The Fish Freshness Meter “Torrymeter” is used around the world as an objective method of measurement of the relative freshness of most fish species caught, processed and sold around the world.
Also, the meter is exceptionally useful for identifying fish that have been previously frozen by displaying a value of “4 or less” – even although the fish looks very fresh and wholesome.
Each country has a number of “Taste Panels”, whose job it is to create standards for the quality of fish caught and processed in their own region. The quality of fish landed and processed is then adjudged using the “Taste Panel” standards as a base for comparison. Distell has created Organoleptic Charts for most species in European waters. A set of these is included in APPENDIX 1, starting on page 45. If this does not include the fish species you intend to measure, it is quite easy to prepare your own Chart as below:
Firstly…The Criteria you wish to list. Decide on the information that you wish to be included in your Chart. For instance, Distell’s charts contain the following information:
- Raw odour description, normally available from taste panels in your country
- Cooked flavour description, normally available from taste panels in your country
- Taste panel scores, which illustrate a value for freshness
- Relative age of the fish, based upon taste panel scores, and equivalent to the “Number of Days in Ice at 0o C, but not allowed to freeze”.
- EC Grading standards as agreed by the European Community, again adjudged by reference to “taste panel scores”
- An indication of the state of freshness.
- And finally, the value shown by the Freshness Meter, calibrated to compare against other criteria listed above.
Secondly…Preparation of the chart. Obtain samples of the fish for which you wish to create a chart. Ensure that you know the age of the fish from the moment of catch / death. Ensure that you know that the fish has been handled and stored under optimum conditions.
- Procure 1 or 2 fish from the local market or, better still, fish freshly caught at sea.
- Immediately store the fish in ice / water mix, and maintain at or just above 0° C. Do not allow the fish to become frozen as this destroys the cellular structure. The meter will display a value of “4 or less”, where fish have been allowed to freeze.
- Measure the fish as recommended in the Handbook, ensuring that you measure consistently at the same position on the fish each time.
- Measure the fish twice per day, in the morning and in the evening and keep a note of the readings.
- Continue the process until the fish is spoiled.
Using this information prepare your Freshness Chart and, if possible, have your new
Freshness Chart checked by an experienced fisherman or fish expert who can help to
validate your results and help you set the values against other measures of freshness.
When finished, your Freshness Chart should resemble the organoleptic charts shown in User Manual.