Fish deterioration due to protein denaturation, changes in fat and dehydration can be slowed down by lowering the storage temperature. Frozen fish products should be stored at a temperature appropriate to the type, type of product and the expected shelf life.
The recommended storage temperature for all fishery products is -30 ° C, and this temperature has also been accepted throughout Europe. Changes under the action of bacteria, in any practical sense, cease completely at this temperature, and the rate at which other undesirable changes occur is greatly reduced. Some products can be safely stored at a temperature above the recommended temperature of -30 ° C, provided that they are stored for a short time. Since it is not always possible to guarantee that the product will not be stored in the warehouse longer than expected, it is usually safer to use the recommended lower temperature.
Cold store operators can rarely guarantee that they only store one type or type of fish, or store it for a limited period of time. Refrigerators built for fish storage should preferably operate at -30 ° C, but at a higher temperature, if circumstances allow and appropriate standards or recommendations.
A leading refrigeration design engineer estimated that under certain conditions, the total operating costs in a refrigeration chamber at -30 ° C are only 4% higher than when operating at -20 ° C. Costs will be higher.
The difference between the total cost and the operating or running costs will be clearly explained to the reader by examining the cost of the cold store, described in detail in Chapter 10. The total cost is the most realistic measure that can be used when comparing. Table 16 shows that preserving fish at -30 ° C has a significant advantage in terms of shelf life. It is possible that the advantage of improved quality may largely offset additional storage costs at lower temperatures. These times correspond to a practical shelf life, defined as the time during which the product remains suitable for consumption or the desired process.