This note explains why the fish should be kept cold during cold storage and how long different products can be kept. Factors limiting cold storage life are discussed and guidance is given on how to minimize them.
Some brief comments are given on the design and operation of cold rooms, mainly to guide users rather than builders.
Deterioration of fish flesh resulting from the action of enzymes and bacteria can be slowed down by lowering the temperature; when fresh raw materials are properly frozen and kept at a sufficiently low temperature, the deterioration can be almost completely halted. The frozen product deteriorates somewhat during cold storage, but the changes are so small under good conditions that, for the ordinary consumer, the thawed product can no longer be distinguished from the fresh product after several months of storage.
In general, the lower the holding temperature, the longer the storage period; storage temperature is therefore the most important factor affecting the shelf life of frozen fish.
The recommended storage temperature for all frozen seafood products is minus 20 ° F. The bacterial action is completely stopped at this temperature and the undesirable changes in the flesh caused by the enzymes occur only very slowly.
Some products can be safely stored even at high temperatures, provided storage lasts only for short periods. However, since it is not always possible to guarantee that a product stays in the store longer than expected, it is usually safer to use it at less than 20 ° F at all times. Part of the poor quality fish sold to the public has too often been stored at a high temperature.