is extremely limited These valves are designed with spiral shaped grooves designed which expel any leakages past the valve seat to the floor If cone bottom vats are u
73. Pa 10 psi above the boiling pressure of the product Procedure 1 From Figure 40 determine the pressure switch setting necessary for the operating temperature not the diversion temperature being used in the process 2 Install the sanitary pressure gauge of known accuracy and the pressure switch sensing element on the pneumatic testing device 310 PASTEURIZATION TESTING PROCEDURES 3 Remove the seal and cover to expose the adjustment mechanism on the pressure switch 4 Place the test lamp in series with the pressure switch contacts or use some other method to monitor the cut in signal 5 Apply air pressure to the sensing element and deter mine the pressure gauge Table 40 Pressure Switch reading at the cut in point of in the switch which will light Settings the test lamp If the switch is short circuited the lamp ii will be lighted before air pressure 5 pressure is applied Switch Setting PSIG AT 30 6 Determine that the cut in Sea Level pressure on the switch is equivalent to or greater than the required pressure from 191 210 230 250 270 290 Figure 40 Where Operating Temperature deg F adjustment is necessary refer to manufacturer s instruction After adjustment repeat the procedure set out in this paragraph 704 10 7 When the results are satisfactory seal the pressure switch setting and record the results for office record For each operating t
74. S ON PLUG VALVES 41 VAT PASTEURIZATION Figure 2 TYPE TYPE Figure 3 Close Coupled Outlet Valves VAT PASTEURIZATION 2 Covers a All openings must be provided with covers constructed to prevent the entrance of surface contamination or foreign material The main cover or lid shall be designed to remain in the open position to facilitate processing and or cleaning and shall be sufficiently rigid and self draining The main lid shall be designed so that raising will not allow any liquid or other contamination to enter the pasteurizer b Openings in the tank or vat cover must be equipped with raised edges to prevent surface drainage into the milk c The vat cover and any opening into the tank interior must have overlapping or shoe box type edges The covers must be relatively close fitting and overlap the opening d All pipe thermometer agitator shafts or other appurtenances that extend down into the vat must do so only through condensation diverting aprons unless a water tight joint is used 3 Agitators a All vats used for pasteurization must be equipped with a mechanical means of assuring that each and every particle of milk is heated This is accomplished by mechanical electrical motor driven agitators The most efficient agitators will be designed to push the product down and sweep the product across the heat exchange surface on the sides and bottom of the vat Agitators shall be designed t
75. S require verification only one time at the factory EPROMS EEPROMS and EAPROMS require verification each time the unit is sealed RAMS computer disks and or tapes are NOT ACCEPTABLE to operate computerized public health controls for pasteurizers 366
76. T Auxiliary Equipment The differential pressure controller utilizes two sanitary pressure sensors The raw sensor is located between the discharge side of the booster pump and the entrance to the raw regenerator and the pasteurized sensor is located at the outlet of the pasteurized regenerator The controller is interwired with the booster pump and permits it s operation only when the pre set pressure differential is satisfied 3 Stuffer product and feeder pumps This is the term used for centrifugal pumps placed elsewhere in the System to either feed stuff or remove product from processing auxiliary components The use of stuffer pumps are common to feed product to separators vacuum chambers and homogenizers in most pasteurization systems In the magnetic flow timing systems centrifugal pumps are used as the timing pump Meter based timing systems are discussed in detail in a later chaper It is very common to see stuffer pumps feeding product to homogenizers used as timing pumps In this installations the stuffer must always be interwired with the homogenizer to prohibit operation unless the homogenizer is operating In fact all flow promoters in the HTST system are only allowed to operate in conjunction with the timing pump Product removal pumps or tail pumps are used to remove product from flavor enhancing equipment vacuum chambers The only difference between any of the above uses of these pumps and booster p
77. T OUT TEMPERATURE 1 After the cut in temperature has been determined and while the milk or water is above the cut in temperature allow the water to cool slowly at a rate not exceeding 0 5 C 1 F per 30 seconds Observe indicating thermometer reading at the instant forward flow stops 2 Reseal the regulatory controls as necessary and record the indicating ther mometer reading on the recorder chart and initial Corrective Action Should the reading be below the minimum pasteurization temperature the cut in and cut out mechanism and or the differential temperature mechanism should be adjusted to obtain proper cut in and cut out 281 temperatures by repeated tests When compliance is achieved seal the controller mechanism 10 2 HHST PASTEURIZERS AND ASEPTIC PROCESING SYSTEMS USING INDIRECT HEATING Application All HHST pasteurizers and aseptic processing systems using indirect heating When testing aseptic processing systems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in this test Frequency Upon installation and every 3 months thereafter whenever the thermal controller seal is broken Criteria The pasteurizer or aseptic processor shall not operate in forward flow unless pasteurization or aseptic processing temperature has been achieved The product flow shall be diverted at a temperature no lower than the cho
78. Y DR S NORTH AND PACK DEVELOPING TEMPERATURE DESTRUCTION CURVES RELATIVE TO MYCOBACTERIUM AND TUBERCULOSIS 1924 THE USPHS CREATED THE OFFICE OF MILK INVESTIGATIONS UNDER THE STRONG LEADERSHIP OF LESLIE CARL FRANK 23 1924 1941 1952 1953 1955 1956 1966 1978 1979 1985 BACKGROUND AND HISTORY THE STATE OF ALABAMA WORKED CLOSELY WITH THE USPHS TO DEVELOP THE FIRST FEDERAL MILK ORDINANCE PATTERNED AFTER THE ALABAMA STANDARD MILK GRADING ORDINANCE PYREX HEAT RESISTANT GLASS PIPING USED IN DAIRY INDUSTRY ASA MEANS OF CONSERVING CRITICAL MATERIALS DURING WARTIME SEVERAL STATES MET IN ST LOUIS TO DISCUSS THE PROBLEMS OF RECIPROCITY FOR SHIPPING MILK ACROSS STATE LINES THIS WAS THE FIRST NATIONAL CONFERENCE ON INTERSTATE MILK SHIPMENTS ALSO MUCH RECOGNITION TO DR C A ABELE AND DR EVERETT WALLENFELDT FOR THEIR EARLY PIONEERING EFFORTS IN THE DEVELOPMENT OF THE GRADE A MILK PROGRAM THE FIRST 3 A STANDARD FOR CIP CLEANING WAS PUBLISHED THE FIRST AUTOMATED CIP SYSTEM INSTALLED IN AN OHIO MILK PLANT MINIMUM TEMPERATURE FOR VAT PASTEURIZATION WAS RAISED FROM 142 F TO 145 F BASED ON HEAT RESISTANCE OF Coxiella burnetti BASED ON UNIVERSITY OF CALIFORNIA DAVIS STUDIES IN LATE 1940 S FDA MEMORANDUM ACCEPTS DUAL STEM CIP FLOW DIVERSION DEVICE TO BE USED IN HTST SYSTEMS FIRST U S UHT STERILE MILK SYSTEM COMMISSIONED IN GEORGIA MAGNETIC FLOW METER SYSTEMS FOUND ACCEPTABLE FOR USE AS REPLACEM
79. a HTST system MICROSWITCH A mechanically activated electric NO normally open NC normally closed switch It is a small level actuated switch used in the control circuit and is sometimes referred to as a limit switch Microswitches may have three terminals one to supply current and the two others are marked no for normally open and NC for normally closed External pressure on the lever will change the position from NO to NC or vice versa depending on the switch wiring Used to break or make a control circuit PMO The current edition of the Pasteurized Milk Ordinance PNEUMATIC Operated by compressed air PRESSURE RELIEF VALVE A valve which is designed to automatically open when subjected to the determined pre set pressure AKA pop off valve REGENERATOR BY PASS VALVE A automatic or manually controlled valve used in combination with the booster pump for the purposes of start up of a continuous pasteurizer with a milk to milk regenerator This valve allows for by passing the regenerator in order to provide the proper pressure relationships in the regenerator thus allowing the booster pump to operate 340 SANITIZATION The application of any effective method or substance to a clean surface for the destruction of pathogens and of other organisms as far as is practicable Such treatment must not adversely affect the equipment the milk or milk product or the health of consumers Sanitization may be accomplished b
80. actor same value as determined in Test B ee a ae 2 2 I lt w Record programmed process values for the office record 4 Seal the back panel the recorder controller CORRECTIVE ACTION If any of the programmed process values can be altered see vendor s manual with the control switch in the locked position contact the vendor for repairs or replacement of the recorder controller If any of the programmed process values a through j do not have the values shown in this test repeat Test A 319 CASE STUDIES 321 CASE STUDIES CASE STUDIES IN THE DESIGN INSTALLATION AND OPERATION OF HTST PASTEURIZATION SYSTEMS PURPOSE The purpose of these case studies are to provide the participant with some guidance and insight into milk flow sequences within a pasteurization system Also this should to give the participant an opportunity to make determinations for the placement of public health controls in various systems METHOD Using the list of pasteurizer components provided on the following page and your assigned case study construct an acceptable flow diagram showing the proper location of each component in the system including the following parameters 1 The effects that your flow arrangement has on the TIME TEMPERATURE PRESSURE relationship within the system 2 The flow promoting equipment operational requirements during divert shut down inspect
81. acy on the pneumatic testing device to which the pressure switch sensing element should also be connected 2 Remove the seal and cover to expose adjustment mechanism on pressure switch 3 Operate the testing device and determine the pressure gauge reading at the cut in point of the pressure switch which will light the test lamp If the switch is short circuited the lamp will be lighted before air pressure is applied 4 The cut in point should be adjusted if necessary so asto occur at a pressure gauge reading at least 6 9 kPa 1 psi greater than the maximum booster pump operating pressure as determined under section a of this method Where adjustment is necessary refer to manufacturer s instructions for adjusting procedure After adjustment recheck actuation point and readjust if necessary 5 Replace cover and seal the pressure switch and restore sensing element to original location 6 Record test results for the office record 269 9 2 DIFFERENTIAL PRESSURE CONTROLLER Application Part 2 1 applies to all differential pressure controllers used to control the operation of booster pumps on HTST and HHST systems or used to control operation of flow diversion devices on HHST and aseptic processing systems when no vacuum breaker is located downstream from the holding tube Part 2 2 applies only to HTST systems Part 2 3 applies to the testing of HHST systems in which the differential pressure controller is used to con
82. als The purpose of this is to allow for inspection of the tube for proper slope and to detect any unauthorized changes in length 73 The Official Thermometer E INDICATING THERMOMETER 1 Purpose To indicate the accurate temperature of the product 2 Location At the end of the holding tube and as close as practical to the recording thermometer sensor 3 Specifications a Type mercury actuated direct reading corrosion resistant case b Scale Span not less than 25 F including pasteurization temperature plus or minus 5 F graduated in 0 5 F divisions c Accuracy 0 5 degrees F plus or minus throughout scale d Thermometric response 4 seconds to travel 63 12 degrees which includes the pasteurization range of a 19 degree span e Type electronic On November 27 1991 the FDA s Milk Safety Branch through M b 314 allowed the use of the digital reference thermometer DRT as a replacement for the mercury actuated MIG indicating thermometer for use pasteurization systems 74 Basic HTST Pasteurization The Anderson and Taylor Companies offer the digital reference type thermometer analogue type which uses a dual wound sensor on the 1000 ohm RTD sensor device Differences in resistance resulting from temperature changes are converted directly to a temperature value which is displayed on the panel Fail safe operation of the DRTs is accomplished by using two separate resist
83. ance temperature devices RTD s If the two RTD s read more than 0 5 degrees F difference the display blanks out making it impossible for the operator to observe the temperature Testing of the DRT is identical to conventional tests as described in Test 1 and 7 of Appendix of the PMO and some additional guidelines may be helpful in the DRT instruction manual for performing these tests Because of the self diagnostic circuitry the thermometric response test is required as with mercury actuated type thermometers 1 93 1 issued April 18 1993 provides specific criteria for evaluation of the new digital thermometers These criteria are 1 No more than 0 5 F 0 25 C drift over 3 months use on an HTST system compared to a certified thermometer 2 Readout is displayed in units of temperature with at least count of 0 1 F 3 Display changes at a rate that can be noted by the operator or public health authority during the thermometric lag test Test 7 Grade A PMO 75 4 Self diagnostic circuitry which provides constant monitoring of all input and conditioning circuits The diagnostic circuitry should be capable of detecting open circuits short circuits poor connections and faulty components Upon detection of failure of any component the device shall blank or become unreadable 5 The effect of electrical noise shall be documented and available to public health authorities Protocols for these tests shall be de
84. andard is 204 F for 0 05 second The holding tube is 3 inches in diameter and 6 inches long The pumping rate is calculated from Equation 1 A BxC The holding tube length A is 6 inches and from Table 1 the holding tube length required for a holding time of 0 05 second with a pumping rate of 1 gallon per second in 3 inch diameter tubing is 4 inches For this example 6 Bx4 6 4 Therefore B 1 5 gallons per second The maximum permissible pumping rate is 1 5 gallons per second At this pumping rate the time required to fill a 100 gallon vat is 100 gallons divided by 1 5 gallons per second or 66 6 seconds INSTRUMENTATION AND REGULATORY CONTROLS 206 HHST UP AND UHT SYSTEMS Steam injection systems require a greater amount of instrumentation than do conventional systems This is because of the following factors 1 Steam injection is inherently an unstable process 2 Microorganism lethality occurs in the holding period 3 Holding tube lengths for most systems are sometimes short and 4 Sterility must be assured after each diversion In addition there is the product adulteration problem that must be dealt with During pasteurization using direct steam addtition product may be diluted with water condensed steam by 1 for every 10 temperature increase by steam injection REGULATORY CONTROLS REQUIRED HHST WITH DIRECT STEAM HEATING 1 Safety Thermal Limit Controller with three 3 sensors lo
85. ant the flow diversion device takes the fully diverted flow position Procedure a With water bath or oil bath at a temperature above cut out temperature allow the water or oil to cool gradually At the moment the cut out mechanism is activated start the watch and the moment the flow diversion device takes the fully diverted position stop the watch b Record results c Re seal regulatory controls as necessary Corrective Action Should response time exceed 1 second immediate corrective action must be taken 255 5 7 TIME DELAY INTERLOCK WITH METERING PUMP Application To dual stem flow diversion devices with a manual forward flow switch INSPECT position on the mode switch Apparatus None Method Determine that the device does not assume a manually induced forward flow position while the metering pump or other flow promoting devices capable of causing flow through the holding tube is running Procedure With the system running in forward flow move the control switch to the Inspect position and observe that the following events automatically occur in sequence a The device immediately moves to the diverted flow position and the metering pump and all other flow promoting devices are turned off or in the case of separators are effectively falved out of the system b The device remains in the diverted flow position while the metering pump and all other flow promoting devices are running down or in the case of separa
86. aratus A stopwatch Method Observe the movement of the divert and detect valves to the forward flow positiojn and measure the time interval between the movement of the two valves Procedure 259 1 Move the flow diversion device from the diverted flow position to the forward flow position either by raising the temperature above the cut in set point or by operating the HTST pasteurizer above the cut in temperature in manual divert mode and releasing the manual divert activating NO push button or switch 2 When the divert valve begins to move to the forward flow position start the watch 3 When the leak detect valve begins to move to the forward flow position stop the watch 4 Record the elapsed time 5 If the elapsed time is at or above one second all systems and at or below five seconds meter based systems or non restricted divert lines systems not applicable seal the time delay Corrective Action If the elapsed time is less than one second or greater than five seconds appropriate changes to the system or system controls must be made 260 PASTEURIZATION TESTING PROCEDURES TEST 6 LEAK PROTECTOR VALVE BATCH PASTEURIZERS Reference Item 16 Application To all batch vat pasteurizer outlet valves Frequency Upon installation and at least once each 3 months thereafter Criteria No leakage of milk past the valve seat in any closed position Apparatus No supplementary materials required
87. aratus For all flow diversion devices including both single and dual stem types Suitable tools are necessary for the dissasembly portion of this test Method Observe leakage past the valve seat s for the single stem or the leak detect valve piping dual stem of the flow diversion device for leakage Procedure With the system operating with water place the flow diversion device in diverted flow position A For Single Stem Valves disconnect the forward flow piping and observe the valve seat for leakage Check leak escape ports to see if they are open 244 PASTEURIZATION TESTING PROCEDURES B With the dual stem device observe the leak detect line discharge or sight glass for leakage Corrective Action If leakage is noted device must be dismantled and defective gaskets replaced new plugs valve stem plugs installed or other suit able repairs made 5 2 OPERATION OF VALVE STEM S Apparatus Suitable tools for tightening single stem packing nut and as necessary tools for dissembly of some dual stem flow diversion device stem s and actuators and other sanitary piping wrenches Method Observe flow diversion device valve stem s for ease of movement Procedures When a stem packing nut is used tighten stem packing nut as much as possible Operate system place device in forward and diverted flow several times Note freedom of action of valve stem Corrective Action If valve action is sluggish suitable adjustmen
88. asteurization Figure 18 Anderson STLR Wiring Diagram INSTRUMENT POWER SUPPLY ONLY 120 VAC 60 Hz or 240 VAC 6OHz CHECK INSTRUMENT NAMEPLATE TIMING PUMP STARTER RELAY FLOW DIVERSION SOLENOID BOOSTER PUMP PRESSURE SWITCH STARTER RELAY FUSE RATING REQUIRED Fuse 122 240V ri jas 125 F2 JUMPER 125 F3 JUMPER 15 Fa 15 __ 91 SANITARY DIFFERENTIAL CUSTOMER MAY TUNE TO SUIT 7 F DEAD BAND DECREASES ACTIVATION TEMP OF CUT OUT RELAY ON GREATER URN TURN FACTORY SET RANGE JUMPER LEFT TO RIGHT A 190 to 220 a 150 to 175 BOTTOM OF RANGE 90 to 120 OF CHART SELECTED nz CUSTOMER ADJUSTABLE 5 to 30 SET POINT TEMP CUT OUT SET POINT ADJUSTMENT FACTORY FACT e p NORMAL POSITION FOR CHART 190 290 220 320 SHUNT NORMAL POSITION 120 220 SE PONT CARD SET 29IN7 CARD Figure 19 Anderson STLR Set Point Calibrations 92 Basic HTST Pasteurization HONEYWELL ELECTRONIC STLR BASIC DESCRIPTION This is a microprocessor based circular chart recorder which has the unique function of style print head which will print up to four analog traces signals on a blank heat sensitive chart The chart parameters are key controlled and include chart range speed alarm set point etc All public health programs are protected from
89. at treating now being called pasteurization milk Milk as nature s most perfect food is therefore also a perfect medium in which bacteria can thrive Realizing this attribute many states Illinois being one began to develop laws regarding the tuberculin testing of dairy herds and restricting milk sales to those herds which had been tested In 1914 New York City required by law that all milk sold must be pasteurized In 1920 the American Public Health Association s Committee on Milk Supply reported 13 BACKGROUND AND HISTORY almost 4200 milk plants failed to meet even minimum milk pasteurization standards Following engineering studies known as the Endicott Experiments since they were conducted in Endicott N Y conducted by Dr Charles E North of the North Public Health Bureau and the Borden Farm Products Company the Public Health Service published a bulletin no 147 attesting that there were indeed MAJ OR improvements necessary to protect the public health and assure a milk product free of pathogens Perhaps the single most contributing factor to the public health regulatory control of milk pasteurization and safety occurred in 1924 when the state of Alabama initiated a request for assistance from the U S Public Health Service to develop a milk sanitation program The work between this state and the federal government eventually led to the development of the first proposed Standard Milk Ordinance November 7 1924 Publ
90. ated switch located on the input output bus that instructs the computer to place all outputs in the on or off or last state during a start up The last state position instructs the computer to place the outputs in whatever state on or off occurred during the last loss of power Operator override switch A manually operated switch located on the input output bus that permits the operator to place any input or output in the on or off position independently of any program instructions Output Electrical signals from the computer that turn on or off valves motors lights horns and other devices being controlled by the computer Outputs may also consist of messages and data to the operator Programmable controller A computer with only limited mathematical ability that is used to control industrial machines instruments and processes Most computers used on HTST pasteurizers will be programmable controllers RAM Random access memory A memory used by the computer to run programs store data read input and control outputs The computer may either read the memory or write data into the memory 358 ROM Read only memory A memory used by the computer to run its own internal unchangeable programs The computer may only read from the memory it cannot write in to the memory or alter the memory in any way Standby status the computer is turned on running and waiting for instructions to start processing input data This instru
91. ators 155 B Types of Systems 1 Single chamber vacuum sytem with no adition of steam installed upstream of the heater section HOLDING TUB Figure 46 Vacuum chamber on raw side with no steam addition 156 HTST Auxiliary Equipment CHECK VALVE VACUUM CHAMBER 11 BACK PRESSURE i J ema es BACK DIVERSION CONTROLLER Re J Vi ACUUM BPC D BREAKER BREAKER DEVICE my 1 STLR 9 a LEAKADETECT LINE we Ln AG BREAKER PASTEURIZED PRODUCT COOLER REGENERATOR 1 m JV SIGHT fo v RECYCLE LINE GLASS LL RECYCLE LINE ____ e 3 Y On DRAIN RAW PRODUCT m TIMING PUMP Figure 47 HTST with vacuum system located downstream from flow diversion device no steam added BACK PRESSURE DEVICE es AND VALVE a 7 m VACUUM d sry BREAKER a PASTEURIZED PRODUCT HOLDING TUBE 4 4 RAV DRAIN SEPARATOR FEED M A 90 2 974 CULINARY STEAM DIRECT STEAM HEATER SUPPLY SHUT OFF AND PUMP LEVEL CONTROL VALVE RETURN Y RAV CREAM DUT 4 1 BACK PRESSURE VALVE Figure 48 HTST system with raw separation and vacuum chamber with direct addition of steam 158 HTST Auxiliary Equipment VACUUM CONTROL VALVE VACUUM CHAMBER BACK PRESSURE CONTROL DEVICE DIRECT STEAM HEATER 1 11
92. ature sensor in a water bath at atemperature 7 F above CUT IN and accurately determine the elapsed time when the temperature rises from a point 12 F below CUT IN to the time of CUT IN which accurately times the thermometric response for pasteurizer recorder controllers 15 When the computer prints the frequency pen position the position of the flow diversion device forward or divert at specific intervals rather that continuously all changes of position shall be recognized by the computer and printed on the chart In addition the frequency pen position and temperature in the holding tube must be printed on the chart ina manner that the temperature in the holding tube can be determined at the moment of a change of position of the flow diversion device 362 16 The vendor shall provide a built in program for test procedures or a protocol shall be provided so that all applicable public health tests of Appendix for each instrument can be performed by the Regulatory Official i e RECORDING THERMOMETER Temperature Accuracy Time Accuracy Daily accuracy check against indicating thermometer Thermometric Response FLOW DIVERSION DEVICE Valve seat leakage Operation of valve stem s Device assembly Manual diversion Response time time delay intervals if used BOOSTER PUMP Proper wiring proper pressure control settings FLOW PROMOTING DEVICES Holding time Auxiliary separator product pumps Proper wiring interlocks 17 Com
93. be itself Further the milk in the central portion of the holding tube will move ata greater velocity than product nearest the tube wall which moves at slower rates These wide variances in flow rates causes concern over the assurance of meeting minimum legal holding times Laminar flow is best described as the variances in product flow profiles through uniform sized length of piping Studies by Knudson and Katz in their 1958 involvement with fluid dynamics and by R Dickerson and A Scalzo 1968 in evaluating residence times of milk products in holding tubes have shown that the central portion termed the parabola will traverse through the holding tube at sometimes twice the velocity as the surrounding product These variances in flow rates were accomplished using trace measurements of radioactive iodine Using Reynolds number formulation determinations were made to postulate water flow variances at 18 less than average time while milk flow variances were 50 less than average time This flow condition is greatly influenced by product viscosity which unlike water which produces turbulent flow product will produce a laminar flow in which the maximum velocity is assumed to equal twice the average velocity In another study by Jordan and March it was demonstrated that the variance between fastest and slowest particles was as much as 10 seconds in a 15 second holding tube It is also interesting to point out that among the products tested skim
94. ble to provide maximum reacabiity optionally in the produci range while including CIP temperature The standard color for this variable is blue Finally the unit wil soon be available with a Salely Flow Limit function for systems with meter based timing This option can include Recording SFLA or Recording and Control SFLRC Range can be configured in parcent flaw ar engineering units GPM The standard color for this function is black 94 Figure 20 Honeywell STLR 95 Note These tests are required upon installation and quarterly thereafter or when any regulatory seal is broken Tests 2 3 and 8 are required as is Tests 4 and 10 With the earlier models of this STLR as with the first model of the ABB Kent Taylor the recording temperature is not adjustable as with conventional systems and requires the breaking of regulatory seals 5 Recording Thermometer Charts a All charts used for the pasteurization of milk must contain all the following information Plant name and location Date Identification of pasteurizer if more than one Name or initials of operator Cut in and Cut out temperatures as checked at start of day s production 6 Reading of indicating thermometer at a specific 7 Amount and identity of each product in the run 8 Record of any unusual occurrences 9 Record of the position of the FDD 5 1 2 3 4 5 b Charts must be neat and legible and contain NO o
95. button This should 1 Cause the valve to assume the divert position and 2 de energize the booster pump the pressure differential between raw and pasteurized milk in the regenerator should be maintained b Operate the HTST system at its maximum operating pressure and ac tivate the manual divert button Confirm that the spring tension of the flow diversion device is still capable of diverting the system at maximum operating pressure C Operate the HTST system in forward flow and activate the manual divert button until the raw pressure reaches zero 0 psi Deactivate the manual divert button and observe the raw milk and pasteurized milk pressures The pressure differential between raw and pasteurized milk in the regenerator should be maintained Corrective Action If the above described actions do not occur when procedures a b and c are performed or the necessary pressure differential between raw and pasteurized milk is not maintained the assembly and wiring 253 of the HTST system must be immediately reviewed and the indicated deficiencies corrected or proper adjustments made 254 PASTEURIZATION TESTING PROCEDURES 5 6 RESPONSE TIME Apparatus STOPWATCH The stopwatch should be used to determine that the response time interval does not exceed 1 second Method Determine the elapsed time between the instant of the activation of the control mechanism at cut out temperature on declining temperature and the inst
96. case should this time exceed 4 hours Following pasteurization the product must be cooled to lt 45 F as soon as possible The only exception for this cooling requirement is for cultured products processing 3 If for any reason the vat lid or any cover is lifted or mechanical failure of any kind agitator malfunction loss of temperature below the required minimum etc occurs after beginning of the pasteurization cycle the timing process must be restarted and notes to that effect must be made on the recording chart by the operator 49 VAT PASTEURIZATION 4 The official thermometer is the indicating thermometer and the recording thermometer functions to only provide a record of the pasteurization cycle For each product batch the operator is required to verify the accuracy of the recording thermometer using the indicating thermometer as the standard This comparison is noted on the recording thermometer chart No batch of milk shall be pasteurized unless the sensors of both thermometers are covered 5 The air space thermometer reading must also be recorded on the recording chart during pasteurization To assure that the minimum air space temperatures are being maintained the air space indicating thermometer shall be read and recorded at the beginning of the holding period It is also strongly recommended that the air space temperatures be noted and recorded during and at the end of the holding period During pasteurization the ai
97. cated a At end of the holding tube b In the coolest part of the vacuum flash chamber and J ust prior to the flow diversion device 2 Ratio Controller 207 A ratio controller is required for systems applying direct steam to product to prevent water adulteration of the product This ratio controller is interlocked with the vacuum pump steam controller and automatically monitors and controls the amount of vacuum applied and or the amount of steam injected This is accomplished by constantly monitoring the product temperature at the inlet and outlet of the chamber One sensor is located immediately prior to the point of steam injection and the other is located immediately after the product exits the vacuum chamber Ideally the product temperature at the exit point of the vacuum chamber should equal the inlet product temperature measured prior to steam injection or infusion less any product heat loss by heat radiating from the equipment This determination is achieved by each individual processing plant based on a series of product analysis for total solids added water and other applicable laboratory methods Usually a system of trial and error is used for this determination Individual plant ratio controller s temperature differential set point may be slightly dissimilar depending the total solids composition of the raw milk source and variances in equipment installations When a water feed line is connected
98. cated at its coolest part When installed in this vacuum condenser line as in most cases it shall be 212 HHST UP AND UHT SYSTEMS positioned at the point of downward slope back towards the condenser or vacuum pump The newly designed internal pass type vacuum chamber as in the Tetra Pak system s would require positioning the outlet temperature controller sensor where the condenser tube exits the chamber at the bottom This will assure that the sanitization temperature in the chamber achieves the minimum required pasteurization temperature You may note that in this type of vacuum chamber the milk also enters at the bottom and exits at the bottom Without the sensing element positioned in the coolest part of the vacuum chamber product could be above the required temperatures in the holding tube cooled to sub legal temperatures in the vacuum chamber and reheated to the required temperature in the regenerator Please do not confuse these controller sensors with the ratio controller sensors Pressure Limit Controllers Product pressures in the holding tube and across the steam injector are monitored and controlled to keep the product in the liquid form and to ensure adequate isolation of the injection chamber This instrument must have a pressure switch so that the flow diversion device will move to the divert position if the product pressure falls below 10 psi of the boiling pressure of the product Example for operating tempe
99. condensed milk exhibited the shortest residence times differing from a fully developed laminar flow by only lt 8 117 CENTRAL CORE OF FLUID LAMINAR MOTION OF FLUID IN A HORIZONTAL ROUND PIPE Figure 26 Laminar Flow For the above reasons the requirement that holding time tests performed on conventional gear driven impeller timing pumps must be converted to calculated product holding times using water vs product measured pumping rates Continuous pasteurizers using homogenizers operating at 2120 minimum required holding times and all meter based magnetic flow timing systems are exempt from this calculated holding time requirement Laminar flow must be considered when calculating holding tube lengths and most significantly those used in Ultra High Temperature Pasteurization Calculations are made using the following equation L 588 Qt D Where L holding tube length Q pumping rate gallons t holding time standard second D inside diameter of holding tube 118 DIVERTED FLOW FREQ PEN ARM 2 BOURDON SPRING DIAPHRAGM SUPPLY TEMPERATURE SENSOR RECORDER CONTROLLER FLOW DIVERSION DEVICE 1 MILK TEMPERATURE GELOW CUT IN SETTING 1 FDY SIMENINB ENERGIZED 2 EXPELLED T WASTE THROUGH NOZZLE 2 IHCERSWITCH MOLLER CENTERED IN PUSH PLATE 3 MICROSWITCH CONTACT NC CLOSED 4 WO CURRENT TS FRY SOLENSID MICROSWITCH CONTACT PROVIDES CURRENT TO 5 WO
100. ct Homogenizers are capable of producing great pressures for the homogenization of milk and milk products usually in the range of 1200 to 3000 psi Homogenizers are available using either a one or two stage homogenizer valve The average size of a fat globule is around four 4 microns Most homogenizers accomplish a 10 1 micron reduction in size when properly operated Homogenization also requires the fat to have been warmed to a liquid or oil phase Homogenizers are sometimes of the belt driven variable pulley type and two speed motors are not uncommon Since it is veritably impossible to synchronize two positive pumps measures must be taken to assure proper operation of homogenizers installed in systems using gear driven timing pumps 131 2 Application in the HTST system Homogenizers are always considered as positive displacement pumpsd or flow promoting devices therefore consideration must be given to their placement in the system 3 The regulatory controls necessary for homogenizers are as follows a When installed on the raw side of the HTST system the homogenizer must be designed installed and operated as a non flow promoting device unless used as the timing pump Figure 31 shows the homogenizer installed with a non restricted recirculation line 5 with an optional by pass line 4 used when homogenization is not desired b Figure 32 shows the homogenizer installed after the heating section A one way sanitary chec
101. ction is usually accomplished by a manually operated switch Status printing Some computers are programmed to interrupt printing of the chart record and print the status of the set points and conditions such as cold milk temperature holding tube temperature diversion temperature setting and chart speed 359 CRITERIA The following listed criteria shall be complied with for all computers or programmable controllers when applied to HTST HHST and pasteurization systems used for Grade A milk and milk products In addition all systems shall conform to all other existing requirements of the Grade A Pasteurized Milk Ordinance 1 A computer or programmable controller used for public health control of Grade pasteurizers must be a system dedicated only to the public health control of the pasteurizer The public health computer shall have no other assignments involving the routine operation of the plant 2 The public health computer shall NOT be under the command or control of any other computer system It shall not have an address to be addressable by any other computer system A host computer cannot override its commands or place it on standby status All e output addresses of the public health computer must be ready to process ma date at any time 3 separate public health computer must used each pasteurizing system 4 The status of the Input Output bus of the public health co
102. d between the pasteurized milk outlet of the regenerator and the vacuum breaker 7 Raw milk must enter at the bottom of the regenerator unless properly installed regenerator by pass is installed and must be able to drain freely back to the balance tank during periods of shut down or loss of power This is facilitated through the small drilled holes in the bottom of the raw milk regenerator To facilitate this the outlet to the raw milk regenerator should be disconnected COVER 2722727222222222222 STEM with 07 Ring SEAT CONNEC TION E Sanitary Vacuum Breaker Figure 25 113 PRESSURE RELIEF VALVES LOCATED WITHIN HTST HHST AND ASEPTIC PROCESSING SYSTEMS Pressure relief valves are allowed between the Timing Pump and the beginning of the Holding Tube if a The pressure relief valve is a fail safe spring to close valve with a spring pressure greater than the highest normal operating pressure of the system when operating in Product mode or a fail safe spring to close valve with overriding air pressure b Provisions are made for cleaning the valve whenever the system is cleaned Except as provided above if pressurized air is used to overcome the pressure relief valve spring the flow of this air must be enabled only in CIP mode after the minimum required ten 10 minute time delay relay has expired If a computer controls the air that computer must comply with the requ
103. de that the logarithm of the D value was linearly related to temperature The figure relating log D to temperature is call the thermal death curve This is an extremely significant observation in the development of thermal process calculations because the thermal death time curve or the equation which describes it provides a means for equating various time temperature treatments in terms of thermal destruction of microorganisms or spores Knowing this and the temperature history of the product the thermal process which will inactivate a given load of vegetative organisms and spores can be established According to the logarithmic order of bacteria by exposure to lethal heat it follows that it is not possible to completely inactivate a given population of an organism in a milk sample of infinite size as in encountered with continuous flow milk pasteurization Therefore to obtain process standards an arbitrary D 29 BACKGROUND AND HISTORY value must be established for achieving unit lethality PASTEURIZATION What is it The application of a heat process to good quality milk for the purpose of rendering it a safe and nutritious food product which will survive on the shelf for a ten to 20 day period under refrigerated conditions has been the industry standard for over 5 decades Pathogens are destroyed industry and the consumer are happy and healthy and the nation s milk supply is safe and wholesome Pasteurization has been descr
104. device When proper cut out temperature has been verified for both sensing elements seal the controller system 10 3 HHST PASTEURIZERS AND ASEPTIC PROCESSING SYSTEMS USING DIRECT HEATING Application All HHST pasteurizers and aseptic processing systems using direct contact heating When testing aseptic processing systems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in this test Frequency Upon installation and every 3 months thereafter whenever the thermal limit controller seal is broken Criteria The pasteurizer or aseptic processorshall not operate in forward flow unless pasteurization or aseptic processing temperature has been achieved The product flow shall be diverted at a temperature no lower than the chosen pas teurization or aseptic standard Apparatus No supplemental materials needed Method The cut in and cut out temperatures are determined by observing the actual temperature in the constant temperature bath at which each of the three sensing elements signals for forward flow cut in and diverted flow cut out 283 Procedures a Wire the test lamp in series with the control contacts of the sensing element the holding tube Immerse this sensing element in the constant temperature bath Raise the bath temperature at a rate not exceeding 0 5 C 1 F every 30 seconds Observe the tempera
105. diameters above the overflow level 3 the overflow level of the constant level tank must be lower than the bottom of the inlet of the raw regenerator 14 the safety thermal limit recorder stlr recorder controller for this system must have three sensing elements at the discharge end of the holding tube in the top of the vacuum chamber and at the common port of the flow diversion device the product temperature in the holding tube and the position of the flow diversion device frequency pen must be recorded on the main recorder controller while the other two sensing elements may be interlocked with the main recorder controller through auxiliary indicating controllers other combination or modifications which are installed and operated with the above and with the detailed provisions of these practices may be utilized 210 HHST UP AND UHT SYSTEMS Figure 60 Steam Injection Pasteurization Controls HHST with Steam Injection Vacuum Cooling and Flow Diversion Device at End of System 211 Before the system can be allowed to go into forward flow product fluid temperatures at all three sensing elements must simultaneously be at or above the minimum pre set pasteurization temperatures for the minimum time required AND proper pressure relationships in the milk water milk regenerators must be satisfied In HHST systems the booster pump is allowed to operate at all times When the proper pressures however are not met 1 The system
106. differential pressure across the valve is 30 psig or greater The design of the valve allows closing against the process flow rather than with the flow as do conventional valves Drainage between the two valves is accomplished through a tangential connecting line between the two valve bodies Two piece stems allow for assembling and disassembling the valve and are joined together with a nut and 0 ring seal In case of o ring failure leakage flows through leak detect ET D 4 holes in the short stem and is visible through clear plastic stem gu FDD and its components are shown in the following illustration EM gt ard This Reverse acting FDD figure 24a 107 3 Basic Requirements a Systems shall be designed to assure proper operation of the flow diversion device only when properly assembled and only when in the fully forward or fully diverted position b It must be impossible to tighten the stem packing so as to prevent the valve from assuming the fully diverted position within the prescribed time lt 1 sec c The length of the connecting rod shall not be adjustable d Power failure or loss of air pressure shall automatically move the valve to the fail safe diverted position The flow diversion device shall be located downstream from the holding tube and indicating and recording thermometer sensors f The divert line shall be self draining and shall be free of restrictions or valves unless
107. ding installation and culinary steam requirements The air space heater must be easily demountable for cleaning See Appendix H of the PMO for culinary steam requirements or Figure 5 below STEAM STEAM SN STRAINER AUXILIARY 2 STEAM TRAP STEAM Figure 5 Air Space Heating 48 VAT PASTEURIZATION BATCH PASTEURIZER OPERATING STANDARDS 1 All product components must be added to the batch prior to beginning the pasteurization process This includes any liquid sugar and sweeteners water milk powders and all other dairy products flavorings stabilizers cocoa products emulsifiers and vitamins There are certain flavoring ingredients that may be added after pasteurization These include flavoring ingredients having an of 0 85 or less high acid content dry sugars fruits and roasted nuts safe and suitable bacterial culture organisms and flavorings containing a high alcohol content Fruits and vegetables may be added to cultured products having a pH of 4 7 or less Such ingredients addition shall be done in a sanitary manner and the ingredients must be of a safe and wholesome quality 2 Pasteurization must be performed in equipment which is properly designed and operated and which insures that every particle of product will be held continuously for the minimum time and temperature Vats should be designed so that product can be heated to pasteurization temperatures in as short a time as practicable In no
108. diversion temperature and time scale divisions of not more than 15 minutes b Temperature accuracy within 1 F at set temperature plus or minus 5 F c Chart speed circular charts not more than 12 hours to make one revolution strip charts may show a continuous 24 hour recording d Frequency pen records the position of the flow diversion device forward or diverted flow on the outer edge of the chart Both the frequency pen and the temperature recording pen must track in the reference arc inscribed on the STLR case e Thermometric response 5 seconds or less to change 12 F 63 of a 19 degree span that includes the cut in point temperature 88 Basic HTST Pasteurization COMMANDER 1950 Pasteurizer Recorder and Recorder Controller S T L R amp H T S T Dedicated Pasteurizer Recorder Controller designed to meet requirements of the pasteurization processes NH High clarity digital displays continuous indication of hot product divert temperature Compliance Review meets PMO requirements Pasteurizer status indicator LED indication to show forward or diverted flow True time event pen position event records divert and forward flow plus optional CIP clean in process and secondary divert Up to eight diversion set points local or remote selection of hot product divert temperature settings Hot product pen calibrati
109. e a second reference mark at the pen point position on the chart 4 Determine the distance between the two reference marks and compare the distance with the time scale divisions on the record chart at the same temperature Use of an engineering type divider will greatly increase the accuracey of this measurement 5 For electric clocks remove face plate compare cycle specification on face plate with the current cycle utilized 6 Enter finding on chart and initial Record results Reseal regulatory controls as necessary Corrective Action If recorded time is incorrect the clock should be adj usted or repaired 242 PASTEURIZATION TESTING PROCEDURES TEST 4 RECORDING THERMOMETERS CHECK AGAINST INDICATING THERMOMETERS Reference Item 16 Application To all recording and recording controller thermometers used to record milk temperatures during pasteurization or aseptic processing Frequency At least once each 3 months by regulatory agency and daily by the plant or pasteurizer aseptic processor operator Criteria Recording thermometer shall not read higher than corresponding indicating thermometer Apparatus No supplementary materials required Method This test requires only that the reading of the recording thermometer be compared with that of the indicating thermometer at a time when both are exposed to a stabilized pasteurization or aseptic processing temperature Procedure 1 While the indicati
110. e at speeds from 4500 5500 rpm During this centrifugation process the heaver skim portion is forced to the outside and out one exit the skim line and the lighter cream moves inward toward the center and exits through a separate cream line WORM GEAR 4 CREAM DISCHARGE 12 BOTTOM BEARING FRAME 6 SKIM DISCHARGE There two types of ne 9 eparators presently in use in the milk processing industry These are a earlier style manually cleaned smaller capacity units and b the larger capacity CIP cleanable automatically de sludging higher efficiency units 136 HTST Auxiliary Equipment 3 The regulatory concerns for clarifiers and both types of separators are essentially identical The importance of evaluating separators in HTST systems are for the following reasons a They are highly efficient pumps or flow promoters and b They alter the flow of product through removal from the system by removing a portion of the higher fat product Separators located on the raw side of the pasteurizer must be located prior to the timing pump and must be automatically valved out of the system during periods of loss of power or shut down or when the FDD control panel selector switch is moved to the INSPECT position Remember that cream separated on the raw side must be immediately cooled and re pasteurized at minimum product standard temperatures prior to final packaging If the raw cream is processed at temperatures
111. e functions of the recorder controller 129 HOMOGENIZERS AND SEPARATORS A Homogenizers 1a 1 Mitre THEORY OF HOMOGENIZATION CHERRY BURRELL e HOMOGENIZING VALVE PLUG AND SEAT WITH REPLACEABLE VALVE CAPS CHEREY BURRELL Figure 30 THEORY OF HOMOGENIZATION CHERRY BURRELL HOMOGENIZING VALVE PLUG AND SEAT Figure 29 WITH REPLACEABLE VALVE CAPS Two Stage Homogenizer CHERRY BURRELL Figure 29 Two Stage Homogenizer 130 HTST Auxiliary Equipment 1 Definition Homogenization is the process of reducing the fat globule Homogenizer Operation size to such an extent that after 48 hours of storage no visible separation will occur The fat content also must not differ by more than 10 throughout the product This process is accomplished by forcing whole milk through small openings at extremely high pressures The homogenizer is a piston type pump utilizing usually three or five pistons driven by a crankshaft The sanitary stainless steel head contains the suction and discharge valves and the homogenizing valve or valves the orifice type of homogenization system the pistons force product through a small orifice or tightly woven stainless steel valve This is accomplished under high pressure which sheers the fat globules into minute particles Fat globules are squeezed through a valve under pressure which elongates the globules and accelerates their movement This helps attain a uniform produ
112. e names equipment photographs is for training and educational purposes only and does not constitute endorsement by the U S Department of Heath and Human Services Public Health Service Food and Drug Administration EEE ERICK EERE OK 58 Basic HTST Pasteurization PURPOSE HTST PASTEURIZATION BASIC DESIGN FUNCTION AND OPERATION To understand the principles and public health reasons for the HTST process This section reviews the basic design function and operation of the HTST system as relative to product flows and how it influences the time temperature pressure relationships within the system OB ECTIVES Following the completion of this instructional unit the participant should be able to Ke FollOw the basic flow sequence in an HTST system and give the critical control point connected with each major component List and understand the function and installation of the basic components of an HTST system and how they interrelate to the time temperature pressure requirements GIVe the public health reasoning for each of the requirements relative to the time temperature pressure concerns 59 HTST CRITICAL CONTROL POINTS INDICATING THERMOMETER ACCURACY SCALE RECORDER CONTROLLER ACCURACY DIVERSION SET POINT SEAL SENSOR LOCATION FUNCTION OPERATION CHART IN COMPLIANCE TIMING METERING PUMP LOCATION SEAL IN PLACE HOLDING TUBE PROPER S
113. e of the recording chart that records the position of the flow diversion device in a continuous flow pasteurization system This pen on a meter based system only records the flow diversion device position that has been electronically signaled by the flow recorder controller HEAT EXCHANGER Equipment designed to effect heat transfer between two or more mediums plate type triple tubes etc 339 HOLDING TUBE The section of piping in continuous flow pasteurizers of sufficient length to provide the minimum legal residence time for heated milk HOT WATER TEMPERATURE CONTROLLER A system which controls the temperature of the heating medium by regulating mixture of steam and water that circulates through the heating section of the press Transducer An instrument used in a meter based system that converts 4 20ma current signal to an air signal usually 15 30 psi which drives the flow recorder pen kPa Metric measurement equivalency kilograms of pounds per square inch Conversion factor is 0 1449 divided by psi kPa ie 1 psi 6 9 kPa LAMINAR FLOW The movement of high viscosity products through a pipe in concentric layers where the fastest particle may move at twice the speed of the average particle METERING PUMP See Timing Pump METER BASED SYSTEM The term used for those pasteurization systems employing the use of approved components of a magnetic flow control system to replace other conventional timing pumps in
114. e of the regenerator is protected from falling within 6 9 kPa 1 psi of the pressures in the raw side of the regenerator at all times including during shut down A relief valve and line on the pasteurized side of the FDD can meet this criterion if a After the relief valve and before the entrance to the pasteurized side of a regenerator all product rises at least 30 5 centimeters 12 inches higher than the highest raw milk in the system and is open to the atmosphere at that 115 point or b After exiting the pasteurized regenerator and before the pressure relief valve all product must rise at least 30 5 centimeters 12 inches higher than the highest raw milk in the system and be open to the atmosphere at that point or c The pressure relief valve is spring loaded and plumbed so that it cannot be opened or forced open in any mode Product CIP or Inspect without the assistance of pressure from the liquid flowing through the system In this case a leaking pressure relief valve can cause an unacceptable loss of pressure in the pasteurized side of the regenerator during a shut down and is considered a violation of Item 16p D PASTEURIZERS AND ASEPTIC PROCESSING SYSTEMS EMPLOYING REGENERATIVE HEATING of this Ordinance 116 Basic HTST Pasteurization LAMINAR FLOW When milk and milk products flow through the holding tube of a high temperature short time pasteurizer flow rates vary within the tu
115. e was also required between the booster pump and the raw regenerator Few if any of these type controls exist in milk plants today 3 Regenerator by pass lines These configurations are commonly used to aid during start up of modern high capacity HTST systems Their purpose is to allow the pasteurized side of the milk to milk regenerator to become pressurized while in forward flow which allows the booster pump to be energized These lines and the associated valves allow cold raw product from the balance tank to by pass the raw regenerator and feed directly to the timing pump Often when the homogenizer is used as the timing pump a centrifugal stuffing pump will feed the inlet side of the homogenizer The by pass line valves may be automatically or manually controlled This line is not used when the booster pump is in operation The by pass line and valves must be designed installed and operated to prevent product from being trapped in the dead ended blocked line for extended periods of time This may be achieved by having the line and valve close coupled or by having the valve designed to permit a small amount of product to flow through the line during normal product runs in forward flow Other effective systems may also be used 147 Close coupled booster pump bypass booster at left stuffing pump at right When an automatic back pressure control device is installed prior to the vacuum breaker it must be installed in a mann
116. e water air or electrically operated and must be designed so as to cut off the flow of water into the vacuum pan in the event of power failure 7 When culinary steam is introduced directly into the product automatic means shall be provided to maintain a proper temperature differential between incoming and outgoing product to preclude product dilution and to assure original product composition Such means may include An automatic ratio controller which a Senses the temperature of the product at the outlet of the flow diversion device prior to the addition of culinary steam and either in the vacuum chamber or at its exit This will depend upon the most effective point to measure the results of evaporative cooling and 164 HTST Auxiliary Equipment b automatically adjusts the operating vacuum in the vacuum chamber so as to assure the removal by evaporative cooling of all water added in the form of steam or any other system which will automatically preclude adulteration The optimum temperature differential between the incoming and outgoing product shall be determined for each HTST and normal raw milk supply by means of a Majonnier or substantially equivalent total solids determination by trail and error Such temperature differential shall be set on the ratio controller Ideally the product should exit the vacuum chamber at the same temperature of the product entering the chamber less any radiant temperature
117. easuring the time required for the reading of the thermometer being tested to increase 7 C 12 F through a specified temperature range temperature range must include pasteurization temperature The tempera ture used in the water bath will depend upon the scale range of the thermometer to be tested See chart on following page for recommended water bath temperatures Note This test is temporarily suspended for indicating thermometers used on UP and UHT systems until research demonstrates effective and safe alternative methods See M a 81 J une 20 1993 or section AND Chapter entitled PROCESS DESIGN CRITERIA CHAPTER VI STEAM AND INFUSION 262 PASTEURIZATION TESTING PROCEDURES Procedure 1 Immerse indicating thermometer in water bath heated to a temperature at least 11 C 19 F higher than minimum scale reading on indicating thermometer The bath temperature should be 4 C 7 F higher than maximum required pasteurization temperature for which thermometer is used 2 Immerse indicating thermometer in bucket of cold water for several seconds to cool it Note Continuous agitation of water baths during the performance of steps 3 4 and 5 is required Elapsed time between end of step 1 and beginning of step 3 should not exceed 15 seconds so hot water bath does not cool significantly 3 Insert indicating thermometer in hot water to proper bulb sensor immersion depth 4 Start stopwatch w
118. ed 2 Start the stopwatch when the flow diversion device moves to the diverted position 258 PASTEURIZATION TESTING PROCEDURES 3 Stop the stopwatch when the flow diversion device moves to the forward position for its initial cycle in the CIP mode The booster pump and other flow promoting devices separators and stuffer pumps may start at this time b Record results for the office record c Install and seal enclosure over the time delay relay Corrective Action If the flow diversion device does not remain in the diverted position for at least 10 minutes after the mode switch is moved from process product to CIP increase the set point on the time delay relay and repeat this test procedure If the booster pump runs at any time during the 10 minute delay the booster pump wiring is in need of repair 5 9 Leak Detect Valve Flush Time Delay Application The minimum one second delay applies to HTST systems in which space between the divert and leak detect valves are not self draining in the diverted flow position IMPORTANT The five second maximum flush delay does not apply to systems that do not have a restrictor in the divert line or to meter based timing systems Criteria The piping joining the divert and leak detect valve will be flushed for at least one second and not more than five seconds after the divert valve moves to the forward flow position and before the detect valve moves to the forward postion App
119. ed time temperature pressure relationships will be repeatedly stressed Methods of assuring the minimum standards will be emphasized and probably more importantly for this course the acceptable and legal requirements and recommended techniques for testing of legal pasteurizers will be emphasized This course manual in subdivided into the three basic types of pasteurization vat or batch type high temperature short time and a short section on steam injection pasteurization In HTST pasteurization chapters are also devoted to the use of auxiliary equipment and associated required controls There is also a section on magnetic flow meters or meter based systems that will provide the participant with the current requirements for their installation and testing The manual has been supplemented with various drawings graphics photos and product flow schematics for the student s reference As more and higher quality milk has become available questionable and often inferior supplies have been largely eliminated Reliable information about the quality of milk products 15 readily available and the need for costly duplication of regulatory efforts has been largely eliminated The success of the National Conference of Interstate Milk Shipments has increased confidence for the work of other food related control activities The milk program which operates on the basis of promoting uniformity and reciprocity of inspection programs is curren
120. ed for steam injection must be free of non condensable gases as these may reduce residence times in the holding tube These non condensable gases are usually removed by a use of a De aeration Tank This de aerator reduces the possibility of non condensable gases collecting in the holding tube which could reduce the holding time of the product Even though short the holding tube must be properly sloped upward to meet the PMO requirements of 1 4 minimum inch per foot 2 1 cm m d Steam used for steam injection must comply with Appendix H requirements for culinary steam See Figure 51 e Systems using steam injection must have a differential pressure limit indicator and a pressure switch to ensure adequate isolation of the injection chamber Should the pressure drop below the 10 psi minimum the FDD will divert This switch must be tested and sealed by the regulatory authority CALCULATION OF HOLDING TUBE LENGTH Because of the short holding tube length the required minimum holding times must be calculated from the pumping rate rather than the salt conductivity test Holding tube lengths have been calculated as twice the length to compensate for laminar flow With steam injection processes the holding tube is adjusted since the product volume increases because of increased volumes in the holding tube With a 120 F temperature increase by steam injection a volume increase of 12 will occur in the holding tube The values in Table 1
121. ed out of the system during periods of diverted flow and loss of power or shut down and when the FDD control panel selector switch is moved to the INSPECT position This helps assure proper pressure relationships in the regenerator and prevents negative pressure on the forward flow port of the FDD Separators located on the pasteurized side are usually placed after the pasteurized regenerator for functional purposes In these cases a vacuum breaker and fail safe positive shut off valve must be installed This vacuum breaker must meet the 12 height requirement Cream from separators located in this position is legally classified as pasteurized cream and does not require re pasteurization if packaged as either a standardized product blended with other pasteurized products to formulate low fat milk etc or as a defined cream product If the separator is located between two split milk to milk regenerators on the pasteurized side a second vacuum breaker is necessary between the separator outlet and the entrance to the pasteurized regenerator This vacuum breaker serves the purpose of protecting the pasteurized regenerator in case the positive valving out system leaks or fails preventing negative pressure from being applied on the pasteurized regenerator Also during normal operation and forward flow this vacuum breaker would protect the pasteurized regenerator during the automatic separator desludging process Note The above vacuum breakers are
122. ed steam seals are required for sterility and the aseptic surge tank is equipped with 0 2 micron Pall cartridge air filters to maintain sterility 220 HHST UP AND UHT SYSTEMS Figure 61 Falling Film Dasi Steam Infusion System GENERAL INFORMATION ON STEAM INFUSION SYSTEMS 1 The pumps recirculating water through the PRE HEATER or PRE COOLER are not required to be interwired with the metering pump as described on page 110 Item 16b of the PMO since the system diverts upon improper pressures 221 2 This system has no conventional timing pump 3 The system does not require a vacuum breaker following the pasteurized regenerator section 4 The booster pump does not have to be interwired with the flow diversion valve but must operate only when the timing pump is running 5 The booster pump may not run if the FDD is not in the fully forward or fully diverted position 6 Tower water is not acceptable in the raw or pasteurized regenerator Tower water is open to airborne contaminats bird droppings rodents even toxic chemicals Tower water may be used to cool water which is subsequently used in a water to milk regenerator water but may not be used directly in the milk regenerators Since this water system is subj ected to subsequent superheating by steam the possiblity of contamination in these instances has been ruled to have a value of acceptable diminut
123. eed centrifugal pump AC drive 1 2 Magnetic flow meter AC variable frequency motor control drive on a centrifugal pump 3 4 Sanitary check valve or other suitable automatic valve Pneumatic transducer 1 Flow recorder controller with suitable alarms Suitable flow diversion device 178 METER BASED TIMING SYSTEMS BACK PRESSURE VALVE AND FLOW CONTROLLER DIVERSION DEVICE 4 by V vacuum Cy BREAKER r a 1 PASTEURIZED PRODUCT ag secret AT DETECT LINE 5 5 a EN E i COOLER REGENERATOR 1 HEATER i 4 HOLDING TUBE i I i f i a I SIGHT 3 GLASS 0 on X X die hd I ig 12 Im Ic ta I 8 n RAV MAGNE TIC DRAIN PRODUCT FLOW METER BOOSTER PUMP 1 Qe TIMING PUMP Figure 54 Meter Based System with flow control valves 1 this line shall be at least 12 inches above any raw product piping the HTST system 2 all divert leak detection and recycle lines which return to the constant level tank must break to atmosphere at lest two pipe diameters above the over flow level 3 the overflow level of the constant level tank must be lower that the bottom of the inlet of the raw regenerator 5 required if homo is greater capacity than timing pump 6 regenerator bypas
124. een 71 C and 77 C 160 F and 170 F Apparatus Pasteurizer or aseptic processor indicating thermometer previously tested against a known accurate thermometer water baths or suitable vats or containers agitator suitable means of heating water baths and ice Note When this test is performed on recorder controllers used with HHST pasteurization or aseptic processing systems operating at or above the boiling point of water an oil bath shall be substituted for the processing operating temperature water mentioned in steps 1 4 5 6 and 7 as well as the boiling water mentioned steps 2 3 and 5 The temperature of the oil bath which is used in place of the boiling water shall be above the normal operating range but below the highest temperature division on the chart Method The testing of a recording thermometer for temperature accuracy involves the determination of whether or not the temperature pen arm will return to within 0 5 C 1 F or 1 C 2 F as provided above of its previous setting after exposure to high heat and melting ice 239 Procedure 1 Adjust the recording pen to read exactly as the previously tested indicating thermometer in the temperature range for the process being used after a stabilization period of 5 minutes 2 minutes for electronic recorder controllers at a constant temperature The water bath shall be rapidly agitated throughout the stabilization period 2 Prepare one water bath by heating to
125. em may be operated without the controls and safe guards normally required during product processing For example the booster may start at this time without requiring proper regenerator pressures d Record results for the office record Install and seal enclosure over the time delay relay if necessary Corrective Action If the flow diversion device does not remain in the diverted position for at least 10 minutes after the mode seitch is moved from PRODUCT PROCESS to CIP increase the set point on the time delay and repeat the test procedure All required safe guards and controls must be functional during this entire 10 minutes If any of these required safeguards or controls are not functional during this 10 minutes adjustments or repairs are needed In HTST systems if the booster pump runs at any time during the 10 minute delay the booster pump wiring is in need of repair METER BASED SYSTEMS While operating the system on water at or above the minimum pasteurization temperature and with a flow rate below the Flow Alarm set point and above the Loss of Signal Alarm set point 1 Turn the flow diversion device mode switch to the CIP position The flow diversion device should move immediately to the diverted position and the booster pump should stop running and separators located between regenerator sections or on the pasteurized side of the system must be effectively valved out and stuffer pumps for such separators must be de energiz
126. emperature on HHST pasteurizers using direct contact heating the product pressure switch setting is determined from Table 40 Note The pressure setting shall be adjusted upward by the diffierence between local normal atmoshperic pressure and at sea level 311 TEST 14 SETTING OF CONTROL SWITCHES FOR DIFFERENTIAL PRESSURE ACROSS THE ECTOR Application To all HHST pasteurizers and aseptic processing systems using direct contact heating When testing aseptic processing systsems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in thei test Frequency Upon installation every 3 months thereafter and whenever the differential pressure controller seal is broken Criteria The pasteurizer or aseptic processor shall not operate in forward flow unless the product pressure drop across the injector is at least 7 KPA 10 psi Apparatus A sanitary pressure gauge and a pneumatic testing device described in Test 9 1 can be used for checking and adjusting the differential pressure controller Method Check the differential pressure switch and adjust it so as to prevent forward flow unless the differential pressure across the injector is at least 69 kPa 10 psi Procedure 1 Remove both pressure sensing elements from their original locations on the pasteurizer or aseptic processor 2 Install the sanitary
127. en minute time delay An example of this would be pasteurized side flavor control equipment and or separators located on the pasteurized side of the system Apparatus Stopwatch Method Determine that the set point on the time delay is equal to or greater than 10 minutes Procedure a Operate pasteurizer in forward flow with the mode switch on the flow diversion device in the PROCESS PRODUCT position using water above the cut in temperature In systems equipped with magnetic flow meter based timing Systems operate the system at a flow rate below the Flow Alarm set point and above the Loss of Signal Alarm set point b Move the mode switch on the flow diversion device to the CIP position The flow diversion device should move immediatey to the diverted position Start the stopwatch when the flow diversion device moves to the diverted position Check all controls and safeguards which are required to be in operation when the system is in PRODUCT mode and in diverted flow For 257 example in HTST systems the booster pump must stop runing Separators located between raw regenerator sections or those located on the pasteurized side of the system must be effectively valved out and stuffer pumps for such separators must be de energized Stop the stopwatch when the CIP timer times out On most systems this 15 when the flow diversion device moves to the forward position for its initial cycle inthe CIP mode At this time the syst
128. entional timing pump without a milk to milk regenerator 324 CASE STUDIES CASE 2 pasteurizer with homogenizer as timing pump with a stuffing pump and a booster pump 325 CASE STUDIES CASE 43 pasteurizer with a booster pump homogenizer as the timing pump and a raw milk separator with a stuffing pump 326 CASE STUDIES CASE 4 HTST pasteurizer with a booster pump stuffing pump and a homogenizer as the timing pump There is separator on the pasteurized side of the system and an automatic back pressure control valve One of the milk to milk regenerators is a vacuum regenerator 327 CASE STUDIES CASE 5 HTST pasteurizer with a booster pump homogenizer of equal capacity to the timing pump a separator on the raw side of the regenerator and a regenerator back pressure control valve 328 CASE STUDIES CASE 6 HTST pasteurizer with a booster pump a homogenizer of larger capacity than the timing pump a separator on raw side a stuffer pump a meter based timing system with AC variable speed drive 329 CASE STUDIES CASE 7 HTST pasteurizer with a booster pump a meter based timing system a separator on the pasteurized side and a flow control valve 330 CASE STUDIES CASE 8 HTST pasteurizer with flavor control equipment and a separator on the raw side with a homogenizer as timing pump centrifugal pumps as needed CASE
129. er monitors all inputs and updates all outputs on a precise schedule at least once every second Most computers will be capable of performingthis function many times in one second 8 Computer programs must be stored in some form of read only memory or ROM and be available when the computer is turned on Tapes or discs which allow access to the public health controls of the pasteurizer are not acceptable 9 The computer program access must be sealed Any telephone modem accesses must also be sealed If the Input Output bus contains LAST STATE switches the Input Output bus must also be sealed The vendor must supply the Regulatory Official with procedures and instructions to confirm that the program currently in use by the computer is the correct program The Regulatory Official will use this test procedure to confirm that the correct program is in use during a start up and whenever the seal is broken 10 If the computer contains FORCE ON or FORCE OFF functions the computer must provide indicator lights showing the status of the FORCE ON FORCE OFF function The Vendor instructions must remind the Regulatory Official that all FORCE ON FORCE OFF functions must be cleared before the computer is sealed 11 The INPUT OUTPUT buses of the public health computer shall contain NO OPERATOR OVERRIDE SWITCHES 12 Computerized systems which provide for printing the recording chart by the computer must ensure that proper calibratio
130. er preferably after the vacuum breaker that will not interfere with the proper pressure relationship within the regenerator during periods of shut down or loss or power PRESSURE CONTROLLER ASSEMBLY CONTROL BOX PRESSURE CONTROLLER THROTTLING VA 6 53 Fi 56 PRESSURE GAUGE Figure 41 Automatic Pasteurized Regenerator Back Pressure Assembly 148 HTST Auxiliary Equipment The following picture illustrates the correct method for installation of a regenerator by pass in a HTST system showing a booster and a stuffer pump 447K indicator Flow Diversion Valve Pointer Regen Holding Tube _ Pasteurized Product Out Regenerator m7 n t Raw Product Timing Auto By Pass RAN Tank Pum Val Close Coupled Pump 500 12 1 to Timing Pump Note that the by pass valve is installed as air to close spring to open which helps assure raw regenerator drainage back to the constant level tank in case of system shut down Figure 42 Regenerator By Pass Assembly Showing Booster Pump Stuffer and By Pass Coupling 149 Combination systems The following systems are provided to show necessary placement of auxiliary equipment and the controls necessary to meet the requirements of the Ordinance t vacuum BREAKER m 1 CREAM RETURN VALVE EL DO 1 SKIM B
131. es of the stainless steel plates continues to heat the milk to a temperature exceeding the minimum pasteurization temperature 5 The hot milk now at or above legal pasteurization temperature and under pressure flows through the holding tube 61 where the transit time hold is at least 15 seconds The velocity or rate of flow of the milk through the holding tube is totally governed by the speed of the timing metering pump We could say then that the residence time of the milk in the holding tube is determined by the pumping rate of the timing pump the length of holding tube and the surface friction of the milk product 6 The milk then contacts the sensing bulbs of the indicating thermometer and the recorder controller If the milk temperature is not at or above the minimum required set point then the sub legal milk is returned back to the constant level tank via the diversion port and line of the flow diversion device 7 the milk contacts the STLR at or above the minimum set point 161 F the recorder controller signals the flow diversion device to assume the forward flow position and the milk flows through the forward flow port of the flow diversion device The milk from this point continues its flow through the system as legally pasteurized product 8 The hot pasteurized milk then passes through the milk to milk regenerator on the pasteurized side of the plates and gives up heat to the cold raw product on the opposite
132. es properly interwired with the timing pump ANY OTHER COMBINATIONS OR MODIFICATIONS WHICH ARE INSTALLED AND OPERATED IN ACCORDANCE WITH THE DETAILED PROVISIONS OF THESE PRACTICES MAY BE UTILIZED 150 HTST Auxiliary Equipment CREAM RETURN VALVE BACK PRESSURE VALVE AND CONTROLLER x VACUUM BREAKER nm a ACUUM PASTEURIZED BREAKER RE n DIVERSION DEVICE BY PASS VALVE 1 dit a 4 STLR 9 CREAM H HET LINE x 3 ES hn 73 4 33 3 gs lt Er y H Y dg LM E 5 12 1 L 1 PASTEURIZED PRODUCT 1 mT lt 1 48 1 HOL DIM 4 4 i I I L COOLER REGEN 2 HEATER i REGEN A RECIRCULATION LINE 5 SIGHT i GLASS RAV ALVE prain IN gt lt BOOSTER PUMP TIMING PUMP Figure 44 HTST with vacuum raw milk regenerators pasteurized separator between two pasteurized regenerators 151 152 HTST Auxiliary Equipment no VATER PSIB EAT 52 153 HEATER XXL ICH NUR vss oes m E vz Pa 1 40 2 1 154 HTST Auxiliary Equipment SEPARATE 139 cj HEATER Ta Dot 52 Figure 45 Separator on raw side between split regener
133. es very slightly about 1 4 inch then close the Shut Off valve 5 Using two open end wrenches unscrew the valve stem from the piston rod about 1 8 inch Slowly open the Shut Off valve again allowing the valve to assume the DIVERT position 6 Set the FDV MODE Switch to PROCESS and turn the timing pump on The TIMING PUMP OR OTHER FLOW PROMOTING DEVICES SHOULD NOT RUN 7 Repeat the above steps for the leak detect valve 8 Attach a new sealing wire to the air Shut Off Valve handles and record your results 249 DEVICE ASSEMBLY CHERRY BURRELL FDD 1 With the system temperature at sub legal divert set the FDV MODE Switch to INSPECT 2 After the valves have assumed the FORWARD FLOW position turn the air shut off valve handle 90 degrees which traps the air and retains the valve in the forward flow position 3 Set the FDV MODE Switch to PROCESS and turn on the metering pump The pump or any other flow promoting devices should not operate 4 Set the FDV MODE Switch to OFF Slowly open the actuator air ShutOOff valve until the piston rod moves very slightly about 1 4 inch then close the Sutt Off valve 5 Using two open end wrenches unscrew the valve stem from the piston rod about 1 8 inch Slowly open the Shut Off valve again allowing the valve to assume the Divert position 6 Set the FDA MODE Switch to PROCESS and turn the metering pump on The metering pump nor any other flow promoting device should not opera
134. et to the vacuum chamber is required This is especially significant during periods of diverted flow or shutdown This is accomplished by installing directly downstream from the flow diversion device and prior to entrance into the vacuum chamber an effective vacuum breaker plus an automatic fail save 160 HTST Auxiliary Equipment positive spring loaded air operated shut off valve This vacuum breaker does not have a height requirement and must be installed in the piping prior to the installation of the positive shut off valve i e flow diversion valve vacuum breaker gt positive shut off valve vacuum chamber 2 Also when vacuum equipment is located downstream from the flow diversion device means shall be provided to prevent the lowering of the pasteurized milk level in the milk to milk regenerator during periods of diverted flow or shutdown This is accomplished by the installation of an automatic check valve or positive type shut off valve as above and an effective vacuum breaker This vacuum breaker shall be installed after the positive shut off valve in the line between the outlet of the vacuum chamber and the inlet to the pasteurized regenerator This vacuum breaker must be installed so that the milk rises at least 12 inches above any raw milk in the system and at that point be open to the atmosphere i e vacuum chamber gt positive shut off valve gt vacuum breaker gt entrance to pasteurize regenerator
135. fails to stop when the flow diversion device is in the diverted flow position have the plant maintenance personnel check the wiring and correct the cause 9 3 2 BOOSTER PUMPS INTERWIRED WITH METERING PUMP Method Determine if booster pump stops when metering pump is off Procedure a Connect pasteurization pressure sensor to testing tee with the other end of the tee capped Caution if there is water in the HTST system ensure that the recorder controller probe and pasteurized pressure sensor ports are capped before the metering pump is turned on b Turn the metering pump and the booster pump c Place the recorder controller probe in hot water which is above the cut in temperature d Provide an adequate pressure differential to allow the booster pump to start e Turn off the metering pump The booster pump must stop Ensure that the pressure differential remains adequate and the flow diversion device remains in the forward flow position f Record the test results for the office record Corrective Action If the booster pump fails to stop when the metering pump is turned off have the plant maintenance personnel determine and correct the cause 279 Test 10 MILK FLOW CONTROLS MILK TEMPERATURES AT CUT IN AND CUT OUT References Item 16p B 16p E Milk flow controls shall be tested for milk temperature at cut in and cut out by one of the following applicable tests at the frequency prescribed 10 1 HTST PAST
136. flow may parallel the following BALANCE TANK lt BOOSTER PUMP gt RAW REGENERATOR Water to Milk 3 FEED PUMP gt STEAM INFUSION CHAMBER gt HOLDING TUBE gt SIZED ORRIFICE FLASH CHAMBER Vacuum chamber 3 PRODUCT REMOVAL PUMP HOMOGENIZER OR HIGH PRESSURE PUMP PASTEURIZED REGENERATOR Water to Milk COOLER FLOW DIVERSION DEVICE STORAGE gt PACKAGING THE ULTRATHERM Crepaco INFUSION SYSTEM Processing methods Raw milk is transferred from the balance tank by a booster pump to a plate regenerator which heats it to approximately 140 F The preheated product is drawn by a timing pump through a plate pre heater which further raises the temperature to about 170 F The preheated product then enters the infusion heater where steam is introduced to further heat the product to 295 F or above The residence time of product in the steam infuser is about 4 seconds under pressure A steam controller sensor is located in the product line near the bottom of the heater and another is in the middle of the holding tube A ratio controller is necessary to prevent product adulteration Following the holder the product enters the aseptic flash chamber In the flash chamber all added steam is evaporated under a controlled vacuum while removing off flavors weed and feed flavors excess vapors and non condensable gases These gases are passed through a plate vapor condenser with the aid of a vacuum pump The sterilized product exits at
137. flow rate in gallons per second by dividing the known volume by the time required to collect the known volume j Multiply this value gallons per second with the appropriate value in Table 14 to determine the required holding tube length k Holding tube lengths for direct contact heating pasteurizers with a pumping rate of 1 gallon second are specified in Table 14 304 PASTEURIZATION TESTING PROCEDURES Determine the number and tupe of fittings in the holding tube and convert these to equivalent lengths of straight pipe with the use of Table 13 Determine the total length of the holding tube by adding the equivalent lengths of the fittings to the measured lengths of straight pipe m Make sure that the holding tube slopes upward at least 6 35 millimeters 0 25 inch per foot n The holding tube shall also be protected against heat loss with insulation that 15 impervious to water if the temperature sensor is located at the beginning of the holding tube If the actual holding tube length is equivalent to or greater than the required holding tube length record the number and type of fittings the number and length of straight pipes and the holding tube configuration for the office record Re seal regulatory controls as necessary Corrective Action If the length of the holding tube is shorter that the calculated length lengthen the holding tube and repeat the above determination TEST 12 THERMAL LIMIT CONTROLLER
138. for the recirculation of pasteurized milk d Provides a reservoir for CIP cleaning purposes 3 Controls a The overflow level of the balance tank must be installed recommended at least one inch below the lowest level of raw milk in the regenerator 64 Basic HTST Pasteurization b Raw milk generally must enter the regenerator section at the bottom of the press If the system is equipped with a start up regenerator by pass line with a non restricting intervening valve then the raw milk line may enter at the top of the press Figu res 8 INTERNAL OVERFLOW Acceptable Balance Tank Designs k OR LARGER VENT d E p 2502 ____ 000 ____ LEVEL OVERFLOW TUBE 5 TO RAW MILK REGENERATOR 1 d 1 L me A TM SEE NOTES 1 AND 2 i k 2D OR LARGER d DIAMETER OF LARGEST RETURN PIPELINE D DIAMETER OF LARGEST SUPPLY PIPELINE NOTES 1 LARGEST DIMENSION OF TANK IS THAN 3 FEET z D BUT NOT LESS THAN 4 INCH 2 IF LARGEST DIMENSION OF TANK IS GREATER THAN 3 FEET L D BUT NOT LESS THAN 6 INCH 65 SIDE OVERFLOW 0008 14 gt d OR LARGER VENT SEE NOTE 2 OR LARGER A i we L 4 D Ad SECTION AA MINUS COVER kz SEE NOTE 1 gt TORAWMILK gt REGENERATOR SQUARE OR RECTANGULAR TANK d DIAMETER OF LARGEST RETURN PIPELINE D DIAMETER OF LARGEST SUFPLY PIPELINE NOTES
139. fter and whenever a process value is changed CRITERIA The process values are programmed locked with the values stated in this test and finally the locking mechanism is sealed by the regulatory official APPARATUS none METHOD The regulatory official shall lock the process values programmed into the firmware and then seal the back panel of the recorder controller The regulatory official shall also confirm that the process values once locked and sealed cannot be changed by plant personnel without breaking the seal PROCEDURE 1 After all the required tests are satisfactorily completed open the back panel of the recorder controller and move the control switch run or lock to the locked position see vendor s operation manual Close the recorder controller panel 2 Move the display prompts through the following Level positions to confirm the programmed process values and attempt to alter them see vendor s operations manual Level 2 CH Lo chart low 120 F Level 2 CH HI chart high 220 F Level 2 dEG C Celsius temperature scale selected no Level 2 FILt chart damping filter enabled no Level 2 CHrt SPed chart Speed 12 hrs Level 3 ALr H high alarm set point 220 F Level 3ALr L low alarm set point 0 5 above minimum pasteurization temperature or higher Level 3 A HYS hysteresis 1 F Level 2 ACK alarm acknowledge routing to Level 1 no Level 5 PEn 1 t CAL recording pen calibration f
140. gal installation Correctly perform the required tests for pasteurization systems by using the classroom pasteurization demonstration unit and or the HTST unit at a milk plant during the class field trip Tobe able to correctly trace product flow through pasteurization systems and explain the public health controls necessary to satisfy the time temperature pressure requirements including regulatory seals where required using the case study method 22 1765 1782 1810 1861 1864 1867 1886 1893 BACKGROUND AND HISTORY SIGNIFICANT EVENTS IN THE DEVELOPMENT OF MILK PAST EURIZAT ION THE ITALIAN NATURALIST SPALLANZANI NOTED THAT BOILING PRESERVES MEAT EXTRACTS THE SWEDISH CHEMIST SCHEELE PRESERVED VINEGAR BY BOILING APPERT USED HEAT TREATMENT TO PRESERVE FOODS CLOSED CONTAINER THE GERM THEORY WAS DEVELOPED PASTEUR REPORTED THAT HEAT APPLICATION TO WINE AND BEER PREVENTS ACID BITTER AND ROPY DEFECTS IN WINE THIS PROCESS WAS TERMED PASTEURIZATION PASTEUR APPLIES HEAT TO MILK AND REPORTS THE PROCESS POSTPONED MILK SOURING THE HEATING OF MILK BOILED IN A BOTTLE FOR INFANT FEEDING REDUCED ILLNESS AND SAVED LIVES BY ELIMINATING PATHOGENS WAS ADVOCATED BY SOXHLET GERMANY J ACOBI U S STRAUS SET UP FACILITY TO PASTEURIZE MILK FOR INFANTS THE FIRST MEDICAL COMMISSION WAS FORMED TO OVERSEE THE PRODUCTION OF CERTIFIED MILK 1920 s ENDICOTT STUDIES OCCURRED IN ENDICOTT NY B
141. h fail safe valves properly interwired with the timing pump 20 Regen lis the first section of a split milk to milk regenerator and Regen 2 is the subsequent second section each requires a regenerator differential pressure switch Regen 3 is a cream to milk regenerator operating at a negative pressure and requires no regenerator differential pressure switch Any other combination of modifications which are installed and operated with the above and with the detailed provisions of these practices may be utilized 181 IV REGULATORY CONSIDERATIONS NOTE Meter based systems in order to comply with the Ordinance shall be installed as complete systems as submitted and reviewed by FDA other words a complete system shall be deemed to mean a system consisting of those specific components including wiring diagrams that have been formally submitted and reviewed by the FDA The installation of other components are to be reviewed and or acceptable on an individual basis A CONSTRUCTION 1 The centrifugal pump shall be located downstream from the raw milk regenerator if a regenerator is used in the system 2 The magnetic flow meter shall be downstream from the centrifugal pump There shall be no intervening components valves or control devices in the system other than normal sanitary piping 3 Both the centrifugal pump and the magnetic flow meter and the control valve when applicable shall be located upstream from the h
142. he case of aseptic processing equipment resterilized Apparatus A constant temperature bath of water or oil and the test lamp from the pneumatic testing device described in Test 9 1 can be used to check the control sequence logic of the thermal limit controller Method The control sequence logic of the thermal limit controller is determined by monitoring the electric signal from the thermal limit controller during a series of immersions and removals of the two sensing elements from a bath heated above the cut in temperature Procedures a Heat a constant temperature water or oil bath a few degrees above the cut in temperature on the thermal limit controller Wire the test lamp in series with the signal from the thermal limit controller to the flow diversion device some processors have time delays built into their control logic in excess of that required for public health reasons bypass these timers or account for their effect in delaying forward flow 306 PASTEURIZATION TESTING PROCEDURES b Immerse the sensing element of the flow diversion device in the bath which is above the cut in temperature The test lamp should remain unlighted i e diverted flow Leave the sensing element in the bath c Immerse the sensing element from the holding tube in the bath The test lamp should light up i e forward flow after a minimum time delay of 1 second for continuous flow pasteurizatin systems For aseptic processing sy
143. he discharge Their maximum pumping pressure may be lessened by shortening of the impeller or through the use of slower speed electric motors Figure 38 Centrifugal Pumps 141 High speed 3600 rpm motors are frequently used in clean up operations Since extended back pressures on centrifugal pumps can damage the pump motor high speed motors which can produce greater pressures are not usually used as booster pumps however two speed pumps may be used as dual purpose booster and CIP pumps In these cases an electrical interlock is used to prevent the high speed motor winding from being used during processing operations M Em HUB POCKET O RING SEAL GROOVES CAUSE TURBULENCE AND FLUSH OUT HUB POCKET CUT AWAY VIEW OF A CENTRIFUGAL PUMP TRI CLOVER Figure 39 Centrifugal Pump Interior 142 HTST Auxiliary Equipment BOOSTER PUMPS A Introduction A booster pump may be installed in continuous pasteurizer systems under certain closely controlled conditions Booster pumps serve several functions in modern HTST systems including 1 Assist the timing pump in moving raw milk from the balance tank to the raw regenerator 2 provides pressure to the homogenizer when the homogenizer serves as the timing pump 3 increases regenerator efficiency 4 reduces excessive vacuum and the associated flashing of raw milk in the regenerator and 5 must always be of the centrifugal design 143 B
144. he pens do not plant personnel or the instrument vendor would make the appropriate adjustment 12 Move display prompt to Level 4 CAL L calibrate all pens to the inner edge of the chart Observe that the recording pen and the event pen drop to the inner temperature line on the chart If the pens do not plant personnel or the instrument vendor should make the appropriate adjustment 13 Move display prompt to Level 5 t CAL then attempt to move display prompt to Level 6 If a Level 6 can be accessed on the recorder controller the instrument contains a RS 422 Communications Port which permit the process values to be changed after the instrument is sealed CORRECTIVE ACTION If the process values cannot be set as described in this test contact the vendor for repairs or further operating instructions If Level 6 can be accessed contact the vendor to remove the RS 422 Communications Port 317 TEST B Recorder Controller Calibration APPLICATION To all Taylor ER recorder controllers used in connection with continuous flow pasteurizers FREQUENCY Upon installation and every three months thereafter CRITERIA The recording thermometer shall not read higher than the corresponding indicatingthermometer Thistest must be conducted before the test for cut in and cut out temperatures APPARATUS Indicating thermometer that has been calibrated with a thermometer traceable to or certified by the National Bureau of Standards and a water o
145. he system and the booster pump inter wiring requirement may be eliminated PROVIDED the differential pressure controller is interlocked with the FDD and set and sealed to sanitize ALL PRODUCT SURFACES IN THE SYSTEM in instances of improper pressures within the milk to milk regenerator The booster pump 15 allowed to run at all times b Milk Water Milk Regenerators In these systems the product flows counter current within a plate or tubular heat exchange system with a heat exchange medium usually water used on the opposite side of the plate or in the case of tubular within the surrounding tube s The heat transfer medium is looped within the system to preheat heat precool and cool the product to accepted standards Sometimes warm vapors extracted from the vacuum flash chamber and the cooling properties of plant tower water systems are used for regeneration of the heat transfer medium 215 ASEPTIC PROCESSING SYSTEMS UHT Aseptic processing involves the application of a sufficient heat processing using commercially sterile equipment and subsequentially filled under aspetic conditions in hermetically sealed packaging The product is termed shelf stable and may be stored without refrigeration Regulations and guidelines for these processes may be found in the 21 Code of Federal Regulations Sections 108 and 113 and in th PMO Section 7 Item 16 p and in the PMO Appendix All milk aseptic operations are required to file the process
146. hen indicating thermometer reads 11 C 19 F below bath temperature 5 Stop stopwatch when indicating thermometer reads 4 C 7 F below bath temperature 6 Record thermometric response time for office record Examples On a thermometer with a range of 66 C to 80 C 150 F to 175 F used at pasteurization temperatures of 72 C and 75 C 161 F and 166 F a water bath of 78 3 C 173 F could be used 10 6 C 19 F below 78 3 C 173 F would be 68 7 154 F 3 9 C 7 F below 78 3 C 173 F would be 74 4 C 166 F Hence after immersing the thermometer which has been previously cooled place the thermometer in the 78 3 C 173 F bath the stopwatch is started when the thermometer reads 67 8 C 154 F and stopped when it reads 74 3 C 166 F NOTE The above test included the pasteurization temperature of 71 7 C 161 F and 74 4 166 If the pasteurization temperature set points had been 71 7 C 161 F AND 79 4 C 175 F it would 263 have not been possible to include both set points within a 6 7 C 12 F span With these set points the test would have to be done separately for each set point Therefore a thermometer used at pasteurization temperature of 175 F could use a water bath of 182 F and the measured time span would be 163 F to 175 F THERMOMETRIC RESPONSE TEST QUICK REFERENCE PASTEURIZATION WATER BATH TIMED 12 F SPAN TEMPERATURE TEMPERATURE 161 F 166 F 1
147. hile FDD remains in DIVERT The FDD then is under full control of the CIP system controller and no flow promoting devices used for processing may operate during the CIP cycle This applies to those systems which utilize a separate CIP pump which is installed after shut down Condition 2 Timing pump or other flow promoting devices allowed to operate during CIP Requirement A 10 minute minimum time delay when the mode switch selector is placed in the CIP position During this time period the FDD must immediately assume the DIVERT position and all product flow promoters which may induce improper pressure relationships within the milk to milk regenerator must be deactivated or effectively valved out of the system during the 10 minute time delay This includes 1 BOOSTER PUMP 2 RAW MILK SEPARATOR LOCATED BETWEEN TWO RAWSIDE REGENERATORS INCLUDES SEPARATOR STUFFER PUMP 3 PASTEURIZED MILK SEPARATORS Separators are effectively valved out of the system since separator plates will continue to spin even when power is not provided They are powerful flow promoters Following the 10 minute time delay the system in under control of the CIP program the valves may begin their cycling function and the booster and other auxiliary equipment may operate 110 Basic HTST Pasteurization Programmable Logic Controller systems for Dual Stem Flow Diversion Devices Manufacturer Custom Control Products Mb 313 3 15 91 This
148. ibed as the principal safeguard between a potentially dangerous milk supply and the consumer Methods must be dependable and equipment constructed of material and of a type that permits easy and effective cleaning Adequate precautions must be taken to detect and avert faulty operational procedures Let s now legally define the process of pasteurization PASTEURIZATION The process of heating EVERY PARTICLE of milk and milk products to the minimum required TEMPERATURE for that specific milk or milk product and holding it continuously for the minimum required TIME in equipment that is PROPERLY DESIGNED and OPERATED Pasteurization has also been described as a heat treatment or thermal process used to kill part but not all of the vegetative microorganisms present in the food This is important to remember since the D value was established on a 90 microbe deactivation This is why milk spoils under refrigeration Biology 30 BACKGROUND AND HISTORY informs us that certain bacteria are heat resistant thermophiles while others are cold resistant psychrophiles and may withstand the heat process of pasteurization Certain of these non mesophilic organisms may be introduced into the product after pasteurization and some may survive the pasteurization process No pathogens have been demonstrated to survive pasteurization in properly designed installed and operated equipment Generally we can say that pasteurization involves a
149. ic Health Reports This first milk code initiated actions by other interested states and in 1927 a uniform national Code was published which included both technical and administrative notes for satisfactory compliance This was a major milestone Now minimum pasteurization standards could be further developed and established on a uniform nationwide basis Little did they realize that 25 years later the National Conference would be established from these initial efforts Developments then flourished The first plate heat exchangers were introduced into the U S in around 1928 Earlier in 1927 the application of a higher heat process was evolving in Europe Pennsylvania in 1931 conducted studies relative to the thermal destruction of pathogens using 160 F for a 15 second hold time Only slight changes were made to the pasteurization requirements in the 1930 s The 1939 edition of the Milk Ordinance and Code although not requiring pasteurization highly recommended that cities adopt the Ordinance if permitted in their local codes 14 BACKGROUND AND HISTORY In 1950 the Bell studies suggested that the organism Coxiella burnetii which is responsible for several Q fever Query fever outbreaks in Southern California could survive the then current pasteurization requirements This is a febrile rickettsial disease producing flu like symptoms As a result the USPHS in cooperation with University of California Davis recommended increasing the m
150. icro switch and wiring are required to locate and correct the cause 5 4 DEVICE ASSEMBLY DUAL STEM DEVICE Note 1 The test procedure presented in the section is typical of tests accepted by regulatory authorities Testing details may vary for individual flow diversion device types are provided in the device operators manuals which hav been reviewed by FDA 2 The word metering pump or timing pump found in the manufacturers manuals testing section shall be interpreted to include all other flow promoting devices capable of causing flow through the holding tube Apparatus Suitable tools as required or recommended by the individual flow diversion type Method Observe function of metering pump all other flow promoting devices capable of causing flow throughthe holding tube when the flow diversion device is improperly assembled 246 PASTEURIZATION TESTING PROCEDURES Procedures a With the device in diverted flow by temperature when flow diversion device is properly assembled remove the valve actuator top clamp b Move the device to the forward flow position and disconnect the stem from actuator This may be accomplished using the INSPECT mode locate on the device control panel c Move the device to the diverted flow position This may be accomplished by moving the mode switch on the control panel to the DIVERT position Turn on the metering pump and all other flow promoting devices The metering pump or
151. imum level of conductivity A meter based timing system has some advantages over a conventional timing system in that it has few moving parts as does a positive displacement pump does not obstruct the product flow and is not affected by changes in conductivity temperature viscosity or density Flow meter systems are required to have high and low flow or loss of signal alarms The purpose of these alarms are to assure the system will assume the divert position in those cases of excessive or inadequate product flows The purpose of the low flow or loss of signal alarm is to prohibit produce false readings on the flow controller or when there is a signal interruption to the flow meter The setting of the low flow alarm should be left to the discretion of the processor This may be accomplished by the installation of a power interrupt switch located between the meter and the flow recorder controller 184 METER BASED TIMING SYSTEMS When the flow meter system is powered and at rest no flow condition the flow rate alarm event marker must show an unsatisfactory diverted flow condition and the FDD must be in the diverted flow position regardless or product temperature This loss of signal alarm is described in the testing procedures however may be evaluated by disrupting the power to the magnetic flow meter by electronic deactivation switch The signal may be disrupted at any location which simulates interruption of power i
152. in flow rate in gallons per second and multiplying this value by the proper number in Table 12 in this 296 PASTEURIZATION TESTING PROCEDURES section to obtain the required length of holding tube Holding tube lengths for HHST pasteurizers with indirect heating for a pumping rate of 1 gallon second are as follows TABLE 12 HOLDING TUBE LENGTH INCHES FOR HHST INDIRECT HEATING PASTEURIZERS ASSUMED PUMPING RATE 1 GAL SEC HOLDING TUBING SIZE INCHES SECONDS Procedures a Examine the entire system to ensure that all flow promoting equipment is operating at maximum capacity and all flow impeding equipment is so adj usted or by passed to provide the minimum of resistance to the flow This means that in line filters must be removed booster pumps must be in operation and vacuum equipment in the system must be operating at a maximum vacuum Also before the tests are begun the pasteurizer should be operated at maximum flow for a sufficient time to purge air from the system about 15 minutes and pipe connections on the suction side of the metering pump should be made tight enough to exclude the entrance of air Increase the temperature to the 297 pasteurizer cut in temperature With the pasteurizer operating with water and in forward flow adjust the metering pump to its maximum capacity preferably with a new belt and full size impellers b Determine that no flow exists in the diverted line and measure
153. inadvertent change by a locking switch which is under regulatory seal Requirements for installation of this system are 1 Must not contain a communications option would allow it to receive instructions from another computer 2 Meets wiring specifications submitted to FDA MSB 3 Chart specifications a 12 hour maximum with 15 minute divisions and 1 F maximum scale divisions b Span must include the low alarm set point plus or minus 12 c Platinum RTD fast response tip meeting thermometric lag Test 8 d Regulatory sealable at c RTD connecting cap c Configuration switch cover c Hold down screw for chart plate 4 The four additional tests required for this instrument are configuration of process parameters Instrument calibration Cut in cut out temperatures Locking and sealing of instrument and sensor 93 ANDEDON GAUGES THERMOMETERS TRANSMITTERS RECORDERS COMTROLLERS Levee Ju ex npud AV 9900 HTST Recorder Controller four color recording technology prints trends scales events and customer specific messages on a plain paper 12 chart Hot product cold product hot water and flow rate oll recorded and or controlled in a single unit all require ments for HTST HHST and UHT applications Tha new AV 9900 HTST recorder controller is spacifi ned for use in 2 continwaus pasiourizi applicati
154. ing including diverted flow and during any periods of sudden loss of power or shutdown In the basic HTST system this is accomplished by the following required methods 1 The overflow level of the balance tank must be lower than the lowest milk level within the regenerator 2 The timing pump must be located between the outlet of the raw regenerator and the beginning of the holding tube 3 No pump other than a properly designed installed and operated booster pump shall be installed between the balance tank and the raw milk inlet to the regenerator 4 The raw milk deflector plate s is drilled to allow drainage of raw milk back towards the balance tank during system shut downs resulting from loss of power 112 sic HTST Pasteurization HIST PRESSURE RELIEF VALVES 5 There is a properly installed atmospheric type sanitary vacuum breaker installed in the system This vacuum breaker must be located in the milk line following the pasteurized milk outlet from the regenerator or cooler section and this line shall be at least 12 inches above the highest raw milk in the pasteurizer system The top of the highest raw line and the bottom of the pasteurized milk line on which the vacuum breaker is installed shall be the effective measurement points Note A 2 3 foot water column will provide one 1 psi backpressure 6 No flow promoting device which can affect the pressure relationships within the regenerator may be locate
155. ing metering pump in HTST HHST and aseptic processing and packaging systems In the previously discussed conventional systems only the temperature is monitored to control the flow diversion device and the product flow remains at a constant set speed In meter based systems the flow rate of the product through the holding tube metered prior to the product entering the holding tube is also constantly monitored and controlled resulting in forward flow only when a pre set acceptable flow rate is achieved and maintained The system must be adjusted so that when the product flow exceeds a preset sealed value the flow diversion device immediately assumes the diverted flow position Also should the flow drop to a level that will not allow accurate flow rates the flow diversion valve must also assume the diverted flow position Methods of testing these parameters will be discussed in the testing section of this manual After the flow rate returns to an acceptable level a time delay is required before the flow diversion device is allowed to return to the forward flow position The purpose of this is to assure that all products in the holding tube have been held for the minimum required time s Although the initial installations were limited to use in systems without regenerators and less viscous products current systems may now be employed on all HTST systems for all milk products Except for those requirements related to the physical presence of
156. ing the holding time the velocity of the flow e g replacement of pump motor belt driver or driven pulley or decrease in the number of heat exchange plates or the capacity of the holding tube whenever a check of the capacity indicates a speedup Apparatus No supplemental materials needed Criteria Every particle of product shall be held for the minimum holding time in both forward and diverted flow positions Method Fully developed laminar flow and a temperature increase by steam injection of 67 C 120 F are assumed the temperature time standard is chosen by the processor and the required holding tube length is calculated from an ex perimental determination of pumping rate Procedures a Examine the entire system to ensure that all flow promoting equipment is operating at a maximum capacity and all flow impeding equipment is so adj usted or bypassed as to provide the minimum resistance to the flow 300 PASTEURIZATION TESTING PROCEDURES b Remove in line filters make certain booster pumps are operating and that vacuum equipment in the system is operating at maximum vacuum c Operate the pasteurizer on water at maximum flow for a sufficient time to purge the air from the system about 15 minutes and tighten pipe connections on the suction side of the metering pump to exclude entrance of air d Adjust the metering pump to its maximum capacity Determine that no flow exists in the diverted line and measu
157. inimum batch pasteurization temperature from 143 to 145 F maintaining the 30 minute minimum holding period Also those milk products with added sugar and or fat would require an additional 5 degrees heat The application of heat to milk for the purposes of preservation with the extra benefit of the protection of public health continues to develop Innovative methods are now available for processing milk at ultra high temperatures UHT with reduced holding times Pasteurization systems have become more complex Methods of concentration have evolved from the mid 1850 s G Borden s vacuum condenser to the ultramodern methods of concentration Modern systems process milk and milk products through micro membranes and multi stage evaporator calandria systems utilizing highly efficient heat recovery regeneration systems One of the latest major developments of the 1980 s in the U S has been the aseptic processing and packaging or so called sterile milk systems which can effectively provide six to nine months shelf life under non refrigerated conditions WHY ALL THE FUSS Perhaps now that we have followed the development of pasteurization 15 BACKGROUND AND HISTORY we must ask another question why Most of us have knowledge of at least the basics of the biological sciences and may have advanced degrees in biological sanitary sciences Others might also have advanced degrees in engineering public health or dairy processing a
158. ion I COUNI Line between slurry pump 2 12 inches CIES pasteurized side vacuum br the above represents one way to be in compliance it does not preclude other methods that may be reviewed and found acceptable 124 HTST Auxiliary Equipment 2 The slurry injection valve s is are of the fail safe type spring to close and air to open and are block and bleed design with a full port open to the atmosphere between the HTST isolation seat and the slurry pump when slurry is not being injected 3 The slurry piping between the slurry pump and the injection point may rise to a height that is higher than the overflow level of the slurry supply tank s but is at least 30 5 centimeters 12 inches lower than the required opening to the atmosphere on the pasteurized side 4 The slurry supply tank has an overflow that is at least twice the diameter of the largest inlet pipe or all inlet pipes are disconnected and the openings capped during operation of the slurry pump 5 There is a check valve in the flow stream of the milk line from the last regenerator typically after the separator upstream of the injection point valve 6 If the slurry contains milk and or milk products tanks used to blend and hold such slurry shall be completely emptied and cleaned after each four 4 hours of operation or less unless it shall be stored at a temperature of 7 C 45 F or less or at a temperature of 66 C 15
159. ion systems INTRODUCTION With the trend toward consolidation of dairy plants and the resultant increase in distances required for distributing the pasteurized products processors are opting for higher temperature pasteurization systems which in most cases greatly enhance keeping quality and shelf life of processed milk products The industry has expressed interest in processes that use higher temperatures 191 F and above for shortened times one second and less for the processing pasteurization of Grade A milk products This process is appropriately called HHST Higher Heat Shorter Time or Extended Shelf Life Systems Most of these systems are being used to process Ultra Pasteurized products and require normal legal flow diversion devices Also most of them operate temperatures in the 270 F to 300 F range These higher processing temperatures with shorter times produce an increase in product shelf life without significantly affecting the desirable flavors of the milk product The minimum required times and temperatures are based on the ice cream thermal death curve and computations assume full laminar flow The calculated holding times are not required to be adjusted for higher product viscosities HHST INDIRECT HEATING Systems which employ the use of heat exchangers to 192 HHST UP AND UHT SYSTEMS pasteurize milk products at temperatures between 191 F to 212 F at holding times between 1 0 second and 01 seco
160. irements of Appendix H V Criteria for the Evaluation of Computerized Systems for Grade A Public Health Controls of this Ordinance c The pressure relief valve vent opening is such that any leakage is readily visible This may be accomplished by opening the valve vent directly to the floor or by providing sanitary piping from the valve vent to the constant level tank If the later option is utilized the piping shall be properly sloped to assure drainage to the constant level tank and provide a means of leak detection such as by a properly located and installed sight glass 114 Basic HTST Pasteurization d The pasteurizer shall not be timed if the valve is leaking e If the valve is leaking during operation the system is considered in violation of Item 16p D PASTEURIZERS AND ASEPTIC PROCESSING SYSTEMS EMPLOYING REGENERATIVE HEATING of this Ordinance unless the loss of the pasteurized side regenerator pressure during a shutdown in forward flow is otherwise effectively prevented For Example In a magnetic flow meter based timing system there is a fail safe spring to close valve or check valve that must also be located between the timing pump and the holding tube This item is satisfied if the pressure relief valve is located prior to this fail safe valve or check valve Pressure relief valves are allowed to be located downstream from the Holding Tube in HTST Systems if 1 The pressures in the pasteurized sid
161. is automatically diverted and 2 The thermal limit sequence controllers will only allow forward flow following complete sanitizing of all product contact surfaces downstream from the holding tube This includes both minimum times and temperature requirements i e all the above product surfaces must be exposed to fluid at pasteurization temperature for the minimum required pasteurization time This 15 achieved in a direct steam heating system by requiring that following a temperature diversion all three sensing elements must attain pasteurization temperatures simultaneously and continuously for the required pasteurization time or a miminum of one 1 second This assures that all parts of the system have been properly heat sanitized prior to allowing the flow diversion device to move into the forward flow position Once the minimum temperature and time have been satisfied for system sanitization the two auxiliary controllers at the FDD and vacuum chamber then drop out and the primary recorder controller STLR at the end of the holding tube resumes it function as during normal processing The product temperature in the holding tube and the position of the flow diversion device frequency pen must be recorded on the main recorder controller temperature chart at the holding tube as in conventional systems Because of the cooling properties of the vacuum chamber and it s appurtenances it must have the temperature sensor lo
162. is done with the pressure switches by passed to achieve forward flow Direct heating 1 Requires that forward flow commences only after the sensors located at the holding tube the coolest portion of the vacuum chamber and the flow diversion device at the end of the system have reached the minimum cut in temperature after time delay of gt 1 second 2 If the unit has an excessive time delay this would be by passed and the pressure switches are by passed to achieve forward flow during the test HHST DIRECT STEAM HEATING 197 Some processors may elect to install equipment which adds steam directly to milk products during HHST pasteurization This method of processing requires both conventional and supplementary controls to assure a product protection The two categories of direct steam heating systems are catagorize as a steam injection and b steam infusion With injection steam is forced through a properly designed sanitary nozzle into the milk flow With infusion milk is introduced into a vessel having a steam atmosphere Vapor Removal Equipment In all systems using either injection or infusion methods large vessels are installed within the system to either remove the water in the form of vapor s following steam injection or to add the steam and simultaneously remove the vapors as in steam infusion systems These vessels are operated under adjustable vacuum atmospheres and are equipped with vapor vacuum w
163. is test Frequency Upon installation and semiannually thereafter whenever the seal on the Flow Alarm 15 broken any alteration is made affecting the holding time the velocity of the flow or the capacity of holding tube or whenever a check of the Capacity indicates a speedup Criteria When flow rate equals or exceeds the value at which the holding time was measured the Flow Alarm shall cause the flow diversion device to assume the diverted position even though temperature of the milk in the holding tube is above pasteurization or aseptic processing temperature Apparatus None Method Adjust the set point of the Flow Alarm so that flow is diverted when the flow rate equals or exceeds the value at which holding time was measured 291 Procedure a Operate the pasteurizer or aseptic processing equipment in forward flow at the flow rate at which holding time was measured using water above pasteurization or aseptic processing temperature b Adjust set point on the Flow Alarm slowly downward until the frequency pen on the Recorder indicates that flow has been diverted Note When performing this test on systems which operate above the boiling point of water assure that the balance tank resolution return system is cooling and engaged to avoid the possibility of serious burns c Observe that the flow diversion device moves to the diverted position while water passing through the holding tube remains above pasteurization or asep
164. ithdrawal piping connected to a condensing system and vacuum pump to remove these excess vapors They are termed vacuum chambers flash chambers or coolers and or vacuum pots by the industry and require certain regulatory controls which are addressed later in this chapter 198 HHST UP AND UHT SYSTEMS CONTROLS NECESSARY FOR DIRECT ADDITION OF STEAM a Complete steam condensation before the heated product enters the holding tube b Prevention of vapor formation in the holding tube to assure adequate holding time c Selection of effective controllers d Location of sensing elements for these controllers e Prevention of water adulteration of the product f Assurance of thermal logic controller sequence logic It is also important to remember that in either steam injection or steam infusion the requirement that the steam supply must be automatically controlled to shut off during periods of diverted flow or loss of power is not applicable for HHST and or UHT systems The reason for this is that immediately following any period of diverted flow conditions the entire system must be subjected to sterilization temperatures which requires steam heated water Methods and requirements for these sterilization systems are discussed later in this chapter 199 PROCESS DESIGN CRITERIA 1 STEAM INJ During steam injection the product is preheated a heat exchanger then heated to pasteurization
165. iveness No special controls are required for tower water plate exchangers used to cool water used in product water product heat exchangers 7 Steam infusion systems used for the processing of ultra pasteurized products only may use the flow rate at the exit end of the flow diversion valve to determine the holding time Aseptic systems using direct steam infusion providing shelf stable products still must use the laminar flow calculations as described earlier Product pressures in the holding tube must be monitored with a pressure limit switch as in other direct steam application systems 8 The positive shut off valve and vacuum breaker requirement between the flash chamber and the pre cooler section of the milk water milk regenerator is not required on HHST falling film type systems since improper relationships in the pre cooler will automatically result in diverted flow 9 HHST systems may use an acceptable FDA MSB reviewed digital indicating thermometer RTD type in place of the mercury in glass thermometer holding tubes These RTD s must be sealed to maintain calibration integrity Pipeline size may be a limiting factor 10 Generally these systems have not been modified for use in processing shelf stable products as in aseptic processing and packaging systems as covered in the PMO and LACF processing guidelines however this area is currently under FDA review 222 HHST UP AND UHT SYSTEMS 11 Atypical system product
166. ization c Each vat pasteurizer must be provided with an approved air space thermometer The air space thermometer must meet the same general requirements of the indicating thermometer with exception of the bulb length degree increments and accuracy requirements 44 VAT PASTEURIZATION sup RUBBER GASKET Z dans _ RUBBER GASKET em Y PYREX CASE e _ SCALE SCREWS 190 793 E200 TUBE AND SCALE of N AE seal LE E 1305 130 lii a RUBBER GASKET 2 7 E ug _ VULCABESTON WASHER INNER STEM Li AND ASBESTOS ROPE ZB E i umaro MERCURY t Figure 4 Indicating Thermometer The bottom of the bulb chamber for air space thermometers must not be less than 2 inches nor more than 3 5 inches below the underside of the top enclosure bridge or cover The bottom of the bulb must never be less than 1 inch from the top surface of the product during pasteurization The air space thermometer may be graduated in 2 degree maximum increments and must be accurate to plus or minus 1 degree F 45 VAT PASTEURIZATION d Each vat must also be equipped with a recording thermometer This thermometer must be graduated in 1 F increments between 140 F and 155 F The chart must be graduated in time scale divisions of not than 10 minutes for a maximum record of 12 hours and must be specifically designed
167. k valve may be installed in the recirculating line 5 to prevent non homogenization In this installation the homogenizer is of larger capacity than the timing pump c When the homogenizer is of smaller capacity than the timing pump as is Figure 33 then a pressure relief valve and relief line must be installed at the inlet of the homogenizer to allow product to return to the balance tank in those instances when the system supplies more product to the homogenizer than it can normally handle The pressure relief valve is installed at a pre set value and releases opens under conditions when product flows are in excess of homogenizer capacities d Homogenizers may be installed in conjunction with conventional timing pumps when it is desired to process homogenized milk and use the homogenizer as the timing pump as is Figure 34 In these systems the homogenizer by pass line 4 must be equipped either with pinned manual valves or positive fail safe air operated shut off valves This method prevents slippage by either device which could result in sub legally timed product In these systems both the homogenizer and the timing pump must be sealed at the fastest speed and both are considered as legal timing pumps 132 HTST Auxiliary Equipment i I PASTEURIZED PRODUCT H A b ied I i I I I I i E i i i i I _ RECYCLE i H DRAIN Fig 31 Homogenizer as a Non Flow Promoter 1 THIS LINE
168. kPa 10psi 200 HHST UP AND UHT SYSTEMS PRODUCT bd gla m za Ea STEAM Figure 57 Examples of Steam Injectors 201 b HOLDING TUBE PRODUCT PRESSURES Product pressures must be sufficient in the holding tube in order to condense the steam and keep the product in the liquid phase Low product pressures could allow vaporization and significantly reduced holding times In HHST systems a product pressure of 10 psi 69 kPa in the holding tube is adequate for temperatures of 191 F through 212 F The pressure switch must be interwired to divert the system if adequate pressure is not maintained Aseptic systems which operate at temperatures above 212 F must maintain holding tube product pressures of at least 69 kPa 10psi at sea level above the boiling pressure of the product at its maximum temperature in the holding tube The pressure switch must be capable of recording pressures and interwired to divert the system if proper pressure in not maintained in the holding tube See Table 40 for pressures which apply to installations operating from 212 to 300 F For installations above sea level the operating pressures are increased accordingly to the locality Table 40 Pressure Switch Settings Pressure Switch Setting PSIG AT Sea Level 141 210 230 250 270 290 Operating Temperature deg F 202 HHST UP AND UHT SYSTEMS c Culinary steam us
169. kaged products Some of the problems and reasons for these recalls were 1 Product contaminated with Listeria monocytogenes Three separate cases of U S hard and semi soft cheeses Product contained undeclared food colorings Product contaminated with unnamed bacteria Metal fragments found in packaged product Botulism potential in product pasteurized process cheese Powdered whole and low fat milk contaminated with Salmonella 8 Yogurt and shake mix contaminated with Salmonella organisms Se Noting the above we as public health professionals milk industry quality control consultants plant management and employees must evermore realize and stress the significance of assuring the proper production processing and handling of milk and milk products Pasteurization is the only public health measure which if properly applied will adequately protect against all infectious milk borne disease organisms which may have entered the milk prior to pasteurization 19 BACKGROUND AND HISTORY We cannot however assume that the pasteurization of milk will completely assure a safe product for the consumer The human factor and equipment failures can play an equally significant role in the safety and wholesomeness of any food product and even more so in milk This manual will concentrate efforts towards the principles theories and mechanics of proper pasteurization techniques System controls will be discuss
170. lighted i e diverted flow Re seal regulatory controls as necessary Corrective Action If the control sequence logic of the thermal limit controller does not follow the pattern set out in the procedures section the instrument shall be rewired to conform to this logic 309 TEST 13 SETTING OF CONTROL SWITCHES FOR PRODUCT PRESSURE IN THE HOLDING TUBE Reference Item 16p B Application To all HHST pasteurizers and aseptic processing systems which are capable of operating with product in forward flow mode with less than 518 kPa 75 psig pressure in the holding tube When testing aseptic processing systsems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in thei test Frequency Upon installation and every 3 months thereafter whenever the pressure switch seal is broken and whenever the operating temperature is changed Criteria The pasteurizer or aseptic procesor shall not operate in forward flow unless the product pressure in the holding tube is at least 69 kPa 10 psi above the boiling pressure of the product Apparatus A sanitary pressure gauge and a pneumatic testing device described in Test 9 1 can be used for checking and adjusting the pressure switch setting Method The pressure switch is checked and adjusted so as to prevent forward flow unless the product pressure in the holding tube is at least 69 k
171. lk as a method of preservation Following several illnesses in the late 1800 s thought to be typhoid outbreaks and after investigations into the so called slop dairies authorities from the New York Academy of Medicine considered the definite need for some type of preservation process to be applied to milk used by babies and the old and infirm This group met with little success since these slop dairies were being utilized for spent grain disposal from the large breweries in the New York area In these operations the milk was produced and processed in the same grossly unsanitary facilities connected with the breweries and distilleries Surprisingly before Mr Pasteur in 1857 officially reported that the lactic fermentation souring and or curdling of milk was greatly delayed by applying heat to milk Gail Borden was busy applying for a patent for the condensing of milk under vacuum in 1853 Also Massachusetts was adopting milk control programs 1856 Thus scientists around the world were theorizing that undesirable changes in food products were attributed to the presence of microorganisms in the food and that these germs could be controlled by the application of heat Pasteur along with other renowned scientists of the era such as Abraham J acobi N J Fjord and Albert Fesca made significant contributions to the equipment designs used for milk processing systems 12 BACKGROUND AND HISTORY Some of the early equipment was ver
172. loss in the chamber and appurtenances An air operated pressure switch installed in the air control line between the ratio controller and the vacuum regulator or the steam valve adjust the amount of steam into the product when the operating vacuum in the vacuum chamber is insufficient to prevent product dilution Note Steam injection infusion as applied to HHST and systems will be discussed in Chapter VI of this manual 165 CHAPTER REVIEW 1 The primary difference between a booster and stuffer pump is 2 The conditions which must be met before the booster pump may operate are 3 Homogenizers are always considered to be flow promoting devices unless a is installed between the and 4 T F HTST systems will contain either a booster pump or a stuffer pump but never both 5 T F Homogenizers when used as the metering pump may have a recirculating line if it has a one way check valve 6 The separator must be automatically valved out of the system under which conditions if installed on the a Raw side 1 2 3 b Pasteurized side 1 2 166 HTST Auxiliary Equipment 3 7 Describe the controls necessary for vacuum chambers without steam injection or infusion under the following conditions a vacuum chamber located on the raw side of the system b vacuum chamber located downstream from the flow diversion device 8 Which arm needle on the Taylor Pressure Differential Controllers 11
173. low is exceeded a 15 second time delay will be activated automatically before the valves assume the forward flow position With the Flow Controller at the same set point and equipment adjusted as in above time the filling of a 38 liter 10 gallon can or a calibrated tank with a measured volume of water using the discharge outlet with the same head pressure as in normal operation Average the time of several trials Other acceptable methods may be used Note The COMPUTED HOLDING TIME timing of a known 290 PASTEURIZATION TESTING PROCEDURES weight or volume of water and milk and computing the adjusted holding time is not required for Magnetic Flow Meter Timing based systems m Record this result for office record and reseal the controls as necessary Corrective Action When the computed holding time for milk is less than that required in forward flow the set point on the Flow Controller shall be decreased or adjustment made in the holding tube and the timing test repeated until satisfactory holding time is achieved 11 2B CONTINUOUS FLOW HOLDERS FLOW ALARM Application To all continuous flow pasteurization and aseptic processing systems using a Magnetic Flow Meter System to replace a metering pump When testing aseptic processing systems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in th
174. low position f Quickly inject 50 ml of saturated sodium chloride solution into the holder inlet g Begin the timing process either automatically or with a stopwatch when the solution first contacts the inlet probes as indicated by a movement of the indicator change in conductivity or by other automatic means h End the timing the stopwatch with the first movement of the indicator of a change conductivity or by automatic means Record results j Repeat the test six or more times until six successive results are within 0 5 seconds of each other The average of these six tests is the holding time for water in forward flow When consistent readings cannot be obtained purge the equipment check instruments and connections and check for air leakage on suction side of the pump located at the raw product supply tank six consecutive readings within 0 5 seconds cannot be achieved in forward flow the pasteurizing system is in need of repair Note The requirement for Magnetic Timing System holding time testing in the diverted flow position is no longer required NCIMS 1997 The reasoning is that in the event of a diversion because of excessive flow rate the system requires a time delay 15 seconds for milk 25 seconds for eggnog or frozen dessert mix after acceptable flow is attained before the diversion valve can assume the forward flow position If during a temperature only divert flow condition and the maximum allowable f
175. low rate below the Flow Alarm set point and above the Loss of Signal Alarm set point using water above pasteurizer cut in temperature b With the pasteurizer operating on water above the pasteurizer cut in temperature and the flow diversion valves in the forward flow position use the Flow Controller to slowly increase the flow rate until the frequency pen on the Recorder indicates a flow diversion flow cut out point The flow diversion device will also assume the diverted position Observe the reading of flow rate from the Recorder the instant flow cut out occurs as indicated by the frequency pen c With the flow diversion device diverted because of excessive flow rate and assuring the water remains above the pasteurizer cut in temperature slowly decrease flow rate until the frequency pen on the Flow Recorder indicates the start of a forward flow movement flow cut in point Because of the time delay relay described in Test E the flow diversion device will not move immediately to the forward flow position Observe the reading from the Flow Recorder the instant flow cut in occurs as indicated by the frequency pen d Reseal regulatory controls as necessary and record results for the office record 294 PASTEURIZATION TESTING PROCEDURES Corrective Action If the cut in or cut out point occurs at flow rate equal to or greater than the value at which holding time was measured adj ust the Flow Alarm to a lower set point and
176. lternate test procedure may be used 298 PASTEURIZATION TESTING PROCEDURES TABLE 13 Centerline Distances of 3 A Fittings Inches 3 A FITTING SIZE inches Designation Alternate procecure For pasteurizers of large capacity if the method of measuraing flow rate at the discharge of the pasteurizer is inconvenient the following alternate test procedure may be used 1 Remove the divert line from the raw product supply tank and turn off the product pump feeding the raw product supply tank 2 Suspend a sanitary dip stick in the raw product supply tank and operate the pasteurizer at maximum capacity 299 3 Record the time required for the water level to move between two graduations on the dip stick The volume of water is calculated from the dimensions of the raw product supply tank and the drop in water level 4 Flow rate is determined as follows Divide the volume of water removed from the raw product supply tank by the time required to remove it Corrective Action If the length of the holding tube is shorter than the calculated length reseal the metering pump at a slower maximum speed or lengthen the holding tube or both and repeat the above determination 11 4 CALCULATED HOLD FOR DIRECT HEATING Application To all HHST pasteurizers using direct contact heating Frequency When installed and semiannually thereafter whenever the seal on the speed setting is broken whenever any alteration is made affect
177. made affecting the holding time the velocity of the flow or the capacity of holding tube or whenever a check of the Capacity indicates a speedup Criteria Every particle of milk shall be held for at least a minimum holding time in the forward flow position Apparatus Electrical conductivity measuring device capable of detecting change in conductivity equipped with standard electrodes table salt sodium chloride or other suitable conductive substance and a suitable method of injecting the conductive solution a stopwatch or automatic means of determining holding times and suitable container for conductive solutions Method The holding time is determined by timing the interval for an added trace substance to pass through the holder Procedure a Examine the entire system to insure that all flow promoting equipment is operating at maximum capacity and all flow impeding equipment is so adj usted or bypassed as to provide the minimum resistance to the flow b Adjust the set point on the Flow Alarm to its highest possible setting c Adjust the set point on the Flow Controller to a flow rate estimated to yield an acceptable holding time d Install one electrode at the inlet to the holder and the other electrode to the holder outlet Close the circuit to the electrode located at the inlet to the holder 289 Operate the pasteurizer using water above pasteurization temperature with the flow diversion device in the forward f
178. moves the valve to seal off the divert line and opens the forward flow port Compressed air at the top of the diaphragm is controlled through an air activated solenoid valve This solenoid receives an electronic from the recorder controller micro switch when the preset cut in temperature is reached Loss of air pressure or electrical signal from the recorder controller causes the spring to automatically return the valve to the closed or fail safe divert position When the flow diversion device is properly assembled and in the fully diverted position the micro switch roller will be positioned in the valve diaphragm push plate groove In this position the micro switch provides power to the timing pump and the red light on the recorder controller When the flow diversion device is in the forward flow position E N the roller rides above the ACTUATING ROLLER groove and the micro switch pU energizes the green light and MICROSWITCH the frequency pen arm on the recorder controller During legal forward flow the timing d RANGE SPRING pump is energized by the recorder controller micro switch 100 Basic HTST Pasteurization If during diverted flow the diversion device is not properly assembled or seated the micro switch roller will be mis positioned out of the groove and the timing pump will not run This prohibits any sub legal milk from entering the forward flow port of the valve during divert 3 Basic Requireme
179. mputer may be provided as inputs only to other computer systems The wiring connections must be provided with isolation protection such as solenoid relays diodes or optical coupling devicesto prevent the public health Input Output bus from being driven by the other computer system 5 Onloss of power to the computer all public health controls must assume the FAIL SAFE position Most computers can be placed in standby status by either a program instruction or manual switches When the computer is in STANDBY status all public health controls must assume the FAIL SAFE position Some computers have internal diagnostic checks that are performed automatically during start up Duringthistime the computer places all outputs in default mode In this default mode all public health controls must be in the FAIL SAFE position 360 6 Some computers or programmable controllers have Input Output buses with LAST STATE switches that permit the operator to decide what state the output bus will take on power up after a shutdown or loss of power The choices are ON OFF or LAST STATE occurring when the computer lost power These LAST STATE switches must be placed in the FAIL SAFE position 7 The computer performs its tasks sequentially and for most of real time the computer outputs are locked in the ON or OFF position while waiting for the computer to come back through the cycle Consequently the computer program must be written so the comput
180. n 10 pipe diameters of straight pipe exists both upstream and downstream measured from the center of the meter 9 There shall be an automatic means to assure proper pressure relationships in the milk to milk regenerator in cases of interruption in normal operation of the system Acceptable methods are by installation of automatic fail safe valve at a location between the outlet of the raw regenerator and the holding tube This will prevent back flow of product through the system which not only overflows the balance tank but more significantly could create positive pressure in the raw milk side of the regenerator 10 There must be a sealed time delay installed which delays movement of the flow diversion device to the forward flow position following a diversion due to an excessive flow rate This time delay must delay movement of the FDD to forward flow for at least 15 seconds milk or 25 seconds egg nog or mix after the legal rate has been established 183 11 Regulatory seals must be provided in the following areas a Flow alarm excessive flow alarm set point and loss of signal alarm b Time delay 1 Delay after divert for excessive flow rate c Time delay 2 10 minute CIP B OPERATIONAL Generally we can say that a magnetic flowmeter is used ina pasteurization system to accurately measure the volume of flow rate of a wide range and viscosity of liquids The only requirement of the product is that it must have a min
181. n is maintained During chart printing the computer must not be diverted from its public health tasks for more than one second Upon returning to public 361 health control the computer shall complete at least one full cycle of its public health tasks before returning to chart printing 13 When printing a chart some systems provide status reports on the chart paper of selected Input Output conditions This is usually done by interrupting the printing of the chart and printing the Input Output conditions Such interrupts for status printing are permitted only when continuous record is recorded on the chart When an interrupt is started the time of the start of the interrupt will be printed on the chart at the beginning of the interrupt and at the end of the interrupt The time interval during which the computer is diverted from its public health control tasks for status printing SHALL NOT EXCEED ONE SECOND Upon returning to public health control the computer shall complete at least one full cycle of its public health tasks before returning to status printing 14 When the computer prints the temperature trace of temperature in the holding tube at specific intervals rather than a continuously changing line temperature readings shall be printed not less than once every FIVE seconds except that during the THERMOMETRIC RESPONSE test the temperature shall be printed or indicated fast enough that the Regulatory Official can place the temper
182. n the flow meter system and may be done at any location convenient for the equipment vendor and processor Another important point to remember is that the 15 second time delay is not required in those instances of diverted flow asa sole result of inadequate temperature Moreover it would be impossible to properly conduct the recording thermometer thermometric response test if the 15 second delay is installed to occur on both excessive flow conditions and on temperature diversions This will be addressed more thoroughly in the testing chapter of this manual Regulatory testing of this system precludes the necessity for determining water milk conversion flow rates divert flow rates and the flush time delay between the divert and leak detect valve on dual flow diversion valve systems 185 CHAPTER REVIEW 1 a What is a magnetic flow meter b The basic components of a variable speed AC drive meter based systems are P ERE E 2 T F Centrifugal pumps may be used to replace the timing pump in a magnetic flow system 3 Three seals are required in the testing procedures for magnetic flow meters What are they a b c 4 The purpose of the required automatic shut off valve downstream from the mag meter and upstream from the holding tube is 5 The purpose of the I P Transducer in a Mag Flow system is to convert to 6 In case of diversion resulting from excessive flow rates the system must have a built in of second
183. nb Pita Figure 62 Ultratherm Crepaco Infusion System 225 226 HHST UP AND UHT SYSTEMS Figure 64 TetraPak VTIS Injection System 227 122223443222123 Figure 65 Tubular STORK UHT Systems 228 STORK 8 000 A UP STREAM SYSTEM HHST UP AND UHT SYSTEMS CHAPTER REVIEW 1 Define the following a steam injection b steam infusion 2 Why is it necessary to monitor pressure in the holding tube 3 For each 30 F product temperature increase by steam addition the product volume will increase by 96 4 Using Table 1 and the information provided below calculate the holding tube length for a steam injection system operating under the following conditions Time to fill 10 gallon 28 3 sec Holding time 0 5 sec Holding tube diameter 2 5 inches 229 5 HHST systems where is the flow diversion device located and why 6 List the location of the required STLR and thermal limit controller sensors on steam injection systems 7 Explain the term Thermal Limit Controller Sequence Logic as it applies to advanced milk processing systems 8 What is the sensor location purpose and operation of the following controls a Ratio controller b Pressure Differential Controller 9 Acceptable flow rates in the DASI system is determined by what components in the system and how are they adj usted 10 Aseptic systems cannot operate with a c
184. nd are familiar with the inherent problems associated with milk and its ability to support the growth of disease producing organisms Dr Ben Freedman in his benchmark reference book for sanitarians entitled Sanitarians Handbook proclaims that Milk is the first food of human life It isthe most nutritious food known but also the most quickly perishable food as a result of bacterial action He also has written that from the period 1938 to 1950 milk was eight times more powerful in causing illness than were water borne diseases and that it is through the work of milk sanitarians and the dairy industry that milk has become one of the nations safest and most widely consumed foods However we must not leave the chicken house unguarded Milk does not exit the teat end of a lactating dairy animal in sterile form Even if extracted in a sterile manner milk would be likely to contain organisms from within the cow s udder Although varying in number the average plate count of milk drawn in this manner would vary from 10 organisms per cubic centimeter to several thousand Udder diseases known as mastitis also contribute significant numbers of bacteria including Streptococci Staphylococci Tubercle bacilli and Brucella abortus The environment can contribute other organisms such as Salmonella Escherichia coli Aerobacter micrococcus Lactobacillus and the more recently identified Listeria Yersinia and Campylobacter Actually you ca
185. nd have access points for inspection b Flow patterns Raw and pasteurized milk flow in opposite directions which enhances heat exchange c Controls Milk milk tubular heat exchangers must meet all requirements of plate heat exchangers i e pressure controls if applicable and in all cases vacuum breaker installation in HTST systems Figure 11 Tubular Heat Exchangers Flows 69 C TIMING METERING PUMP 1 Location In basic HTST systems the conventional timing pump will be the only flow promoting device in the system Timing pumps when used in systems with milk to milk regenerators must always be placed downstream from the raw regenerator This is to assure that during operation raw milk pressures in the milk to milk regenerator are relatively less than pressures on the pasteurized side of the plates Timing pumps may be speed adjustable but are always set and sealed at the fastest minimum legal pasteurization time s Some timing pumps are electronically controlled and this controller must also be under regulatory seal Timing pumps may operate at any time except when the dual stem flow diversion device mode switch is in the Inspect position or during diverted flow the flow diversion device is improperly assembled and the micro switch is not in the proper position 2 Types a Positive displacement type Positive pumps may be of several types two of which are in common usage in the continuous flow pasteurizer
186. nds are designated as indirect heating HHST pasteurizers These systems either use plate heat exchangers as in conventional units or tubular heat exchangers The tubular heat exchangers may either be of the triple tube type as previously discussed in Chapter IV or the tube in shell type which use spiral tubes inside a rigid thick wall shell 1 PLATE HEAT EXCHANGERS INDIRECT HEATING The heat exchangers on these systems may either be of the MILK TO MILK or MILK TO WATER TO MILK type regenerators Because of the high temperatures used in these systems the flow diversion device is located at the end of the cooler or final regenerator section This is necessary for the following reasons The response time for standard STLR s and diversion devices is too slow to prevent forward flow of sub legal product and b diversion at ultra high temperatures would result in severe flashing of product in the divert line Since the flow diversion device is located at the end of the system additional controls must be in place to assure sterility of the system following any condition periods of diverted flow and prior to system start up 193 Because of the short holding times and holding tube length all HHST holding times must be determined from the pumping rate rather than the salt conductivity test Laminar flow may occur in high viscosity products since the fastest particle can move at twice the speed of the average particle Therefore the
187. ng and recording thermometers are stabilized at an acceptable pasteurization or aseptic processing temperature read indicating thermometer 2 Immediately inscribe on the recording thermometer chart a line intersecting the recorded temperature arc at the pen location record on the chart the indicating thermometer temperature initial 3 Record results 243 Corrective Action If recording thermometer reads higher than indicating thermometer the pen shall be adjusted for accuracey by the operator Re sealing may be necessary on some earlier models of computer programmable STLR s TEST 5 FLOW DIVERSION DEVICE PROPER ASSEMBLY AND FUNCTION Reference Item 16 Application To all flow diversion devices used with HTST flow pasteurization with the following exceptions Parts 1 through 9 do not apply to aseptic processing systems Parts 5 and 9 apply only to flow diversion devices used with HTST pasteurizers and parts 1 to 4 and 6 to 8 apply to all flow diversion devices used with continuous flow pasteurizers Frequency Upon installation and at least once each 3 months thereafter or whenever a regulatory seal has been broken Criteria The flow diversion device shall function correctly in operating situations and in the event of malfunction or incorrect assemply shall de energize the metering pump and all other flow promoting devices capable of producing flow through the holding tube 5 1 LEAKAGE PAST VALVE SEAT S App
188. nge or may be one of the newer type electronic programmable recorder controllers which utilize electronic remote temperature sensing devices and or computer logic The illustration of the following page shows the mechanical works of the older type Taylor 352R STLR Behind the cut a way is found the Bourdon Coils the linkages of the temperature recording and event pens arms the capsular chamber and diversion setting and controlling mechanism and the micro switches The cabinet half on the right is the hot water controller or set and contains no controls of public health significance hopefully 77 78 Racic HTST Dactenrizatinn VAPOR THERMAL SYSTEMS This type utilizes two Bourdon coils one coil activates the recording pen arm the second coil actuates the contact assembly to initiate forward or diverted flow Both single and dual diversion controllers are available VAPOR LIQUID LIQUID SEAL SEAL UNDER 80 79 The Taylor 351R STLR showing wiring pneumatic controls and micro switches Note the split capillarys capsular chamber and diversion set screw As the temperature increases the Bourdon spring tends to unwind This moves the zero screw until the baffle contacts the nozzle The baffle thus stops the air flow through the nozzle increasing the back pressure and supplying pressure in the capsular chamber The action of the push rod of the capsular chamber places the micro switch in the normally open
189. nitary check valve for systems equipped with variable speed centrifugal timing pumps A homogenizer downstream of the timing system for example centrifugal timing pump magnetic flow meter and flow control valve or check valve must be provided with a recirculaton line Any other combination of modifications which are installed and operated with the above and with the detailed provisions of these practices may be utilized 180 METER BASED TIMING SYSTEMS SEALABLE BOX REAN RETURN SEPARATOR CONTROLLER D VACUUM BREAKER DI VER I VERSION PRODUCT DE VICE F lt SEPARATOR VACUUM BREAKER i FEED VALVE L Ro PEU PERO PASTEURIZED l REAM I I 1 CHECK VALVE OR NORHALLY CLOSED VALVE k A FC REGENERATE REGENERATOR nct Hee BY PASS VALVE EAR I RAW VALVE gt VARIABLE SPEED i i add 5 ba CENTRIFUGAL PUMP DRAIN BOOSTER PUMP 1 This Bee shol be herizonte ei 17 obeve rew product piping in the HTST system H sturrinc Gigure 56 meter based system with AC variable speed drive and Pasteurized milk separation 1 this line shall be at least 12 inches above any raw product piping in the HTST system 2 all divert leak detection and recycle lines which return to the constant level tank must break to atmosphe
190. nly and does not constitute endorsement by the U S Department of Heath and Human Services Public Health Service Food and Drug Administration K K K K K K K K K K K ok 187 188 HHST UP AND UHT SYSTEMS Chapter VII TENS Water in 189 see EERE Note The use of trade names or equipment photographs is for training and educational purposes only and does not constitute endorsement by the Food and Drug Administration 190 HHST UP AND UHT SYSTEMS DIRECT AND INDIRECT HEATED ADVANCED MILK PROCESSING SYSTEMS PURPOSE To provide applicable comprehensive information regarding the evaluation and understanding of the design operation and function of advanced milk processing systems OB ECTIVES To provide the basic criteria necessary for the evaluation of indirect and direct heated extended shelf life and shelf stable pasteurization and processing systems as they relate to applicable public health requirements 12 To describe the process design criteria and calculations necessary for the computation of holding tube lengths for advanced milk pasteurization systems _ To provide the knowledge necessary to evaluate and test the required instrumentation and controls necessary for use in advanced higher heat pasteurization systems _ To describe the public health controls necessary in 191 product water product regenerators used in modern HHST and UHT pasteurizat
191. nnot name even one pathogen that would NOT thrive readily in milk Therefore we still are not out of the water completely and must 16 BACKGROUND AND HISTORY continue to be aware of the potentials associated with handling and processing a potentially hazardous food J ust recently the FDA and CDC have received reports implicating milk products in the transmission of pathogens and responsible for human illness 1982 172 confirmed with Yersiniosis from drinking pasteurized milk in Little Rock Memphis and Greenwood MS Of these 172 10 were misdiagnosed and underwent unnecessary appendectomy operations Investigation revealed pig farmer collecting route returns and returning contaminated cases back to plant The causative was not found in the milk however was isolated from the swine empty returned cases and cultures isolated from the victims 1984 Brucellosis in humans causative factor illegal Mexican style cheese in Texas 1985 Salmonella outbreak in Chicago 16 000 culture confirmed cases 2 deaths from consumption of pasteurized milk Plant never reopened 1986 Listeria monocytogenes causative agent responsible for 146 confirmed cases of Listeriosis when a nurse at a large Los Angeles hospital reported accelerated cases of miscarriages in Hispanics There were 89 deaths Investigation that followed implicated Mexican style soft cheese processed at a small plant in the L A area Plant inspection revealed
192. nsing element and allow to cool to room temperature 265 4 Heat water bath to exactly 4 C 7 F above the cut in temperature while vigorously agitating bath to insure uniform temperature 5 Immerse recorder controller bulb in bath Continue agitation during steps 6 and 7 below 6 Start stopwatch when the recording thermometer reaches a temperature of 7 C 12 F below the cut in temperature 7 Stop stopwatch when the controller cuts in 8 Record thermometric response time for office record Re seal any regulatory seals broken during the test Corrective Action If the response time should exceed 5 seconds the recorder controller must be repaired 266 PASTEURIZATION TESTING PROCEDURES TEST 9 REGENERATOR PRESSURE CONTROLS Reference Item 16 9 1 PRESSURE SWITCHES Used to control operation of booster pumps Application To all pressure switches controlling the operations of booster pumps on HTST pasteurizer systems employing regenerators Frequency Upon installation each 3 months thereafter after any change in the booster pump or the switch circuit and or whenever the pressure switch seal is broken Criteria The pump shall not operate unless there is at least a 6 9kPa 1psi pressure differential on the pasteurized milk side of the regenerator Apparatus Sanitary pressure gauge and pneumatic testing device for checking and adjusting pressure switch settings See illustration
193. nts a Systems shall be provided to insure proper positioning of the FDD to operate only when properly assembled and then only when in the fully forward or full diverted position It must be impossible to tighten the stem packing nut so as to prevent the valve from assuming the fully diverted position within the prescribed time 1 sec Leak escape ports must be unobstructed and on the forward flow side of the flow diversion device seat The forward flow seat shall close tight enough so that any leakage past the seat will not exceed the capacity of the leak escape device The poppet valves as they are known are held in place be springs and O rings When the valve is in diverted flow the leak detectors allow milk to leak past FORWARD FLOW the sealing rings gaskets of the ie DETECTORS CLOSED valve plunger and escape to the atmosphere In forward flow the springs hold these poppets against their seat which prevents leakage a Milk pressures in excess of 20 psi Voca id may prevent their proper seating and result in leakage DIVERTED FLOW LEAK DETECTORS OPEN 101 d The length of the connecting rod shall not be adjustable Power failure or loss of air pressure shall automatically move the valve to the fail safe diverted position f The flow diversion device shall be located downstream from the holding tube Except in HHST systems g The divert line shall be self draining and shall be f
194. o result in uniform product and temperature throughout the vat Product temperatures variances must not exceed 1 F between any two points within the vat at any time during the holding period b Agitators must meet construction criteria for milk contact surfaces and be designed to be easily cleanable and or removable for manual cleaning 43 VAT PASTEURIZATION c Agitator shafts must be fitted with effective drip deflection shields to prevent contamination of the milk d Agitator shaft openings shall have a minimum diameter of one inch to allow for removal and cleaning of the agitator shaft The annular space around the agitator shaft shall be fitted with an umbrella or drip shield of sanitary design to protect YT against the entrance of contaminants a 4 Indicating and Recording Thermometers a Indicating thermometers shall be of the mercury actuated direct reading type scaled to a minimum of 0 625 of an inch with a span of not less than 25 degrees F which includes the pasteurization temperature plus or minus 5 and graduated in 1 F and accurate to within 0 5 F Provided that electronic RTD direct reading type thermometers that meet the requirements and are acceptable to FDA may be used as indicating thermometers on batch type pasteurizers b The sensing bulb of the indicating thermometer official thermometer must be designed to extend fully into the product during pasteur
195. olding tube 4 All other flow promoting devices such as booster pump stuffer pumps separators clarifiers and homogenizer as well as the centrifugal pump shall be properly interwired with the flow diversion device These flow promoters may run and produce flow only when the flow diversion device is in fully forward or fully diverted flow position when in the product run mode 5 Homogenizers and separators installed in meter based systems must otherwise follow the same requirements as previously listed for conventional systems 182 METER BASED TIMING SYSTEMS 6 There shall no product entering or leaving the system or skim from a separator or other product components between the centrifugal pump and the flow diversion device Also it is important that there shall be no flow promoting devices installed downstream from the meter based timing system 7 The magnetic flow meter shall be installed so that the product has contact with both electrodes at all times when there is flow through the system This is accomplished by mounting the flow tube of the magnetic flow meter in a vertical position with the direction of flow from the bottom to the top Also the meter must be installed to assure that the sensing probes are horizonally positioned on a within the meter which helps assure constant contact with the fluid within the piping 8 The magnetic flow meter shall be piped in such a manner that at least te
196. omit 768 350 4 Using device range travel quick release and differential pressure diff 5 a FF to DF BP should stop b FF lt psi stops BP c TP off BP off Can fill time FF 1 no leakage 2 operates freely 3 metering pump stops when improperly assembled yes no 4 lt sec 5 manual divert a b amp c parts 6 response time lt 1 sec 7 Time delays INS secCIP 5 ec 8 10 minute TD in CIP whenapplies WATER TO MILK HOLDING TIME CONVERSION METHOD VOLUME WEIGHT Time required to fill measured volume of water seconds Time required to fill identical measured volume of milk seconds Compute adjusted holding time using formula where Volume method T salt time test results Wv 1032 specific gravity of milk L032 TMw calculated holding time for milk Ww Note This testis not required for meter based systems nor for those homogenizer based timing systems with a measured holding time of gt 120 ofthe minimum required holding time Example 15 second 18 seconds 25 seconds 30 seconds ALL GEAR DRIVEN TIMING SYSTEMS REQUIRE CALCULATED HOLDING TIMES Public Health Service MILK PASTEURIZATION CONTROLS TEST REPORT Food and Drug Administration Indicating Thermometers including Air 3 months Space Temperature Accuracy Recording Thermometers 3 months Temperature Accuracy Recording Thermometers 3 months Time Accuracy TESTED T
197. on optimization of pen reading to independent thermometer Second resistance thermometer option A reference thermometer option connected to an independent sensor with additional alarm divert protection ABB Kent Taylor 89 ABB Kent Tayloc COMMANDER 1900 The complete recording and control solution for pasteurization processes FAI ELECTRONIC IMPUT STLR S Analogue type This electronic recorder controller Anderson has a dual element 1000 ohm Resistance Temperature Detector RTD This Anderson model of the STLR contains no programmable microprocessor The 3 wire signal is linearized over any of the acceptable optional charts available The dual primary RTD element supplies the recording thermal limit signal and the secondary RTD supplies the verification for that signal The standard chart in 41369 120 220 F 12 hr rotation linear 1 F divisions Optional ranges include 190 290 F and 220 320 F charts This recorder controller provides for up to 4 selecting diversion set points which are adjustable with an internally mounted dial however calibration adjustments are pre set at the factory and should only be adjusted by a trained service person The factory set diversion occurs from 0 1 F to 0 2 F above the displayed set point To raise the cut in temperature SCREW CR 15 is turned counter clockwise The cut in is factory set at about 1 5 F above cut out 90 Basic HTST P
198. on devices which have the located within the valve bonnet 14 TorF The leak detect line requires a sight glass and may or have an identifiable restrictor in the line 15 In a basic HTST system when are the two times the metering pump is not allowed to operate 122 Basic HTST Pasteurization 16 Describe the placement purpose and function of the atmospheric vacuum breaker in a basic HTST system 17 Milk is considered pasteurized when a It exits the cooler section of the press b It reaches the end of the holding tube c Regenerator pressures are maintained in the system by proper placement of the flow promoting components d It exits the forward flow port of the leak detect valve of a dual stem flow diversion device 123 Liquid Ingredient Injection Systems It has become commonplace in the dairy industry to use liquid ingredient injection systems in continuous flow pasteurization systems Milk flavoring slurries condensed products and cream or skim for standardization and similar ingredients may be injected at a point after the last regenerator and before the timing pump if all of the following conditions are met 1 The slurry injection valve or vales are closed and the slurry pump is de energized when a the FDD is in the inspect mode b the timing pump is not operating and c the temperature is below the required pasteurization temperature and the FDD is not in the fully diverted posit
199. on to the destruction of pathogens and undesirable bacteria pasteurization also extends the useful life of the product with minimal alteration of flavor and physical characteristics Milk or cream used for manufactured products such as butter cheese and ice cream are subjected to heat treatments which relates to desirable characteristics of the end product Organoleptically speaking a high temperature short time process 161 F for 15 seconds for fluid milk is preferred rather than a low temperature long time treatment 145 F for 30 minutes since HTST usually results in less nutrient destruction and fewer sensory changes For market milk pasteurization conditions and requirements are based on thermal destruction of Coxiella burnetii the rickettsia organism responsible for Q fever 27 BACKGROUND AND HISTORY THERMAL PROCESS DESIGN and PASTEURIZATION THEORY Designing a thermal process to accomplish the inactivation of spores or vegetative cells requires two pieces of information The rate of destruction of the microorganism or spores and the dependence of the rate on temperature The temperature history of the product In the canning industry the term D value the time in minutes at a given temperature necessary to reduce the population of microbes or spores by 90 is widely used D values may be calculated by using Stumbo s equation as follows
200. ons The unit combines tailsale protewiien tor the pasteurization process with the broadest range of configuration options ever available in HTST cantre package This is plished via a unique Tour color printing technology which prints on plain paper 12 100 division charts Each unit is programmable for up to 4 independent recording ranges and inpul types Each scale is color coded to ils trend pen to provide a char that is single to read even wh multiple vanablas The slandard unit provides legal Safety Thermal Lirnit Recorder STLR lunctionaity with up to 5 selectable diversion setpoints Product temperature is monitored via pur treme proven dual element 1 020 olen RTD sensor The STLA monitors sensor balance between the two elements to insure failsate operation The hot product scale tampera ture and flaw diversion valve frequency trend are printed in red When contigured for divert the activated setpoint temperature is continuously printed in green The urit can be aplionalty specified to include hot water control This variable 5 normaly displayed and controliad but not recorded For multiple divert lionis Separate hal wate setpoints can be programmed be selected automaticaly when the diversion setpoint is changed Cald praduct can be specified lor Recording CPR or Recording Controling The range for this junction 15 programma
201. onventional FDD Explain why 230 HHST UP AND UHT SYSTEMS 231 Chapter VIII ise Testing PASTEURIZATION TESTING PROCEDURES PASTEURIZATION EQUIPMENT CONTROLS AND TESTS TESTING APPARATUS SPECIFICATIONS TEST THERMOMETER Type Mercury actuated readily cleanable plain front enameled back length 305 n Scale Range At least 7 C 12 F below and 7 C 12 F above the pasteurization temperature at which the operating thermometer is used with extensions of scale on either side permitted protected against damage at 149 C 300 F Temperature Represented by Smallest Scale Division 0 1 C 0 2 F Number of Degrees per 25 millimeters Inch of Scale Not more than 4 Celsius de Accuracy Within 0 1 C 0 2 F plus or minus throughout specified scale range The accuracy shall be checked against a thermometer which has been tested by the National Bureau of Standards Bulb Corning normal or equally suitable thermometric glass Case Suitable to provide protection during transit and periods when not in use 233 GENERAL PURPOSE THERMOMETER Type Pocket type Scale Range 1 30 F to 100 C 212 F with extension on either side permitted Protected against damage at 105 C 220 F Temperature Represented by Smallest Scale Division C 2 F Accuracy Within 1 C 2 F plus or minus throughout the specified scale range Checked periodically against a known accurate thermome
202. or installation requirements of auxiliary equipment and their relationship to the time temperature and pressure influences within the HTST pasteurization system 127 CRITICAL CONTROL POINTS AUXILIARY EQUIPMENT e BOOSTER PUMP LOCATION WIRING CONTROLS SENSOR LOCATION REGEN BY PASS CLOSE COUPLED ALLOWS REGEN DRAINAGE ON SHUT DOWN 7 2 LOCATION FLOW PROMOTION BY PASS LINE SIZE AND RESTRICTIONS SEPARATOR LOCATION VALVED OUT AS REQUIRED STUFFER FEED PRODUCT PUMPS PROPERLY WIRED gt VACUUM CHAMBERS LOCATION CONTROLS IN PLACE STEAM IN COMPLIANCE 128 HTST Auxiliary Equipment INTRODUCTION A Auxiliary Equipment Various product treatments in addition to the basic HTST pasteurization can readily be incorporated into the HTST system The following are examples of some of the auxiliary equipment that may be added to these basic systems 1 Homogenizers 2 Separators and Clarifiers 3 Auxiliary raw product pumps Booster Pumps Stuffer Pumps 4 Flavor control equipment Vacuum Heat B Basic Installation Criteria When any of this equipment is added to an HTST system it must be designed a Will not reduce the holding time below the legal minimum b Will not interfere with the proper pressure relationships within the milk to milk regenerator section c Will not adversely affect the minimum required product temperature the proper operation of the flow diversion device nor th
203. orifice side spiral it is flash cooled 165 F This chamber removes steam and milk vapors from the product and the milk is partially cooled The vapors and heat that is removed from the product in the flash chamber is drawn by vacuum through a goose neck located at the top of the chamber by a vacuum pump The hot vapors are condensed in a water heat exchanger In most installations this heated water is then used in the milk water milk regenerator in the pre heating regeneration section Product exits the flash chamber through the base leg and to a product removal pump which carries it to a high pressure pump homogenizer type From the high pressure pump the product is pre cooled water to milk in a regenerator which reduces the temperature to approximately 15 This water milk pre cooler regenerator requires a differential pressure controller to maintain pasteurized product pressures at least one psi above the water pressures Digital readout pressure differential controllers are usually selected for installation in these systems The pre cooled product then is finally cooled refrigerated water or glycol regenerator cooler down to 35 45 F passes by the flow diversion device and proceeds to the aseptic surge tank prior to filling System that process aseptically packaged products have the required steam blocks sterile surge tanks etc inthe system located downstream from the product diversion valving system Identifi
204. other flow promoting devices should not run If any pump starts momentarily and then stops it may indicate improper wiring of the one second time delay as allowed 16p B 2 b Separators must be effectively valved out of the system d Reassemble the device by moving it to the forward flow position and reconnecting the stem to the actuator This may be accomplished on some dual stem valve systems by placing the mode switch in th INSPECT position Move the device to the diverted flow position and replace the actuator clamp then repeat procedure for the leak detect device assembly f Re seal regulatory controls as necessary 247 Corrective Action If any flow promoting devices fail to respond as indicated an immediate check of the device assemply and wiring is required to locate and correct the cause 248 PASTEURIZATION TESTING PROCEDURES Cherry Burrell Flow Diversion Device Models Manufactured after 1 1 83 Device Assembly Test Procedures 1 With the system temperature at sub legal divert set the FDV MODE Switch to INSPECT 2 After the valves have assummed the FORWARD FLOW position turn the air shut off valve handle 90 degrees which traps the air and retains the valve in the Forward Flow position 3 Set the FDV MODE Switch to PROCESS and turn the timing pump The timing pump should not operate 4 Set the FDV MODE Switch to OFF Slowly open the actuator air Shut Off valve until the piston rod mov
205. oxes to its maximum capacity preferably with a new belt and full size impellers Check homogenizers for seals and or gears or pulley identification c Install one electrode at the inlet to the holder and the other electrode in the holder outlet Close the circuit to the electrode located at the inlet to the holder d Operate the pasteurizer using water at pasteurization temperature with flow diversion device in forward flow position e Quickly inject 50 ml of saturated sodium chloride solution or other suitable conductant such as an adequate strength acid solution into the holder inlet f Begin the timing process automatically or with stopwatch with the first movement of the indicator of a change in conductivity or by other automatic means Open the circuit to the inlet electrode and close the circuit to the electrode at the outlet of the holder g End the timing process automatically or with a stopwatch with the first movement of the indicator of a change in conductivity h Record results l Repeat the test six or more times until six successive results are within 0 5 seconds of each other The average of these six tests is the holding time for water in forward flow When consistent readings cannot be obtained purge the equipment check instruments and connections and check for air leakage on suction side Repeat tests Should consistent readings not be obtained use the fastest time as the holding time for water
206. pasteurization or is the case of aseptic processing equipment sterilization temperature for at least pasteurization or sterilization time If the product temperature falls below the pasteurization or sterilization standard in the holding tube forward flow shall not be re achieved until the product surfaces downstream from the holding tube have been re sanitized or is the case of aseptic processing equipment resterilized Apparatus A constant temperature bath of water or oil and the test lamp from the pneumatic testing device described in Test 9 1 can be used to check the control sequence logic of the thermal limit controller Method control sequence logic of the thermal limit controller is determined by monitoring the electric signal from the thermal limit controller during a series of immersions and removals of the three sensing elements from a bath heated above the cut in temperature Procedures a Heat a water or oil bath to a constant temperature a few degrees above the cut in temperature on the thermal limit controller Wire the test lamp in series with the signal from the thermal limit controller to the flow diversion device If some processors have time delays built into their control logic in excess of that required for public health reasons bypass these timers or account for their effect in delaying forward flow Before performing this test make sure the pressure switches which must be closed to achieve forward flow
207. perature range used by the plant of 160 degrees F 9 Are any regulatory seals required on a vat pasteurizer Y N Explain 10 Provide the following vat pasteurizer thermometer criteria SPAN F grads ACCURACY Chart speed Indicating F F Recording F F F 1 rev ___hrs Air Space F F For Pasteurizers using temperatures greater than 160 F see PMO pages 217 220 Indicating F F F NA Recording F F F 1 rev ___hrs Air Space F F F NA Except that strip charts may show a continuous recording over a hour period 54 VAT PASTEURIZATION 10 List the four significant requirements for a vat pasteurizer outlet valve a b d 11 Explain the reasoning for the requirement that when pre heated product is brought into a vat for pasteurizing the filling time must be adjusted How is this added time measured Notes 55 VAT PASTEURIZATION 56 Basic HTST Pasteurization Chapter Ill VACUUM E BREAKER PASTEURIZED REGENERATOR COOLER RECORDER FLOW DIVERSION spine m CONTROLLER SENSOR HOLDING TUBE RAW DIVERT LINE REGENERATOR HEATER AM TIMING PUMP meses PASTEURIZED PRODUCT CONSTANT LEVEL TANK RAW PRODUCT Note The use of trad
208. pressure gauge of known accuracy and the pressure sensing element that is installed prior to steam injection on the pneumatic testing device Leave the other pressure sensing element open to the atmosphere but at the same height as the sensing element connected to the pneumatic testing device 312 PASTEURIZATION TESTING PROCEDURES 3 Wire the test lamp in series with the micro switch of the differential pressure controller or use the method provided by the instrument manufacturer to monitor the cut in signal 4 Apply air pressure to the sensing element and determine the pressure gauge reading at the cut in point of the differential pressure switch that will light the test lamp Determine that the differential pressure cut in on the controller is at least 69 kPa 10 psi Note this test is to assure at least a 10psi pressure loss of product at exit end of the steam injector This assures complete condensation of the steam within the injector 5 After adjustment repeat the procedure 6 When the results are satisfactory seal the instrument and record the results for the office record 313 Testing of micro processor STLR s Testing the AV 9900 HTST Recorder Controller The STLR functions the same as the existing Anderson EHT 700 as it utilizes a dual element RTD with an internal comparator to insure failsafe operation Program Run Selection All tests may be performed with the unit sealed and in the Run moe In order
209. pumps used for HTST systems Criteria The booster pump shall be wired so it cannot operate if the flow diversion device is in the diverted position or if the metering pump is not in operation Apparatus A sanitary pressure gauge and pneumatic testing device as described in Test 9 1 and water with heat source 9 3 1 BOOSTER PUMPS INTERWIRED WITH FLOW DIVERSION DEVICE Method Determine if the booster pump stops by dropping the temperature and causing flow diversion device to divert Procedures a Connect pasteurization pressure sensor to testing tee with the other end of the tee capped Caution if there is water in the HTST system ensure that the recorder controller probe and pasteurized pressure sensor ports are capped before the metering pump is turned on b Turn on the metering pump and the booster pump C Place the recorder controller probe in hot water which is above the cut in temperature d Turn on the air supply to provide adequate pressure differential to start the booster pump e Remove the recorder controller probe from the hot water f When the flow diversion device moves to the diverted flow position the booster pump must stop Ensure that the pressure differential remains adequate and the metering pump continues to operate 278 PASTEURIZATION TESTING PROCEDURES g Reseal regulatory controls as necessary and record test results for office records Corrective Action If the booster pump
210. puters require high quality clean well regulated power supplies to operate reliably and safely Spurious voltage spikes can cause unwanted changes in computer random access memory RAM Some mechanical and electrical components also deteriorate with age One solution isto have two permanent programs in the computer one in RAM and one in ROM read only memory Through a self diagnostic test these two programs could be compared 363 routinely If there were differences in the programs the computer would go into default mode Another solution would be to down load the program from ROM to RAM at every start up A third solution would be to have the computer read program directly from ROM that is unchangeable However this approach is practical only in larger volume applications such as microwave ovens For most small volume applications the ROM are field alterable such as erasable programmable read only memories EPROMS electrically erasable programmable read only memories EEPROMS and electrically alterable programmable read only memories EAPROMS EPROMS EEPROMS and EAPROMS cannot be relied upon to maintain a permanent record Something is needed to ensure that the proper program is in computer memory when the Regulatory Official seals the computer 18 Computer programs used for Public Health Controls on Grade A Pasteurizers must conform to the attached logic diagrams Minor modifications to these diagrams are permissible to
211. quirements of a vat pasteurizer 8 To list the correct operational methods of a vat pasteurizer 55 To be able to describe and perform all required regulatory tests for a vat pasteurizer p Know and be able to list the CRITICAL CONTROL POINTS of a vat pasteurizer GENERAL DISCUSSION The heating of milk in a vessel has long been one of the most effective methods of rendering a relatively organism free and hopefully pathogen free milk product The product is heated in a jacketed stainless steel vat which has been fitted with water and steam to the jacket liner thermometers to monitor and record product temperatures and some means of agitation to assure uniformity in temperature distribution Other requirements include properly designed valves time temperature requirements and methods of operation which will be discussed in this chapter 36 VAT PASTEURIZATION Generally we can say that all vat or batch type pasteurizers should conform to The 3 A Sanitary Standards for Non Coil Type Batch Pasteurizers for Milk and Milk Products Number 24 01 This standard provides guidelines for the installation approved materials finish and fabrication of vat pasteurizers Also all vat pasteurizers must comply with Item 16p A of the PMO including all operational and construction requirements 37 VAT PASTEURIZATION VAT PASTEURIZATION CRITICAL CONTROL POINTS Y TIME AND TEMPERAT URE REQUIREMENT S v NOTEM
212. r oil bath with a control system capable of maintaining a mean bath temperature of 0 5 F plus or minus METHOD The indicating thermometer and the sensing element for the recorder controller are immersed in the circulating water or oil bath The temperature reading from the recording pen is compared to that from the indicating thermometer and adjusted if necessary PROCEDURE 1 Adjust the water or oil bath to a temperature that is approximately 2 F above the diversion temperature Sufficient agitation and or circulation is needed to maintain a uniform bath temperature 2 On the Taylor ER C recorder controller move display prompts to Level 5 PEn 1 t CAL pen 1 temperature calibration 3 Immerse the indicating thermometer and the sensing element of the recorder controller to their appropriate immersion levels in the water or oil bath Allow three or four minutesfor the bath temperature to regain equilibrium 4 Record the temperatures shown on the indicating thermometer digital display on the recorder controller and the recording pen for the office record CORRECTIVE ACTION If the digital display or the recording pen both on the recorder controller read higher than the indicating thermometer adjust the calibration factor of the recording pen so that they do not read higher than the indicating thermometer Record the calibration factor for the office record TEST C Taylor ER C recorder controller Cut in and Cut out temperatures
213. r or aseptic processing system in forward flow at a flow rate below the Flow Alarm set point and above the Loss of Signal Alarm set point using water b Disrupt power to the magnetic flow meter or decrease the flow through the flow meter below the low flow alarm set point Observe that the flow diversion devise and both the safety thermal limit recorder frequency pen and the flow rate frequency pen assume the diverted flow position c Reseal regulatory controls as necessary and record results for the office record Corrective Action If the valve does not divert the pens do not move Adjustment of the Low Flow Alarm or modification or repair of control wiring is required 11 2D CONTINUOUS FLOW HOLDERS FLOW CUT IN AND CUT OUT Application To all high temperature short time pasteurizers using a Magnetic Flow Meter System to replace a metering pump 293 Frequency Upon installation and semiannually thereafter whenever seal the Flow Alarm is broken any alteration is made affecting the holding time the velocity of the flow or the capacity of holding tube or whenever a check of the Capacity indicates a speedup Criteria Forward flow occurs only when flow rates are below the Flow Alarm set point and above the Loss of Signal Alarm set point Apparatus None Method By observing the Recorder readings along with the action of the frequency pen on the Recorder Procedure a Operate pasteurizer in forward flow at a f
214. r set on left and sealing plate 83 Photo of Partlow STLR with front plate removed figure 16 84 Basic HTST Pasteurization Figure 16 Schematic Drawing of Partlow Controller J PUSH ROD ADJUSTMENT CUT IN AND CUT OUT P TEMPERATURE PEN ADJUSTMENT SCREW S SET SCREW 85 The diversion set point is altered by adjusting a small threaded push rod J which is locked into place with a set screw S This adjusting mechanism is provided with a cover plate fitted with drilled screws for regulatory sealing See illustration on previous page The sensor on the left of the recorder controller controls the water temperature in the heater section of the press through a pneumatic system Temperature of the heating medium water is set on the transparent scale located on the left side of the recorder The heated water temperature entering the heating section may be directly read on the adjacent indicating pointer c Others There are other manufacturers of recorder controllers available All use the same principals but operate in slightly different ways If these systems are encountered in the field one should consult the manufacturer s manual for operating parameters MICRO PROCESSOR TYPE STLR S On J anuary 6 1989 M b 303 was issued by the FDA s Milk Safety Branch which allowed the use of computer based programmable logic in HTST Recorder Controllers These controllers are linear ba
215. r space temperature must never be less than 5 F above the minimum legal pasteurization temperature required for the milk product contained in the vat 6 Recording charts must be used only for the length of time for which it has been designed Overlapping of information on circular charts is never acceptable and is a violation of the PMO Required information on the recording chart must be legible and meet all the requirements as spelled out in the PMO 7 The outlet valve is designed to detect and expel any leakage past the valve seat and is close coupled to prevent cold pockets of milk from accumulating in the valve or piping 8 At no time during the pasteurization cycle or following pasteurization may the outlet piping be directly attached to any line or vessel containing raw milk or any other contaminating substance 50 VAT PASTEURIZATION ASSURANCE OF HOLDING PERIODS 1 Vats must be operated so that every particle of milk is held for at least 30 minutes at or above the minimum required temperature for the specific product processed 2 When the milk product is heated to pasteurization temperature in the vat and is partially cooled in the vat before opening the outlet valve the recorder chart must show at least 30 minutes at or above the minimum pasteurization temperature 3 When the milk product is preheated to pasteurization temperature prior to entering the vat the recorder chart must show a holding time of 30 minu
216. rage holding time for water Mv average time required to deliver a measured volume of milk Ww average time required to deliver an equal volume of water 0 The computation portion of thistest is not required for meter based systems nor for those homogenizer based timing systems with a measured holding time of more than 12096of the legal holding time s for 287 example 15 185 25 sec 30sec All gear driven conventional positive displacement type impeller timing pumps based timin stems must have computed holding times as described above Corrective Action When the computed holding time for milk is less than that required either in forward flow or diverted flow the speed of the timing pump shall be reduced or adjustment made in the holding tube and the timing test repeated until satisfactory holding time is achieved Should an orifice be used to correct the holding time in diverted flow there should be no excessive pressure exerted on the underside of the valve seat of the flow diversion device Governors shall be sealed on motors that do not provide a constant speed as provided in Item 16p B 5b 288 PASTEURIZATION TESTING PROCEDURES 11 2A MAGNETIC FLOW METER SYSTEMS HOLDING TIME Application To all HTST pasteurizers with a Magnetic Flow Meter System used in lieu of a metering pump Frequency Upon installation and semiannually thereafter whenever seal the Flow Alarm is broken any alteration is
217. rators GENERAL DESCRIPTION REGENERATOR PRESSSURE CONTROLS These systems are engineered usually to preheat heat and pre cool the milk within the regenerator using temperature transfer of water to milk The water is a closed loop system is recirculated in most cases is used in both the pre heater and heater and pre cooling sections of the regenerator Within these systems very high pressures are used in the regenerators particularity on the pasteurized product side of the regenerator In HHST and aseptic methods the regenerators are protected on the product pasteurized side 195 This is accomplished using an acceptable pressure differential controller 1 The raw side sensor is located in the water loop immediately after the water pump to measure the highest water pressure prior to entering the regenerator 2 The pasteurized or aseptic product side sensor is located in the PRODUCT line after the pasteurized or aseptic product exits the regenerator which measures the lowest pasteurized product pressure Many of these systems use high pressure homogenizer pumps which can generate 2 000 to 3 000 psi which requires special high pressure type pressure differential controllers 3 The product pressure in the pasteurized milk section must be under greater pressure than the water in the raw side at all times The protection is on the pasteurized side of the system and is engineered to allow pasteurized product to leak into the heating medi
218. rature and held there continuously for at least the required sterilization times or minimum processing temperatures and times as specified on the filed process Since these systems have the FDD located downstream from the cooler section all product surfaces downstream from the holding tube must also be exposed to pasteurization temperatures following diverted flow and prior to the initial start up Therefore the sensing elements at the holding tube at the vacuum chamber coolest part and at the end of the cooling section must all reach the minimum pasteurization processing time and temperature prior to allowing forward flow of the product Diverted flow therefore must occur when any one of the following conditions are evident a Loss of product temperature at the holding tube STLR sensor 217 b Improper product heat transfer medium pressures in plate or double triple tube heat exchange systems c Improper differential pressures across the steam injectors at the holding tube a 70 kPa or 10psi pressure drop across the injector is required or d Improper pressures in the holding tube Less than 70kPa Note If all the above conditions and controls are properly installed then the requirement of a vacuum breaker at the outlet of the pasteurized regenerator the balance tank height requirement and the booster pump requirement that it may not run during diverted flow may be eliminated STEAM INFUSION SYSTEMS GENERAL FLOW
219. ratures between 191 and 212 F the pressure switch must be set at 10 psi 70kPa at sea level 213 Higher operating temperatures above 212 F require higher holding tube pressures to keep the product in the liquid phase Note Figure 40 shows the pressure switch settings for operating temperatures from 212 F up to 300 Differential pressure limit indicator This control is needed to insure adequate isolation supplementary orificing of the injection chamber across the injector The instrument must have a differential pressure switch to divert the system in case the pressure across the injectors drops to below 10 psi This is accomplished by installing one sensor prior to the steam injector and the other injector immediately after the steam injector If the 10psi differential in not maintained then the instrument will automatically divert the system Pressure relationships must be adequate to assure complete steam condensation within the steam injector This instrument and its settings must be sealed after testing 214 HHST UP AND UHT SYSTEMS Regenerator Pressure Relationships and Controls a Milk to Milk Regenerators In these systems the product flow is identical as found in conventional HTST systems with one major exception The exception is that in HHST systems processing at temperatures above 191 F 89 C the FDD is located at the end of the cooling section In these systems the vacuum breaker at the end of t
220. re at lest two pipe diameters above the over flow level 3 the overflow level of the constant level tank must be lower that the bottom of the inlet of the raw regenerator 6 regenerator bypass valves must be installed to be drainable and must prevent dead ends or be drilled A drilled check valve may be used between inlets of booster pump and timing pump Air operated valves must be normally open automatically operated and controlled to open if timing device stops 8 straight pipe per manufacturers recommendations required on both sides of the centerline of the magnetic flow meter Meter shall be located so electrodes are flooded No product can enter or leave the system between the centrifugal timing pump and the flow diversion device The flow control valves if used shall be normally closed air to open This valve may be replaced with a sanitary check valve for systems equipped with variable speed centrifugal timing pumps A homogenizer downstream of the timing system for example centrifugal timing pump magnetic flow meter and flow control valve or check valve must be provided with a recirculation line 9 homogenizer by pass valve is optional and may be normally open or normally closed with all components of MBT system downstream 19 when a separator or clarifier is an integral part of the HTST or HHST system an is located upstream of the timing pump or downstream of the flow diversion device it shall be automatically valved out of the system wit
221. re the time required to deliver a known volume of water at the discharge of the pasteurizer in forward flow Repeat the test at least twice to determine that the measurements are consistent Repeat the last step a above in diverted flow by collecting the effluent at the discharge of the divert line f Select the greatest flow rate the shortest delivery time for the known volume and calculate the flow rate in gallons per second by dividing the known volume by the time required to collect the known volume g Multiply this value gallons per second with the appropriate value in Table 14 of this paragraph to determine the required holding tube length TABLE 14 Holding Tube Length HHST Direct Heating HOLDING TUBING SIZE inches TIME seconds oo 59 0 2 94059 h Determine the number and type of fittings in the holding tube and convert these to equivalent lengths of straight pipe with the use of Table 13 Determine the total length of the holding tube by adding the equivalent lengths of the fittings to the measured lengths of straight pipe If the actual holding tube length is equivalent to or greater than the required holding tube length record a the number and type of fittings b the number and length of straight pipes and c the holding tube configuration for the office record Make sure that the holding tube slopes upward at least 6 35 millimeters 0 25 inch per foot The holding tube
222. ree of restrictions or valves unless a readily identifiable restrictor is used and are so designed that stoppage of the divert line cannot occur There shall be no valves or other obstructions in the flow divert line h This valve must be completely dissembled and manually cleaned after each use 102 Basic HTST Pasteurization Figure 22a FORWARD FLOW ED F 8 ometo 6 A 1 oum PPMT 47 Gj nun sur A WT 8 GE wo E 52841 22 M man im 1107 001 Sar m co MI VALVE BODY SUB ASSEMBLY Function Single Stem Valves 103 H FLOW DIVERSION DEVICE DUAL STEM 1 Purpose To safely and accurately control and separate raw and pasteurized product flow A dual stem flow diversion device is basically two three way valves in tandem which automatically control the direction of product flow This type valve or device was designed to be cleaned in place FIGURE 23 DUAL STEM FLOW DIVERSION DEVICE ALLOY PRODUCTS CORPS 104 Basic HTST Pasteurization H B j 6 MAK OOIE COFA now PRINCIPLES OF OPERATION ALLOY PRODUCTS CORP Row
223. repeat the test 11 2bE CONTINUOUS FLOW HOLDERS TIME DELAY RELAY Application To all high temperature short time pasteurizers using a Magnetic Flow Meter System to replace a metering pump Frequency Upon installation and semiannually thereafter whenever seal the Flow Alarm is broken any alteration is made affecting the holding time the velocity of the flow or the capacity of the holding tube or whenever a check of the capacity indicates a speedup Criteria Following a flow cut in as described in the test for flow cut in and cut out forward flow shall not occur until all product in the holding tube has been held at or above pasteurization temperature for at least the minimum holding time Apparatus Stopwatch Method Set time delay equal to or greater than the minimum holding time Procedure a Operate pasteurizer in forward flow at a flow rate below the Flow Alarm set point and above the Loss of Signal Alarm set point using water above pas teurization temperature b Using the Flow Controller increase flow rate slowly until the frequency pen on the Flow Recorder indicates a diversion movement and the flow diversion device moves to the diverted position There shall be no time delay between the movements of the frequency pen and the flow diversion device 295 c With the pasteurizer operating on water above the pasteurizer cut in temperature with the flow diversion device diverted because of excessive flow rate
224. rifice or restrictor size the location size setting and manufacturer of the pressure relief pop off valve Procedures 303 a Examine the entire system to ensure that all flow promoting equipment is operating at a maximum capacity and all flow impeding equipment is so adj usted or by passed as to provide the minimum resistance to the flow b The steam pressure in the infuser shall be raised to a level just below the pressure relief point on the pop off valve c Any back pressure valves or other variable restrictions in the holding tube shall be normally placed into the fully open position d All air bleeds to the vacuum chamber shall be closed so that the chamber will be operating under maximum vacuum e Before the tests are begun operate the pasteurizer at maximum flow for a sufficient time to purge the air from the system about 15 minutes and tighten the pipe connections on the suction side of the metering pump to exclude entrance of air f Determine that no flow exists in the diverted line and measure the time required to deliver a known volume of water at the disharge of the pasteurizer in forward flow g Repeat the test at least twice to determine that the measurements are consistent h Repeat the last step a through e above in diverted flfow by collecting the effluent at the discharge of the divert line i Select the greatest flow rate the shortest delivery time for the known volume and calculate the
225. roducer processing dairy responsible There was no case washer in the plant The bottle washer had no sanitizer The pigs were housed in the same barn with the dairy animals Five culture confirmed illnesses were confirmed in two states Samples of raw milk showed positive Yesinia Environmental swabs were taken and the organism was not found to be present in the plant environment 1995 Listeria outbreak in Ohio Suspected source was product from frozen dessert plant A follow up inspection of the plant revealed several problems with the pasteurizer problems flow diversion valve and flow promoters not operating properly and direct cross connections between raw and pasteurized lines 1998 Outbreak caused by E Coli 0157 H7 Enterohemorrhagic Escherichia 18 BACKGROUND AND HISTORY coli which manifest itself by Diarrhea often bloody abdominal cramps Contaminated Cheddar and Colby cheese curd from adding raw milk to processing vat using a common bucket Investigation found pasteurizer cut out temperature at 159 degrees F dripping condensate over cheese vat use of unpasteurized city water to push pasteurized product in lines cross connections between water and product throughout the plant and poor re working practices at a receiving plant 40 known cases of illness with 20 culture confirmed cases on record In FY93 alone there were twenty two official nationally documented FDA product recalls of dairy related processed pac
226. rs Record identity of Indicating Thermometers used in Aseptic Processing Systems Corrective Action Do not run the test if the mercury column has been split or the capillary tube is broken Broken thermometers should be returned to the factory for repair When the indicating thermometer differs from the test thermometer by more than 0 25 C 0 5 F and the airspace thermometer by more than 0 5 C 1 F the indicating thermometer should be adjusted to agree with the test thermometer Retest the thermometer after adjustment Note Electronic digital read out thermometers not meeting the above criteria shall be repaired adjusted or replaced as recommended by the applicable manufacturer 238 PASTEURIZATION TESTING PROCEDURES TEST 2 RECORDING THERMOMETERS TEMPERATURE ACCURACY Reference Item 16 Application To all recording and recorder controller thermometers used to record milk temperatures during pasteurization or aseptic processing Frequency Upon installation at least once each 3 months and whenever recording pen arm setting requires frequent adjustment when sensing element has been replaced or when a regulatory seal has been broken Criteria Within 0 5 C 1 F plus or minus in specified scale range Provided that on batch pasteurizers used solely for 30 minute pasteurization of products at temperatures above 71 C 160 F recording thermometers shall be accurate to within 1 C 2 F plus or minus betw
227. ry controls necessary to assure the proper pasteurization of milk and milk products The manual was developed over the years using the current edition of the Grade A Pasteurized Milk Ordinance PMO the current 3 A Sanitary Standards and Accepted Practices applicable Memoranda issued by the FDA s Milk Safety Branch and information gathered at various seminars and training courses Table of Contents Chapter Background and History Page 10 Chapter 11 Vat Pasteurization Page 35 Chapter 111 Basic HTST Pasteurization Page 57 Chapter IV Auxiliary Equipment Page 123 Chapter V Meter Based Systems Page 165 Chapter VI Advanced Milk Processing Systems Page 183 Chapter VII Pasteurization System Testing Page 223 Case Studies Page 309 Course Critique Page 325 Definitions Page 333 Bibliography References Page 337 Appendix Page 329 PASTEURIZATION TIME TEMPERATURE REQUIREMENTS TIME TEMP TIME TEMP TIME TEMP 1 0 SEC 191 F 0 5 SEC 194 F 30 MIN 145 15SEC 161 0 1 SEC 201 05 SEC 205 F 01 SEC 212 MILK PRODUCTS with increased viscosity added sweetener or fat content 10 or more EGG NOG 25 SEC 175 F FROZEN 30 MIN 155 F 15 SEC 180 F DESSERT MIXES Note Those pasteurized milk products that are further heated in an acceptable system to a minimum of 280 for a minimum of 2 0 seconds are to be labeled as Ultra Pasteurized 30 MIN 150 15SEC 166 F C
228. s The reason for this is 7 One of the requirements for mag flow meter installation is that they be installed downstream from the timing pump and preferably in the position 186 METER BASED TIMING SYSTEMS which helps eliminate foam and assures a contact of the sensors with the conducting fluid thus eliminating air pockets There shall be a minimum of pipe diameters on each side of the mag meter measured from the of the 8 2 inch magnetic flow meter would need a minimum of inches of uniform straight product flow piping on each side of the meter to meet the PMO requirements 9 T F lInallcases meter based systems are required to have flow control valves which function to control rate of flow through the system 10 Raw milk separators may not be located between the timing pump and the holding tube since check all that apply a X proper pressure relationships in the milk to milk regenerator could be affected b fluctuations in minimum required holding time may occur in the system c loss of temperature is probable during the separation process d stuffing pumps will exert positive pressure on the flow diversion device e raw cream is illegal according to the FD amp C federal code f product may not be added or removed after the timing system K FK K K FK K K 3K ok ok Note The use of trade names or equipment photographs is for training and educational purposes o
229. s 1 4 and 6 240 PASTEURIZATION TESTING PROCEDURES Corrective Action If the pen does not return to 0 5 1 F or 1 2 F plus or minus of indicating thermometer reading the recording thermometer should be repaired TEST 3 RECORDING THERMOMETERS TIME ACCURACY Reference Item 16 Application To all recording and recorder controller thermometers used to record time of pasteurization Frequency Upon installation and at least once each 3 months thereafter or whenever the seal of a programmable recorder controller has been broken Criteria The recorded time of pasteurization shall not exceed the true elapsed time Apparatus 1 watch graduated at intervals not to exceed 1 minute and accurate to within 5 minutes in 24 hours 2 Apair of dividers or any other suitable device for measuring short distances Method Comparison of the recorded time over a period of not less than 30 minutes with a watch of known accuracy For recorders utilizing electric clocks check cycle on face plate of clock with a known cycle observe that clock is in good operating condition 241 Procedure 1 Determine if chart is appropriate to recorder Insure that the recording is aligned with the time arc of the chart at both the center and the outside 2 Inscribe reference mark at the pen point on the recorder chart and record the time 3 At the end of a minimum of 30 minutes by the watch inscrib
230. s valves must be installed to be drainable and must prevent dead ends or be drilled A drilled check valve may be used between inlets of booster pump and timing pump Air operated valves must be normally open automatically operated and controlled to open if timing device stops 8 straight pipe per manufacturers recommendations required on both sides of the centerline of the magnetic flow meter Meter shall be located so electrodes are flooded No product can enter or leave the system between the centrifugal timing pump and the flow diversion device The flow control valves if used shall be normally closed air to open This valve may be replaced with a sanitary check valve for systems equipped with variable speed centrifugal timing pumps A homogenizer downstream of the timing system for example centrifugal timing pump magnetic flow meter and flow control valve or check valve must be provided with a recirculation line Any other combination of modifications which are installed and operated with the above and with the detailed provisions of these practices may be utilized 179 FLOW j BREAKER DIVERSION 1 DEVICE 9 r LEAK DETECT LINE 44 PASTEURIZED 1 VALVE AND PRODUCT CONTROLLER 1 E 2 T A Y COOLER REGENERATOR HEATER i 1 EX a 4 MOLDING TUBE i i Y FLOV RECORDER m SIGHT
231. sed programmable microprocessors which have the capability of recording all functions alarm settings events and other public health parameters of pasteurization by programming into mounted keys and observed digital configurations on the front of the instrument The recorder is provided with two digital displays The main display indicates the measured process variable of any of the pens specified The secondary display is used for instrument configuration and error messages 86 Basic HTST Pasteurization GENERAL REQUIREMENTS FOR ELECTRONIC RECORDER CONTROLLERS ERC S 1 The ERC must not contain communication ports which allow over riding of the public health controls from another computer 2 The chart span shall be no greater than 100 F and be a 12 hour maximum chart Most of the available charts are 10 inch circular charts with 4 1 8 calibrated width 3 The temperature sensor shall be a platinum Resistance Temperature Detector RTD fast response tip that meets Test 8 requirements 4 The ERC requires two regulatory seals one on the RTD cap and the other on the back panel of the ERC which seals the programmable microprocessor and the control switch in the locked position 5 5 are approved as a part of a control system and must use the temperature sensor approved for that system 6 The four regulatory tests required of these models of ERC s are a Programming of process values b Instrument calibration
232. sen pas teurization or aseptic processing standard Apparatus No supplemental materials needed Method The cut in and cut out temperatures are determined by observing the actual temperature in the constant temperature bath at which the two sensing elements signal for forward flow cut in and diverted flow cut out Procedures a Wire the test lamp in series with the control contacts of the sensing element holding tube Immerse this sensing element in the constant temperature bath Raise the bath temperature at a rate not exceeding 0 5 C 1 F every 30 seconds Observe the temperature reading at the cut in temperature Record the temperature for the office record b After the cut in temperature has been determined and while the bath is above the cut in temperature allow the bath to cool slowly at a rate not exceeding 282 PASTEURIZATION TESTING PROCEDURES 0 5 C 1 F per 30 seconds Observe the temperature reading on the controller when the test lamp goes out cut out temperature Determine that the cut out temperature on the thermal limit controller is equivalent to or greater than the chosen pasteurization or aseptic processing standard Corrective action Where adjustment is necessary refer to manufacturer s instructions After adjustment repeat the procedure above and when the results are satisfactory record results for the office records c Repeat the procedure for the other sensing element flow diversion
233. side of the plate In turn the pasteurized milk is partially cooled 9 The partially cooled pasteurized milk then passes through the cooling section whereby re circulated coolant water sweet water or propylene glycol is used to reduce the milk temperature to below 45 F 10 The cold pasteurized milk then exits the cooler section and rises to an elevation of at least 12 inches above any raw milk in the HTST system and is opened to the atmosphere through a sanitary vacuum breaker at that point or higher 11 From this point the pasteurized milk may travel directly to a storage or surge tank for subsequent packaging or may be returned back to the constant level tank 62 Basic HTST Pasteurization VACUUM BREAKER mm umm PASTEURIZED 1 REGENERATOR COOLER RECORDER FLOW DIN ERSION CONTROLLER DEVICE eee M S CONTROLLER SENSOR HOLDING TUBE RAW DIVERT LINE REGENERATOR HEATER WW s LAT TIMING PUMP CONSTANT LEVEL TANK RAW PRODUCT 63 Il COMPONENTS OF THE BASIC HTST SYSTEM A CONSTANT LEVEL SUPPLY TANK Balance Tank l Sanitary Design The balance tank must be of a sanitary design meet all criteria of the PMO 3 A Standards and the design dimensions of MI 87 3 2 Functions a Provides a continuous supply of milk to the HTST unit b Provides return storage for sub legal milk from the flow diversion valve c Provides a means
234. ssembled paying particular attention to the actuator mounting bolts yolk mounting bolts body clamps and the valve stem to actuator stem connection 2 Make sure the temperature sensing element of the STLR is below legal pasteurization temperature 3 Momentarily turn on the timing pump to make sure it is operating properly and then turn it off 4 Remove the valve body clamp and the uper valve body port clamp the valve Lift the valve off the lower body Turn the selector switch to the INSPECT position After atime delay the valve will switch to the forward flow position Unscrew the valve stem off the actuator stem enough to insert the gap guage between the two stems Tighten the valve stem onto the guage 5 Turn the selector switch to the PRODUCT position and observe the timing pump It should not operate nor should any flow promoting device be operable during this time 6 Remove the gap guage and reassemble the valve Ensure that the valve is properly assembled The timing pump should now operate normally in the divert position 7 Repeat procedure for remaining valve 252 PASTEURIZATION TESTING PROCEDURES 5 5 MANUAL DIVERSION when booster pump is installed in the HTST system Apparatus None Method Observe the response of the system to manual diversion Procedure a With the HTST system in operation and the flow diversion device in the forward flow position press the manual diversion
235. stems no delay is required if the filed process includes a documented sterilization period d Remove the sensing element of the flow diversion device from the bath The test lamp should remain lighted i e forward flow e Remove the holding tube sensing element from the bath The test lamp should go out immediately i e diverted flow f Re immerse the sensing element of the holding tube in the bath The test lamp should remain unlighted i e diverted flow Re seal regulatory controls as necessary Corrective Action If the control sequence logic of the thermal limit controller does not follow this pattern the instrument shall be rewired to conform to this logic 12 2 HHST PASTEURIZATION AND ASEPTIC PROCESSING SYSTEMS DIRECT HEATING Application To all HHST pasteurizers and aseptic processing systems using direct contact heating When testing aseptic processing systsems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in thei test Frequency Upon installation and every 3 months thereafter and when a regulatory seal has been broken 307 Criteria The pasteurizer or aseptic processing equipmentshall not operate in forward flow until the product surfaces downstream from the holding tube have been sanitized or in the case of aseptic processing equipment sterilized On start up surfaces shall be exposed to fluid at
236. system for controlling all functions of the dual stem flow diversion device includes electronic EEPROM pre programmed entries for the time delays and CIP functioning of the devices The controller may be used for those devices with air solenoids mounted on the valve APC on in the control panels Cherry Burrell Tri clover and G amp H The controller is fitted with a clear Plexiglas cover which is sealed to prohibit unauthorized access to the programming port and memory cards The EEPROM is supplied by the installer and cannot be permanently reprogrammed and is identified to prohibit replacement Otherwise this instrument performs the identical functions of any conventional flow device controller which operates the timers CIP functions etc via rotating drums and mechanical timing devices 111 Keegenerat or ae ures As previously noted in the HTST Design and Flow section pasteurized and raw milk in the regenerator section are separated only by thin stainless steel plates and a series of gaskets in the regenerator section Thus the requirement that the pasteurized milk MUST always be under greater pressure than the raw milk in the system In the event of leakage due to either gasket or metal failure the pasteurized milk will be forced into the raw side of the regenerator and not vice versa This pressure relationship must always be maintained during all phases of operations This includes initial start up during process
237. t STLR OUT OFF signifies a temperature below Cut In After completion of this test use the same procedure to return the unit to sequential display TESTING THE ELECTRONIC RECORDER CONTROLLER Early type The four test required for Electronic recorder controllers ERC s are A Programming of process values upon initial installation or when a change in the process is made B Instrument calibration quarterly C Cut in and cut out temperatures quarterly daily by the operator D Locking and sealing of instrument quarterly Tests A B and C are also to be conducted when Test 1 is performed TEST A PROGRAMMING OF PROCESS VALUES APPLICATION To all Taylor ER C Recorder controllers used in connection with continuous flow pasteurizers FREQUENCY Upon installation and whenever a process value needs to be changed CRITERIA The selected process variables shall be programmed with the values stated in this test APPARATUS none METHOD The regulatory official shall scan through the display prompts of the firmware for the recorder controller according to the vendor s operations manual and program the appropriate process values for HTST operation 316 Taylor ERC First Model Testing PROCEDURE 1 With the power off to the recorder controller open the back case and move the control switch to the unlocked run position Close the recorder controller and turn on power Set the following process values 2 Move display prompt
238. t or repair shall be made to permit stem to act freely in all positions with packing nut when applicable is fully tightened 5 3 DEVICE ASSEMBLY SINGLE STEM DEVICE Apparatus Sanitary fitting wrench and suitable tools for tightening the packing nut on the stem Method During diverted flow by temperature observe function of metering pump and all other flow promoting devices capable of causing flow through the holding tube when flow diversion device is improperly assembled Procedures a Place the flow diversion device in diverted flow either by lowering the temperature or by removing the STLR sensor from the water bath Disconnect the forward flow piping not the large 13H hex nut at the top of the 245 valve which negates any downward force on the hex nut and with all flow promoting devices in HTST system in operation and in diverted flow unscrew by one half turn the 13H hex nut which holds the top of the valve to the valve body This should de energize the metering pump and all other flow promoting devices capable of causing flow through the holding tube b With the HTST system in operation below the required process temperature diverted flow remove the connecting key located at the base of the valve stem The metering pump and all other flow promoting devices should be de energized Corrective Action If metering pump or flow promoting device fails to respond as indicated immediate checks of the device assembly the m
239. te 7 Repeat the above steps for the leak detect valve 8 Attach a new sealing wire to the air Shut Off Valve handles and record your results 250 PASTEURIZATION TESTING PROCEDURES TESTING METHOD TRI CLOVER DUAL STEM DEVICE 1 Remove the recorder controller temperature sensor from the water bath or cool the bath to a temperature that will allow diverted flow 2 Remove one actuator clamp On most dual valves this is the TOP CLAMP 3 Turn the mode switch on the FDD control panel to INSPECT 4 Once the valve has assumed the forward flow position disconnect the stem from the actuator 5 Turn the mode switch back to PRODUCT which will allow the valve to assume the divert position Turn on the metering pump switch The metering pump should not run Note At this time you may want to complete disassembly of the valve and inspect for construction gaskets O rings etc 6 Turn the mode switch back to INSPECT and allow the valve to assume the forward flow position 7 Reconnect the stem to the actuator 8 Turn the mode switch from INSPECT to PRODUCT and allow the valve to assume the divert flow position 9 Reconnect the actuator clamp Corrective Action If metering pump fails to respond as indicated an immediate check of the device assembly MICROSWITCH and wiring is required to locate and correct the cause 251 TESTING METHOD TRI CLOVER REVERSE ACTION FDD 1 Make certain the valves are properly a
240. ter In the case of mercury actuated general purpose thermometers the following additional specifications shall apply Magnification of Mercury Column To apparent width of not less than 1 6 millimet Number of Degrees per Inch of Scale Not more than 29 Celsius degrees or not more than 52 Fahrenheit degrees Case Metal provided with a fountain pen clip Bulb Corning normal or equally suitable thermometric glass ELECTRICAL CONDUCTIVITY MEASURING DEVICES Type Manual or automatic Conductivity Capable of detecting change produced by the addition of 10 ppm of sodium chloride in water of 100 ppm of hardness Other equivalent chemical solutions may also be used as desired Electrodes Standard Automatic Instruments Electric clock time divisions not less than 0 2 of a second 234 PASTEURIZATION TESTING PROCEDURES STOPWATCH Type Open face electronic or mechanical indicating fractional seconds Accuracy Accurate to 0 2 of a second Scale Divisions of not over 0 2 of a second Crown Depression of crown or push buttons starts stops and resets to zero Digital stopwatches operated as instructions prescribe 235 ll TEST PROCEDURES Equipment and field tests to be performed by the regulatory agency are listed and suitably referenced below The results of these tests shall be recorded on suitable forms and filed as the regulatory agency shall direct On an emergency basis the paste
241. ter whenever seal on speed setting is broken any alteration is made affecting the holding time the velocity of the flow such as replacement of pump motor belt drive or driven pulleys or decrease in number of HTST plates or the capacity of holding tube or whenever a check of the capacity indicates a speedup Criteria Every particle of milk shall be held for at least 15 seconds in both the forward and diverted flow positions Apparatus Electrical conductivity measuring device Appendix capable of detecting change in conductivity equipped with standard electrodes table salt sodium chloride suitable method of injecting saline solution stopwatch suitable container for salt solution Method The holding time is determined by timing the interval for an added trace substance to pass through the holder Although the time interval of the fastest particle of milk is desired the conductivity test is made with water The results found with water are converted to the milk flow time by formulation since a pump may not deliver the same amount of milk as it does water 1 285 Procedure a Examine the entire system to insure that all flow promoting equipment is operating at maximum capacity and all flow impeding equipment is so adjusted or bypassed as to provide the minimum of resistance to the flow There shall be no leakage on the suction side of the timing pump b Adjust variable speed pump including electronic pump control b
242. tes plus the filling time of the vat from the level of the recorder bulb sensor to the maximum level of normal operation pasteurization 4 When cooling is begun after the outlet valve is opened or is done entirely outside the vat the chart must show a holding time of 30 minutes plus the time necessary to empty the vat to the level of the recording thermometer bulb 5 These filling and or emptying times must be indicated on the chart by the operator by inscribing the start and end of the official 30 minute holding time 6 Upon close inspection vat pasteurization recording charts used that have been used must show clearly the four identifying holes marks which verify the chart has not been rotated or manually turned to give a false time line accuracy 51 VAT PASTEURIZATION 52 VAT PASTEURIZATION CHAPTER REVIEW 1 The requirements for vat pasteurization may be found in Section Item on pages of the current edition of the 2 Another good reference for vat pasteurizers may be found in 3 Currently vat pasteurizers found in many modern processing plants are used for products such as 4 Batch Pasteurization Time Temperature Standards Product Temperature Time Whole Milk Skim Milk Half and Half Eggnog cR _ Frozen Dessert 5 The PMO requires that if the fat content of the milk product is percent or more or if it contains added sweeteners or solids the specified minimum temperature shall
243. teurizers using direct steam infusion heating and using a steam pressure relief valve and a vacuum chamber orifice in place of a timing pump Frequency Upon installation and every 3 months thereafter or when a regulatory seal has been broken Apparatus No supplemental materials needed Criteria Every particle of product shall be held for the minimum holding time in both forward and diverted flow position The following controls are required a A steam infuser shell or feed line shall be equipped with a pressure relief valve This pressure relief valve shall be located and sized so that the total pressure insiede the infuser can never exceed the set point on this pressure relief valve b An orifice or restrictor permanently installed in a noticeable fitting shall be placed in the holding tube just prior to the vacuum flash chamber The opening in this orifice shall be sixed to insure a minimum product residence time at least as long as that specified in the chosen HHST standard c The size of the opening in the orifice or restrictor and the setting of the steam pressure relief valve shall be determined by trial and error Once an appropriate maximum flow rate has been determined and a legal minimum holding time has been calculated both the restrictor or orifice and the steam pressure setting on the pressure relief valve shall be sealed so that neither can be changed d The state regulatory authority shall keep records of the o
244. the boiling point and maintain temperature Prepare a second container with melting ice Place water baths within working distance of the recorder sensing element 3 Immerse the sensing element of the recorder in boiling water for not less than 5 minutes 2 minutes for electronic recorder controllers 4 Remove the sensing element from the boiling water and immerse in ater at a temperature within the testing range for the pasteurization process being used Allow a 5 minute 2 minutes for electronic recorder controllers Stabilization period for both indicating and recording thermometers Compare readings of the indicating and recording thermometers The recorder reading should be within 0 5 C 1 F plus or minus of the indicator thermometer reading 5 Remove sensing element from bath at operating temperatures and immerse in melting ice for not less than 5 minutes 2 minutes for electronic recording controllers 6 Remove sensing element from ice water and immerse in water at a temperature within the testing range for the process being used Allow 5 minute 2 minutes for electronic recorder controllers stabilization period for both indicating and recording thermometers Compare readings of the indicating and recording thermometers The recorder reading should be within 0 5 C 1 F plus or minus indicator thermometer reading 7 Re seal regulatory controls as necessary and record indicating and recording thermometer readings at step
245. the bottom of the flash chamber and is pumped to a homogenizer at about 170 F Homogenization pressures are generally set at 223 1500 to 3500 psi The product is then cooled to 45 F for ultra pasteurized product or 70 F for aseptic filling The flow diversion valve as is the DASI system is located at the end of the final cooling section and the temperature sensor is located the beginning of the holding tube If temperatures or pressures do not meet required pre set values the flow diversion device automatically diverts and the entire system is subjected to a sterilization process prior to restarting the product process Complete sterilization temperatures often exceed 295 F 224 HHST UP AND UHT SYSTEMS Ps U Eua E ikan p APOE NE hin MAC PME WAL vi OH ee P ODUCI V U TES CJ atat NOV ATE SOU TUBE amp ACUL TOn BOOSTER na Stean gt 58167 vav LEGEND VAPOR UNE s A AIR OPERATED VALVF AX AIR OPERATED ASEPTIC VALVE PATI GONE gt TS SENSOR cuaran varvi Be niuer varve LT LEVEL TRANSMITTER V S VARIABLE SPEED C SION SPECK varve SIGNA PNEUMATIC ya SIGNAL JUMPER 3 B pes noouct Remova B ssm 0 thar PRESSURE TRANSMITTER For CONE uPwa
246. the metering pump all requirements of the PMO are applicable 176 METER BASED TIMING SYSTEMS BASIC COMPONENTS OF METER BASED SYSTEMS A Centrifugal pump 1 Fixed speed 2 Variable speed B Magnetic flow meter A short piece of sanitary tubing containing two electrodes surrounded by a housing that contain coils which generate a magnetic field The electrodes used are either Hastelloy C4 Accurate Metering or Carpenter 20 SST ABB Kent Taylor Both meters use Teflon as the pipe liner as it is non conducting thus insulating the electrodes from the pipe Both Accurate Metering and Taylor use PTFE non filled virgin teflon for liners in food applications C Flow control valve Air operated sanitary design designed to regulate product flow D Flow recorder or SFLR Safety Flow Limit Recorder Controller with high flow alarm E Sanitary check valve or suitable fail safe air operated valve F Electronic transmitter transducer Converts an electronic signal to a pneumatic value 177 Ill TYPES OF SYSTEMS A System utilizing a single speed centrifugal product pump and flow control valve to regulate product flow 1 2 Magnetic flow meter Single speed centrifugal pump Sanitary check valve or suitable automatic fail safe valve Flow control valve Transmitter transducer Flow recorder controller with suitable alarms Suitable flow diversion device B System utilizing variable sp
247. the time required to deliver a known volume of water at the forward flow discharge line Repeat the test at least once to determine that the measurements are consistent c Repeat the stepsin paragraphs a and b of this procedure in diverted flow by measuring the flow using identical know volume at the discharge of the divert line d Select the greatest flow rate shortest delivery time for the known volume and calculate the flow rate in gallons per second by dividing the known volume by the time required to collect the known volume Multiply this value with the appropriate value in Table 12 to determine the required holding tube length e Determine the number and type of fittings in the holding tube and convert these to equivalent lengths of straight pipe with the use of Table 13 of this section Determine the total length of the holding tube by adding the equivalent lengths of the fittings to the measured straight lengths of pipe Record the num ber and type of fittings the number and length of straight pipe and the holding tube configuration for the office record If the temperature sensor is located at the beginning of the holding tube the holding tube shall be protected against heat loss by material that is impervious to water Reseal regulatory controls as necessary Alternate procedure For pasteurizers of large capacity the method of measuring flow rate at the discharge of the pasteurizer is inconvenient and the following a
248. this document all products that were processed during that period will be recalled and g The regulatory agency will remove the temporary seals retest the equipment and apply seals within 3 working days of notification by industry and h No Grade A dairy products will be processed after three working days without the affected equipment being tested and sealed by the regulatory agency 236 PASTEURIZATION TESTING PROCEDURES ll TEST PROCEDURES TEST 1 INDICATING THERMOMETERS TEMPERATURE ACCURACY Reference Item 16p E Application To all indicating thermometers used for the measurement of product temperature during pasteurization or aseptic processing including airspace thermometers Frequency Upon installation and once each 3 months thereafter or whenever the thermometer has been replaced or the regulatory seal on a digital sensor or the digital control box has been broken Criteria Within 0 25 C 0 5 F for pasteurization and aseptic processing thermometers and 0 5 C 1 F for airspace thermometers plus or minus a specified scale range Provided that on batch pasteurizers used solely for 30 minute pasteurization of products at temperatures above 71 C 160 F indicating thermometers shall be accurate to within 0 5 C 1 F plus or minus Apparatus 1 Test thermometer meeting specifications under Appendix Part 1 Provided that types other than mercury actuated may be used when they have
249. tic processing temperature d Reseal the regulatory controls as necessary and record the set point of the Flow Alarm the occurrence of flow diversion and the temperature of the water in the holding tube for the office record Corrective Action If the flow diversion device does not move to the diverted position when the frequency pen of the Recorder indicates a diversion a modification or repair of the control wiring is required 11 2C CONTINUOUS FLOW HOLDERS LOW FLOW LOSS OF SIGNAL ALARM Application To all continuous flow pasteurization and aseptic processing systems using a Magnetic Flow Meter System to replace a metering pump When testing aseptic processing systems the product divert system or product divert valve or acceptable control system may be substituted for the flow diversion device when it is referenced in this test 292 PASTEURIZATION TESTING PROCEDURES Frequency Upon installation and semiannually thereafter whenever seal on the Flow Alarm is broken any alteration is made affecting the holding time the velocity of the flow or the capacity of holding tube or whenever a check of the capacity indicates a speedup Criteria Forward flow occurs only when flow rates are above the Loss of Signal Alarm set point Apparatus None Method By observing the actions of the frequency pens on the recorder and the position of the flow diversion devise Procedure a Operate pasteurize
250. tilized as vat pasteurizers special consideration should be given to proper product agitation capabilities and other construction requirements of these type vats c All vat pasteurizer outlet valves must be fitted with stops which provide the operator with a physical indication of complete valve closure during the entire filling heating and pasteurization holding period operation d Outlet valves must be of the close coupled design that is designed so as to prevent the accumulation of unpasteurized milk in the milk passage of the valve when in the closed position 40 VAT PASTEURIZATION All vats used for pasteurization must be fitted with adequate means of continuous mechanical agitation f The requirements outlined in Ma 76 prohibits the practice of leaving the raw milk fill line to remain in place in the vat pasteurizer during the holding time phase since complete separation between raw and pasteurized milk product is required at all times g Outlet valves which are mounted vertically as on cone bottom vats must have a leak detector groove arrangement which will allow free drainage of any product past the plug while in the closed position Grooves must be curved or placed at such an angle to accomplish proper draining Diagrams of these valves may be found in the 3 A Standard 08 17 Part 2 drawings 100 28 and 100 29 2222 CLOSED IMPROPERLY CLOSED IMPORTANCE OF PROPER STOP
251. time temperature exposure sufficient to destroy or slow down the growth of spoilage microorganisms inhibit enzyme activity kill any disease producing bacteria and yet retain the desired properties of the product Fast flowing liquids such as wine fruit juices milk etc lend themselves to efficient handling in standard pasteurizing equipment CHAPTER REVIEW 1 ALL PASTEURIZERS MUST MEET THESE THREE REQUIREMENTS 2 PASTEURIZATION DEFINITION D VALUE DEFINITION 31 BACKGROUND AND HISTORY 3 Fill in the blanks 1 Pasteurization temperatures are usually ______ F___ which destroys _________ 2 Canning processes are at temperatures above and aimed at destruction all a statistical entity It is specific for 4 The last revision of pasteurization temperatures was the 1940 s and based on the destruction of the organism which is responsible for the disease 5 Three general types of bacteria thrive at different temperature ranges They may be classified as a 6 Most pathogens are found in the a b or c grouping 32 BACKGROUND AND HISTORY 33 BACKGROUND AND HISTORY 34 VAT PASTEURIZATION VAT PASTEURIZATION PURPOSE To understand the basic principles and public health reasons for the requirements of proper design and operation of a batch type or vat pasteurizer OB ECTIVES 8 To understand and be able to list and explain the compliance and construction re
252. tly serving as a model for many food control and inspection programs 20 BACKGROUND AND HISTORY For example the Interstate Shellfish Sanitation Program and many of the current HACCP hazard analysis of critical control points concepts were borne from the basics and diligence of milk inspection principals regulations and methods of inspection Consumers can now be relatively assured of the safe and wholesome quality of milk products purchased from the retail shelves Seldom are milk products implicated in major food borne outbreaks The development of methods procedures equipment and yes regulations and ET standards over the years has resulted in an effective method of providing the consumer one of the safest and most wholesome foods available D o in the nation today 21 BACKGROUND AND HISTORY COURSE ECTIVES AT THE END OF THIS COURSE THE PARTICIPANTS SHOULD BE ABLE TO Describe the basic process methods principles and requirements of Batch High Temperature Short Time HTST and Higher Heat Shorter Time HHST pasteurization systems Be able to explain the reasons for and methods used to evaluate and regulate the TIME TEMPERATURE PRESSURE relationships in pasteurization systems able to list the basic and auxiliary equipment components of pasteurization systems including vat HTST meter based HHST systems and give the PMO requirements and public health reasoning for le
253. to a vacuum condenser and the vacuum chamber is not physically separated from the vacuum condenser satisfactory methods must be installed to prevent adulteration of the product with water in the condenser This is usually accomplished by installation of automatic shut off valve on the water feed line This valve would automatically shut off the water in case the condensate product pump shuts down for any reason 3 All systems must be equipped with an approved indicating thermometer at the end of the holding tube as close as practable to the recorder controller sensor It may be either of the mercury in glass or an acceptable electronic type Figure 58 ratio controller instrument 208 HHST UP AND UHT SYSTEMS FULSCOPE RATIO CONTROLLER _ VACUUM _ REGULATOR LJ ATMOSPHERIC AIR Figure 59 Ratio Controller Placement with Direct Steam Systems 209 OO PASTEURIZED DIVERSION Q Q Device TCR uum mune BACK PRESSURE CONTROL DEVICE STEAM INJECTOR DIFFERENTIAL PRESSURE LIMIT CONTROLLER d LEAK DETECT LINE DIVERT LINE a P VIN BOOSTER PUMP TIMING PUMP Figure 60 Steam injection pasteurization controls HHST with steam injection vacuum cooling and flow diversion device at end of system 2 all divert leak detection and recycle lines which return to the constant level tank must break to atmosphere at least two pipe
254. tors are valved out c After the metering pump and other flow promoting devices have stopped or valved out the device assumes the forward flow position d Repeat the above procedure by moving the control switch to the clean in place CIP position for those systems in which no milk flow promoters are allowed to operated during CIP d Record test results and seal the control enclosure as necessary Corrective Action If the above sequence of events does not occur either a timer adjustment or wiring change is required 256 PASTEURIZATION TESTING PROCEDURES 5 8 CIP TIME DELAY RELAY Application To all continuous flow pasteurizer systems in which it is desired to run the timing pump and or other flow promoting devices during CIP without the controls required during processing Criteria When the mode switch on the flow diversion device is moved from process product to CIP the flow diversion device shall move immediately to the diverted position and remain in the diverted position for at least 10 minutes with all controls and safe guards required in product mode in placed and functioning before starting its normal cycling in the CIP mode In HTST systems the booster shall be de energized during this 10minute time delay Note Also any flow promoting devices capable of causing improper pressure relationships in the milk to milk regenerator must either be deactivated or automatically valved out of the system during this t
255. trol the operation of the flow diversion dievice Test 2 3 also applies to aseptic processing systems in which the differential pressure controller is used to control the flow diversion device product divert system product divert valve or other acceptable control system Frequency Upon installation each 3 months thereafter and whenever the differential pressure controller is adjusted or repaired or whenever the regulatory seal is broken Criteria The booster pump shall not operate or the pasteurizer shall not operate in forward flow unless the product pressure in the pasteurized side of the regenerator is at least 6 9 kPa 1 psi greater than the product pressure in the raw side of the regenerator When the differential pressure controller is used to control the flow diversion device on HHST systems and improper pressure occur in the regenerator the flow diversion device shall move to the diverted flow position and remain in diverted flow until proper pressures are re established in the regenerator and all product contact surfaces between the holding tube and flow diversion device have been held at or above the required pasteurization temperature continuously and simultaneously for at least the required pasteurization time as defined in Definition S of this Ordinance Apparatus A sanitary pressure gauge and a pneumatic testing device described under PRESSURE SWITCHES Test 9 1 above can be used for checking and adjusting the differential
256. ts FDA s Milk Safety Branch State Milk Rating Officers state and local milk regulatory individuals and the milk industry and academia who have all contributed to the further development of this training manual FOREWORD This Course is designed primarily for state milk regulatory and rating personnel local milk inspection staff FDA milk specialists and investigation personnel elements of the milk industry including quality assurance plant management plant engineers industry consultants colleges and university staff and students military food and milk specialists and other personnel engaged and concerned with the safe processing of milk and milk products Fundamental principles of the theories and sanitary operation of milk pasteurization systems are presented in both lecture and class participation formats Lectures and demonstrations are enhanced with visual aids handouts Slides overheads and videos Class discussions and problem solving sessions constitute a vital entity in this course The trainees are ultimately involved in the hands on portion using actual pasteurization controls and equipment in the classroom This demonstrates the proper methods to be used in the testing of equipment while enabling the participants to become familiar with the basic components of actual milk plant equipment This course manual is a collective reference booklet to equip the course attendees with those principles theories and regulato
257. ts own deadband Press MOD Key and then use the UP DOWN Keys to modify 8 Press the ENTER Key to program the new value 9 Press the RESET Key 10 Re position the security shunt to the run upper position Verify that EEPROM s U7 and U8 are labeled as noted during initial installation Re seal the chart plate Test 3 Time Accuracy With the unit in the Run mode and while a chart is being printed use an accurate watch to test for time accuracy as follows 1 Begin timing when the unit prints a major time line solid color 2 Stop timing when the mechanism prints the second minor time line second dotted line The elapsed should be 30 minutes 315 Test 8 Thermometric Response The standard test may be used except theat the display must be utilized to start the stopwatch at eh proper temperature If the display has been configured to opeate in the seuintial mode the test will be simplified by first programming it to display in the continuous mode as follows 1 Wait until the display reads STLR INP STLR OUT Press the DISP Key twice The display will read MODIFY DISPLAY PARAMETERS 2 Press the DOWN Arrow Key The display will read DISPLAY MODE CONTINUOUS SEQUENCE flashing 3 Press the Scroll Key Now CONTINUOUS will be flashing 4 Press the ENTER Key and then RESET Key The display will now continuiusly display the STLR Temperature constantly Just below this line on the display will be the status of the STLR Outpu
258. ture reading on the controller when the test lamp lights cut in temperature Record the temperature for the office record b After the cut in temperature has been determined and while the bath is above the cut in temperature allow the bath to cool slowly at a rate not exceeding 0 5 C 1 F per 30 seconds Observe the temperature reading on the controller when the test lamp goes out cut out temperature Determine that the cut out temperature on the thermal limit controller is equivalent to or greater than the chosen pasteurization or aseptic processing standard Where adjustment is necessary refer to manufacturer s instructions After adjustment repeat the procedure above and when the results are satisfactory record the results for the office record Repeat the procedure for the other two sensing elements i e the vacuum chamber and flow diversion device Rewire the test lamp in series with the control contacts from each sensing element respectively When proper cut out temperatures have been verified for all three sensing elements seal the controller system 284 PASTEURIZATION TESTING PROCEDURES TEST 11 CONTINUOUS FLOW HOLDERS HOLDING TIME Reference Item 16p B Continuous flow holders shall be tested for holding times by one of the applicable tests 11 1 HTST PASTEURIZERS except for magnetic flow meter systems Application To all HTST pasteurizers Frequency Upon installation and semiannually thereaf
259. uge to excessive pressure which might damage them This can be done by first closing off the air pressure regulating valve and opening fully the bleeder valve these may then be manipulated slowly to bring the air pressure in the testing device within the desired range A test light of proper voltage can be placed in series with the pressure switch contact and in parallel with the electrical load booster pump starter so the actuation point may be readily determined Method Check and make adjustment of pressure switch so as to prevent the operation of the booster pump unless the pressure of the pasteurized milk side of the regenerator is greater by at least 6 9 kPa 1 psi than any pressure that may be generated on the raw side Procedure Early type a Determine maximum pressure of booster pump 1 Install sanitary pressure gauge in tee at discharge of booster pump 2 Operate the pasteurizer with water with the flow diversion device in forward flow position the metering pump operating at minimum speed pos sible and the booster pump operating at its rated speed If vacuum equipment 268 PASTEURIZATION TESTING PROCEDURES is located between the raw outlet from the regenerator and the metering pump it should be bypassed while this determination is made 3 Note maximum pressure indicated by pressure gauge under these conditions b Check and set the pressure switch 1 Install a sanitary pressure gauge of known accur
260. uirements of meter based systems as they relate to time temperature and pressure relationships within the HTST pasteurization system To become familiar with the required HTST tests for systems using magnetic flow meters within the system as a replacement for the conventional timing pump 171 BACKGROUND AND THEORY Early in 1980 the first meter based system was submitted for compliance review to the FDA s Milk Safety Branch The proposal was for the use of a magnetic flow based system to be used in lieu of the conventional timing pump in HTST systems These systems presented a radical departure from conventional HTST systems therefore the first installations in dairy plants were under close surveillance by the regulatory authorities Initially these systems were limited to use with non regenerator systems processing milk products with a viscosity no greater than whole milk Meter based systems are based on the principles of electromagnetic induction first reported by Michael Faraday in 1839 Systems based on these theories were first applied in industrial use in the early 1950 s The theoretical basis of a meter based system can be stated as follows conducting fluid passing at right angles through a magnetic field induces a voltage across the conductor This theory may be calculated using the following formula where E generated signal B magnetic flux density v velocity d distance between electrodes
261. ulting calculations will provide the required length of the holding tube for the process These calculations follow the equation A BXC where A holding tube length inches B measured pumping rate gallons per second holding tube length from Table 1 inches per gallon per second Example 1 The health authority knows the time temperature standard and flow rate and wants to know the required length for the holding tube The pasteurizer has a nominal capacity of 10 000 pounds per hour The time required to fill a 10 gallon can with water from the pasteurizer is 32 5 seconds The temperature time standard is 204 F for 0 05 second and the holding tube is 2 inches in diameter The pumping rate is 10 gallons divided by 32 5 seconds which is 0 308 gallon per second 205 The required holding tube length A is calculated from Equation 1 A BxC The pumping rate B is 0 308 gallon per second and from Table 1 the holding tube length C required for a holding time of 0 05 second with a pumping rate of 1 gallon per second in 2 inch diameter tubing is 9 4 inches For this example A 0 308 x 9 4 A 2 9 inches Therefore the holding tube must be at least 2 9 inches long Example 2 The health authority knows the temperature time standard and the actual holding tube length and wants to know a the maximum permissible pumping rate The pasteurizer has a nominal capacity of 60 000 pounds per hour and the temperature time st
262. um in case of regenerator plate or tubular failures The recorder controller is set to divert the system when the lowest presssure of pasteurized or aseptic product in the regenerator fails to exceed the highest pressure of heat transfer medium in the pasteurized or aseptic side of the regenerator by at least 6 9kPa 1psi 4 n the case of aseptic processing systems a differential pressue recorder shall be used to monitor and record pressures of the asepic product and the heat transfer medium 5 Since the FDD is located at the end of the cooler section and because the entire system must undergo re sterilization at pasteurization temperatures following diverted flow the balance tank overflow height and vacuum breaker requirements are not required Also the requirement for a time delay to allow the FDD to flush the are between the flow divert and leak detect valve is not applicable for HHST or UHT systems 196 HHST UP AND UHT SYSTEMS 6 Flow promoting devices that may affect the proper regenerator pressures shall not be located downstream from the pasteurized milk outlet 7 The heat transfer medium pump shall be wired so that it can operate only when the metering pump is in operation Indirect heating 1 Requires that forward flow commences only after both sensors at the holding tube and at the FDD located after the pasteurized or aspectic milk has exited the system have reached the minimum cut in temperature 2 This test
263. umps is their location in the system Remember a centrifugal pump placed between the raw milk balance tank and the raw milk inlet to the milk to milk regenerator is always considered as booster pump even though it may appear identical to other centrifugal pumps in the pasteurization system 145 The following illustrations depict two of the more common type of booster pump differential controllers These pressure differential controllers PDC s are interwired to provide constant control over the booster pump and deactivate the booster pump immediately should regenerator pressures approach the 1 psi required differential FINE ZERO ADJUSTMENT pow MICROMETER POINTER YOKE INKS PRESSURE SWITCH TEST PUS TAKE OH COARSE AIR SUI AIR FILTI REGENERATOR INLET MEASURING ELEMENT REGENERATOR OUTLET MEASURING ELEMENT LOCATION OF COMPONENTS Figure 40 Booster Pump Controls 146 HTST Auxiliary Equipment b One of the early methods of booster pump controls included a combination sanitary pressure gage and switch This gage switch is installed at the exit to the pasteurized regenerator The switch must be set and sealed at a pressure at least 2 pounds greater than the maximum pressure generated by the booster pump A major problem with these type controls is inability to constantly monitor control pressures within the raw side of the regenerator An accurate sanitary pressure gaug
264. urization equipment may be tested and temporarily sealed by a dairy plant employee provided the following conditions are met 5 1993 a The individual applying the seal s is employed in a supervisory capacity by the plant in which the seal was removed b The individual has satisfactorily completed a course of instruction acceptable to the regulatory agency on tests controls for pasteurization equipment that includes a minimum of 8 hours classroom instruction and c The individual has demonstrated the ability to satisfactorily conduct all pasteurization control tests in the presence of a regulatory official within the past year and d The individual is in possession of authorization from the regulatory agency to perform these tests and e The individual will immediately notify the regulatory agency of the time of the shutdown that would necessitate the removal of the regulatory seals Permission to test and seal the equipment must be obtained for each specific incident The individual will also notify the regulatory agency of the identity of the controls affected the cause if known of the equipment failure the repairs made and the result of testing when completed The individual will provide the identity and volume of products processed during the period that temporary seals were applied to the regulatory agency and f If regulatory tests reveal that equipment or controls are not in compliance with the provisions of
265. usion Heating 3 months Controller Sequence logic HHST and 3 months Aseptic 12 2 or 12 2 Product pressure control switch setting MEE HHST and Aseptic Remarks IDENTITY OF PASTEURIZER LOCATION DATE SANITARIAN 353 354 The evaluation of Computer Controlled Milk Pasteurization Systems Reference FDA MSB MI 88 11 355 CRITERIA FOR THE EVALUATION OF COMPUTERIZED SYSTEMS FOR GRADE A MILK PASTEURIZATION SYSTEMS BACKGROUND Computers are different from hard wired controls in three major categories To provide adequate public health protection the design of computerized systems must address these three major differences 1 The computer unlike conventional systems which provide full time monitoring of the public health controls performs its tasks sequentially The computer may be in real time contact with the flow diversion device for only one millisecond During the next 100 milliseconds or however long it takes the computer to cycle one time through its tasks the flow diversion device remains in forward flow independent of temperature in the holding tube Normally this isnot a problem because most computers can cycle through 100 steps in their program many times during one second The problem occurs when a the public health computer is directed away from its tasks by another computer or b the computer program is changed or C seldom used J UMP BRANCH OR GO TO INSTRUCTION diverts the comp
266. uter away from its public health control tasks 2 computerized system the logic is easily changed because the computer program is easily changed few keystrokes at the keyboard will completely change the control logic of the computer program Conversely hard wired systems require tools and a technician to make wiring changes Once the hard wired systems were properly installed and working it was never changed This problem can be solved by sealing the access to the computer Some procedure is needed to ensure that the computer has the correct program when the regulatory seal is applied 3 Error free computer installations cannot always be assured For public health controls the computer program must and can be made error free Since the programs required for public 356 health controls unlike the very large complex programs are relatively brief error free installations are attainable GLOSSARY Address The Numerical label on each input or output of the computer The computer uses this address when communicating with the input or output Computer A very large number of on off switches arranged in a manner to sequentially perform logical and numerical functions Default mode The pre described position of some memory locations during start up and standby operations EAPROM An electrically alterable programmable read only memory Individual memory locations may be altered without erasing the remaining memory EEPROM
267. veloped by vendors with FDA concurrence 6 The effect of high temperature humidity shall be documented The device should show no effect after exposure to 100 F and 80 relative humidity for 7 days 7 Both probe and display case shall be constructed so that they may be sealed by a health authority 8 Calibration of the device shall be protected against unauthorized changes 9 The device shall be protected against unauthorized component or sensing element replacement Replacement of any component or sensing element shall be regarded as a replacement of the indicating thermometer and subject to health authority inspection and all applicable PMO tests 10 The sensing element shall be encased in appropriate material constructed so that final assemble meets PMO Item 11 Construction 76 Basic HTST Pasteurization F RECORDER CONTROLLER STLR 1 Purposes To automatically record pasteurization temperatures and times a record of the position of the glow diversion device and to automatically control the position of the flow diversion device 2 Location The temperature sensor of the recorder controller shall be located within 18 inches of and up stream from the flow diversion device 3 Design and Operation The recorder controller or STLR is an electronic instrument actuated by either a Bourdon coil attached to an ether derivative water and glycerin filled capillary which responds to temperature cha
268. verlapping information c Charts must be retained for at least 3 months d Temperatures recorded on the charts verify that the higher minimum required temperatures for products containing added sugars or higher fats have been met 96 Basic HTST Pasteurization 97 i SQN ELEME SS eee 2 YY 5 77 eE NRK 2222 RON 22 Mr SRO TAN MMe 228 i UME ASME ns Me SEE Sih a Lo mm 3119 11 MET P 2 II SN 98 Basic HTST Pasteurization FLOW DIVERSION DEVICE SINGLE STEM 1 Purpose Too safely and accurately control and separate raw and pasteurized product flow The single stem flow diversion device is a specially designed three way valve that in conjunction with a recorder controller is capable of automatically controlling the direction of product flow in a pasteurizing system Figure 21 Single Stem Flow Diversion Device 99 2 Operation a The single stem flow diversion device is air activated for the open position forward flow and spring activated for the closed divert or fail safe position To activate open the valve to the forward flow position compressed air is admitted past the solenoid and presses down against the diaphragm This compresses the spring and
269. w where considerable mixing occurs across a pipe cross section and the velocity is nearly the same across this section Turbulent flow occurs most frequently in less viscous liquids and is often characterized by higher friction losses than would be expected VACUUM BREAKER An air relief valve held in the closed position by product flow pressures and which opens and admits air when the product pressure goes below atmospheric pressure Uses include maintaining proper pressures in a milk to milk regenerator during system shut down and preventing suction of product past the flow diversion device during operation Other uses are to provide protection on pasteurized installed vacuum chambers 341 VOLTAGE The force between the electrical leads or from one lead to ground It is measured across two unconnected leads open circuit voltage and standard voltages are 6 12 24 110 220 or 440 Neutral or ground is used as the second lead for measurement of the lower voltages single phase 342 Bibliography References Abele C A E Wallenfeldt History and Development of Grade A Program in America University of Wisconsin booklet 1970 Eau Claire WI Alloy Products Corporation Instruction Manual Model FDV 6800 FDV 7500 and Aseptic Model FDV 7800 A P C Flow Diversion Stainless Steel Sanitary Valves Bulletin C1013 and C2020 Waukesha WI Anderson Instrument Co Inc Anderson Sanitary Differential Pressure Switch JD Series Bulletin No
270. with FDA by the Process Authority who shares responsibility for plant operations In these systems if sterility is lost for any reason pressure or temperature then flow in and out of sterile surge tanks is interupted using a product diversion system or valve the packaging process is immdiately interrupted and the entire system including up to the filling packaging machine is re sterilized prior to resuming operation International Paper Aseptic UHT systems also require identification of temperature indicating devices differential pressure recorders sterile air pressure at the filler critical steam seals valves steam blocks etc a recorder at the final heater outlet and a process deviation log or record Aseptic systems also require a differential pressure recorder controller so that pressures of the aseptic product and heat transfer medium are automatically controlled and recorded Diversion of the product must occur when the aseptic product pressure drops to within 1 psi of the heat transfer medium pressure Location of the pressure sensors for these controls are 216 HHST UP AND UHT SYSTEMS a At the heat transfer medium water inlet on the aseptic side of the regenerator and b At the aseptic product outlet of the regenerator Note Forward flow shall not occur until all product contact surfaces between the holding tube and the FDD are held at or above the required STERILIZATION tempe
271. y crude however many are simply prototypes of the equipment we see in large modern dairies today It is important to note here that the concepts of continuous agitation and processing were employed in Fjords system known then as the Danish Pasteurizer Denmark enacted a law in 1898 requiring the heating of all calf fed milk to 185 F to prevent the spread of bovine tuberculosis This was indeed one of the first forerunners of modern commercial milk pasteurization Nathan Stauss a noted philanthropist in 1893 saw the marketing advantage of heating milk for infant feeding and later financed a chain perhaps the first real milk franchise of what he called milk depots in New York City He utilized pre sterilized glass bottles dry heat method and the milk was heated to 167 F for 20 minutes cooled and sold for consumption Some adversaries believed that destruction of some of the organisms in milk could allow others to produce toxins in the milk cause undesirable flavor problems and destroy many nutrients Fortunately however researchers furthered Pasteur s experimentation and proved that the use of lower temperatures destroyed spoilage organisms and incidentally pathogens After Park and Holt had showed evidence of the positive attributes of feeding pasteurized vs raw milk to infants in tenement houses in 1903 the United States Public Health Service began studies and confirmed the public health benefits of he
272. y either the application of heat or suitable chemicals used in accordance with good manufacturing practices SAFETY THERMAL LIMIT CONTROLLER The term sometimes used interchangeably when referring to the recorder controller SOLENOID An electronically operated valve used in to open or close a valve or to open or close a magnetic relay switch SNAFU Situation normal all fouled up STUFFING PUMP Any centrifugal pump used in the system for the purposes of enhancing product flow to a component other that those located between the balance tank and the raw regenerator TIME DELAY RELAY TDR An adjustable timer either mechanical or electronically controlled used to maintain a set time period equal to or greater than the required minimum All required TDR s must be sealed by the regulatory agency TIMING PUMP Sanitary positive displacement type rotary or piston or in the case of meter based systems a centrifugal product pump which provides a constant measured rate of flow to the continuous pasteurization system Homogenizers may be used as timing pumps since they are piston type always odd numbers of pistons pumps and positive displacement pumps All timing pumps are capable of crating suction and do not slow down under discharge pressure THROTTLING VALVE A spring to close valve used in conjuction with a magnetic flow meter timing system having a single speed timing pump to control flow speed of product TURBULENT FLOW Flo

Milk Pasteurization Training Manual 8th Edition

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