Creating a Custom Calibration
Contents
1. a custom calibration When measurements are taken using RESEARCH 1 the values shown don t actually show the fat percentage of the sample instead they give a representation of the sensor measurement for the sample When you set out to create a custom calibration use RESEARCH 1 for measurements on fish This will give you the best accuracy 3 2 The theory of a custom calibration This is a simplified view of the principle of a custom calibration Distell Technical note Custom Calibrations Page 3 When the Fatmeter is used on a piece of fish then there is a specific sensor measurement called the reference value A custom calibration allows you to relate that sensor measurement to a fat measurement called the analysis value When there is more than one pair of reference and analysis values then we can work out a best fit approximation to cover the whole range of reference values We can then take any sensor measurement reference value and find the corresponding fat content analysis value The quality of the custom calibration is partly based on the quality of the best fit approximation This in turn depends on the number of data points that are available More data is better If you have only a few data points then the calibration will not be reliable 3 3 Howto choose the sample fish Every custom calibration begins with taking measurements on a set of sample fish It is very important to get a wide range of fat contents in2. ensure that accurate results are obtained Ensure that the identity of the fish is recorded along with the laboratory analysis because you need to be able to connect the original Fatmeter reading with the laboratory analysis figure 5 Creating the custom calibration 5 1 Requirements To create a custom calibration you will need e The Distell Data Management System software e The calibration file with a DCF extension containing the reference calibration normally RESEARCH 1 for the meter used to take the measurements this was supplied with your meter but we can send a copy by email if required e The reference data recorded from the Fatmeter e The analysis data recorded from the laboratory analysis 5 2 Creating the calibration Launch the Data Management System and click on Create custom calibration under the File menu The Custom Calibration Data window will open The first step is to load in the DCF file for the meter used to take the measurements This should be on the CD that was supplied with the meter 5 2 1 Loading the reference DCF file First click the Browse button and find the DCF file or simply type in the filename Distell Technical note Custom Calibrations Page 5 1 Locate reference calibration c 2 Choose reference calibration Then click the Load button to load the file into the DMS 5 2 2 Choose the reference calibration Select the calibration used to make the Fa
3. on the Fatmeter when the calibration is selected It is limited to a maximum of 12 letters and numbers You should ensure that the calibration name is different to any other calibration that you have in the meter 5 2 6 Select a grouping method To select the correct option here check your Fatmeter menu options Distell Technical note Custom Calibrations Page 6 e lf you have separate Product and Research menus for selecting calibrations then choose Separate This will be the case on newer meters or meters that have recently been upgraded e lf you have a single calibration selection menu that combines all the calibrations research and product then select Combined This is only the case on older meters 5 2 7 Select a research slot The Fatmeter has a bank of calibration slots for research purposes beginning with Research 1 Your meter was supplied with a guide to which slots hold which calibrations This option decides which slot your custom calibration should be loaded into Note that it is your responsibility to make sure that you don t overwrite an existing calibration You should therefore keep a record of which slots are assigned to custom calibrations Note also that the DMS can create a custom calibration for a high numbered slot e g slot 9 that your meter does not have access to You can only access the slots listed on the guide so you should ensure that you custom calibration uses one of those slots 5 2 8
4. Distell Technical note Custom Calibrations Page 1 Creating a Custom Calibration DISTTELL com J 1 Introduction The Distell Fatmeter reports the fat content in fish and to do this it takes a measurement using a microwave sensor The sensor transmits a very low power high frequency signal into the sample being measured then analyses the response The sensor response is affected by the mix of fat water and body solids in the sample The body solids component for a given species is generally quite constant and the main variables are fat and water content The Fatmeter can report the fat content with good accuracy if it knows how the sample s fat and water content are related and that relationship is what we will explore in this document Note that this document is based around measuring fish but the same principles apply for our Meat Fatmeter Also this applies to naturally occurring fish and meat rather than man made products like hamburger 1 1 Fat content What do we mean by fat content Different Fatmeter users have different areas of interest and that means that sometimes they don t want the fat content of the whole fish Different target measurements include e The fat content of the entire fish including skin fins bones etc e The fat content of the fish fillets e The fat content of a specific section of the fish When we talk about the fat content of a sample therefore it could mean one of these three differe
5. Save the custom calibration Click on Save data to save the custom calibration as a DCF file This file can be uploaded to your meter using the DMS Check the meter s user manual for details on this procedure Distell Technical note Custom Calibrations Page 7 1 Locate reference calibration 3 Enter measurement data Reference max 12 letters numbers 1 2 3 4 a 6 i ta 9 10 11 1 Data required Value must be between 0 1 and 99 9 5 3 Using the calibration in a different meter The process described here covers creating a custom calibration for the same meter that was used to take the measurements on the sample fish If you want to use the custom calibration in a different meter then you can do so without taking new measurements Instead you should take the following steps e In section 5 2 1 Loading the reference DCF file load the DCF file for the meter that will use the custom calibration rather than the meter that was used to take the measurements e In sections 5 2 6 and 5 2 7 refer to the guide for the meter that will use the custom calibration rather than the meter that was used to take the measurements Distell Technical note Custom Calibrations Page 8 e When you save the custom calibration you should include the serial number of the target meter in the filename This will make it easier to keep track of which DCF file goes with each meter Each Fatmeter has tiny variations in se
6. curate your calibration will be This is because there are always small variations in the course of the sampling e g the position of the sensor on the fish the distribution of fat in the fish laboratory technique variations etc Having many samples will reduce the error introduced by those variations 3 5 Gathering data the first step in creating a custom calibration Once you have selected a set of sample fish you can start taking measurements with the Fatmeter Each sample fish should be uniquely identified e g by storing it in a sealed marked container and Fatmeter reading should be recorded on paper alongside the identity of the fish that it came from Remember each measurement on fish should be done following the guidelines in the Fatmeter User Manual so that each fish is represented by an average value of multiple readings Once all the fish have been measured with the Fatmeter the fish can go on to the next stage 4 Laboratory analysis The laboratory analysis should be performed on the fish according to what your custom calibration will represent For example e f your custom calibration will represent the whole fish then the laboratory analysis should be performed on the whole fish e lf your custom calibration will represent the fat content of fillets in brine then the laboratory analysis should be performed on fillets in brine The laboratory process is not perfect and you should work with your chosen laboratory to
7. e process will affect the accuracy of a calibration The Fatmeter can however give a high level of confidence in product consistency simply because the measurements can be checked against a standard from one day to the next
8. fat content of the fillets as determined by laboratory analysis 2 2 Different calibrations for different target measurements In section 1 1 Fat content we showed different ways to think of the fat content of a fish The J MACKEREL 1 calibration represents the fat content of the trimmed fillets but there is another Jack Mackerel calibration JMMACKEREL 2 that represents the fat content of the whole fish including head tail fins skin roe and flesh In this way we can have multiple calibrations for a single species This allows us to accommodate some of the factors that affect the measured fat content of a fish such as e Seasonal factors e Processing methods e Specific sections of the fish A detailed list of the fish calibrations available is on the Distell website www distell com 2 3 What is a custom calibration A custom calibration is a calibration where the end user supplies the calibration data rather than one that has already been developed by Distell There are various reasons why a custom calibration might be useful e The target fish species does not have an existing calibration e The fish will be processed in a way that is not covered by an existing calibration e Adifferent laboratory method is being used so a different range of results is needed 3 Gathering sample data 3 1 The RESEARCH 1 calibration Every Distell meter contains the RESEARCH 1 calibration This calibration is there to help you create
9. fferent options for this 6 1 1 Option1 In this example the reference data is gathered on the processed fish and then laboratory analysis is performed as usual Following the steps in this document you would then have a custom calibration that represents the fat content of this producer s herring processed in exactly the way that the sample was processed when measured on processed product normally minced product rather than brined fillets This allows the producer to assess the fat content of the processed product directly 6 1 2 Option 2 This example involves gathering reference data from the raw unprocessed herring The fish is then processed by the producer s standard method and sent for laboratory analysis as normal A custom calibration can now be developed and the calibration represents the fat content of this producer s herring processed in exactly the way that the sample was processed when measured on raw fish This allows the producer to predict the fat content of the final product by taking measurements on the raw fish before processing 6 1 3 The impact of processing The main point in these examples is that in both cases the custom calibration represents the product after processing It is vital to understand that the custom calibration will only be valid if the fish is processed in exactly the same way every time Distell Technical note Custom Calibrations Page 9 If for example the fish are cured for an ext
10. nsor characteristics when compared to another meter When a Fatmeter is prepared by Distell these variations are removed by preparing each meter s calibrations individually In the same way each custom calibration is unique to an individual meter specifically the meter whose reference calibration was selected in step 5 2 1 If you create a custom calibration for meter X but load it into meter Y then it will not give correct results In summary you need to create a new DCF file for each Fatmeter but you can use the same reference and analysis data for each one 6 Measuring processed food At the start of this document we said that the custom calibration process applied only to natural product rather than man made product We will take a moment to explain what this means When natural fish is processed into a man made product the ratio of fat to water will usually change Curing smoking and brining for example will remove some water from the fish and the amount of water removed depends on how long the process lasts It is still possible to use the Fatmeter on processed food but only if the processing method is identical for each batch of fish 6 1 An example Matjes Herring Matjes herring is a Dutch speciality where herring fillets are cured in salt then stored in brine Even though it has been heavily processed and the water to fat ratio has changed due to curing we can still create a custom calibration We will consider two di
11. nt measurements or other measurements that are used by different organisations around the world 1 2 Ratio of Fat to Water Here are some examples of how the water and fat content can vary with different fish species North Sea Whiting Dogfish North Sea Mackerel Water 74 Water 9 Fat 17 6 Fat 9 Since the ratio of fat to water can change for different fish the Fatmeter needs to know how to relate the fat content to the measured water content The relationship is called a calibration A Fatmeter calibration represents the relationship between the meter s sensor measurements and the fat content of the sample Distell Technical note Custom Calibrations Page 2 2 Calibrations 2 1 Example calibration An example of a calibration would be J MACKEREL 1 This is our Jack Mackerel calibration and it represents the fat content of two trimmed fillets without skin You can find out more about this specific calibration at http www distell com downloads charts JMackerel1 pdf This calibration provides a mapping from the range of Fatmeter sensor measurements to actual fat percentages The calibration was created by taking a range of actual fish samples and recording the sensor measurements The samples were then sent for laboratory analysis and the fat percentages were mapped to the sensor measurements In this way the Fatmeter can when the J MACKEREL 1 calibration is selected give a fat percentage reading that represents the
12. ra few days or the brine mixture changes or the fish are allowed to dry or if any other part of the process changes then the custom calibration will not be valid The calibration was created to represent a specific process but now the process has changed 6 2 A more useful application We know that variations in fish processing can cause the Fatmeter readings to change Many Fatmeter users have found this helpful in checking the day to day consistency of their processing Since the results from the Fatmeter will change if the process changes it follows that if the Fatmeter results stay the same within a margin for error then the process has not changed So the Fatmeter can be used as an assurance of consistency by 1 Using the Fatmeter to establish a normal reading for the processed product then 2 Checking that the processed product continues to show the same normal reading If the processed product gives a different reading then that can indicate that some part of the process has changed and appropriate checks can be carried out to find out what has happened 6 3 Summary Natural fish are generally very predictable in terms of the mix of fat water and body solids which is why one calibration can work on a whole species Once processing is introduced however the mix changes and many variables are introduced This does not mean the Fatmeter can t be used on processed food but it is important to be aware of how changes in th
13. the sample fish These graphs show two different situations Graph A shows a sample where all the fish have a similar fat content Graph B shows a sample where the fish cover a wide range of fat content from low to high narrow p E va 2 2 q qe Soe Qe O O D xX D Q Q gt Z Z Fat content Fat content He oO Y Y a 2 Cc C lt lt Reference data Reference data Remember a calibration is the relationship between sensor measurements and fat content across the whole range of possible fat content values for the target fish In graph A where the fish have similar fat content then the custom calibration will only be able to give accurate readings when used on fish in the middle range of fat content When it is used on fish with high or low fat contents i e fish outside the range represented by the sample then it will not be able to give accurate data because it has no data points in those areas 3 4 How many fish make a calibration First and this repeats the point made above if the sample fish do not cover the full range of fat content then you will not get a good calibration If the fish do cover the full range of fat content then you should have a minimum of 10 fish to get a basic calibration To get a good quality calibration you should have at least 30 fish samples Distell Technical note Custom Calibrations Page 4 The more fish samples you can use the more ac
14. tmeter measurements from the drop down list This should normally be RESEARCH 1 1 Locate reference calibration ceo 5 2 3 Enter the reference and analysis data Enter each pair of reference Fatmeter and analysis laboratory data items in the table As the data is entered the best fit graph will gradually build up and you will be able to see visually the spread of data points If you have a large amount of data to enter you may find it easier to create the data table ina spreadsheet then save it as a CSV file This CSV file can then be imported using the Import CSV button The file should be formatted such that the Reference data is in the first column and the Analysis data is in the second You can change the type of best fit curve that is used but normally this is best left as Exponential 5 2 4 Enter the range limits The range limits are the highest and lowest values that your custom calibration can show For example if you are creating a custom calibration for a species that will never have more than 20 fat then you can set 20 0 as the maximum limit Or if your calibration should read up to 50 fat then you can set 50 0 as the maximum Readings outside of this range will be shown as Out of range on the Fatmeter The DMS will automatically set range limits based on the data that you enter but you can override the automatic values 5 2 5 Enter a calibration name The calibration name will appear
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