Question
What precautions should I take when comparing Fish Fatmeter results with laboratory Analysis?
Answer
This is a very important question, and great care should be taken to ensure rigorous attention to detail... . Where you know that the measurements made by the Fatmeter are going to be compared to some form of Laboratory Analysis, always ensure a rigorous preparation procedure. Otherwise you may get a different result from the laboratory, and this will create confusion and doubt.
The preparation instructions are clearly described in the Fatmeter Handbook, but for the avoidance of doubt we have given a brief description here, as follows...
Switch ON the Fatmeter and allow it to warm up and stabilise for 10 minutes. Then select the correct calibration, from the menu. You can confirm that it is the correct calibration by pressing the 'RESET' button on the Fatmeter... the selection will be displayed briefly on the LCD display.
You are now ready to take measurements... The Fatmeter will request a series of EIGHT readings. Please ensure that the readings are taken from around the sample... at recommended measurement sites, fully described in your handbook.
Place the sensor head fully in contact with the sample, being careful to exclude any air cavities. Press and hold the 'READ' button until the reading has stabilised, then release the button, whilst sensor is still firmly in contact with the sample.
Take all eight readings from various positions on the sample ( see chart supplied ). After the eight readings the Fatmeter will automatically display the Average Fat Content of the sample. The result should give accurate Fat Content, representing the Fat / Oil Content of the sample.
For the avoidance of doubt... Calibrations have been created to represent different portions of the fish. For instance... The following THREE Calibrations represent different portions of a Salmon...
| SALMON-1 |
Measurements taken along the length of the fish, BOTH sides. After 8 readings the readout shows the average fat / oil content representing Fat Content of... TWO x TRIMMED FILLETS of this one fish (subject to 'Standard trimming techniques' that is…excluding head, tail, fins, skin, belly cavity, and fat deposits at Dorsal and Anal Fins) |
| SALMON-2 |
Measurements taken on the 'Mowi Section' of the fish. After 8 readings the readout shows the average fat / oil content representing the 'Mowi Section' of this one fish (subject to 'Mowi Standard trimming techniques'... please see appendix section for further details). |
| SALMON-3 |
Measurements taken on the 'NQC Section' of the fish. After 8 readings the readout shows the average fat / oil content representing fat Content of the 'NQC Section' of this one fish (subject to 'NQC Standard trimming techniques'... please see appendix for further details. |
Having measured the sample with the Fatmeter, duly prepared samples should now be sent to the Laboratory for analysis, if you wish to confirm the performance of the Fatmeter. Remember, the laboratory only use between 9 – 25 gms of the fish sample for the analysis process, so you must ensure that the laboratory do in fact blend ALL of the fish sample... prior to taking their sample for analysis.
In addition, the laboratory must do triplicate analysis, taking a 2nd & 3rd sample from the blended sample. This ensures that we have a check on the uniformity of the blended product.
The Fatmeter can be compared with any recognised Lab Method. However, the Fatmeter has been calibrated against Foss-Let Chemical Method... an AOAC recognised Laboratory based Chemical Extraction Method. This will give the best comparative accuracy. There can be significant variances in Laboratory results depending on the method used, and we recommend that the method of comparison is taken into account. If you have followed carefully the instructions above, the Fatmeter results should compare favourably with laboratory results, and should be within the performance range quoted in Operators Manual.
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