Degradation of fish due to protein denaturation, fat changes and dehydration can be slowed down by lower storage temperature. Frozen fish products must be stored at temperatures appropriate to the species, product type and expected shelf life.
The recommended storage temperature for all fishery products is -30 ° C and this temperature has been adopted throughout Europe. Changes with bacterial action, in any practical sense, are completely interrupted at this temperature and the rate at which other undesirable changes occur is significantly reduced. Some products can be stored safely at temperatures above the recommended temperature of -30 ° C, provided they are stored for a short time. Because it is not always possible to ensure that a product will not remain in excess of what is expected, it is usually safer to use the recommended lower temperature.
Cold walkers can rarely ensure that they store only one species or type of fish or keep it for a limited time. Cold rooms built for fish storage should preferably be able to operate at -30 ° C but at a higher temperature if the circumstances and the relevant codes or recommendations allow.
The overriding principle in the design of refrigeration chambers estimates that, under certain conditions, the total operating cost of a cold room at -30 ° C is only 4% higher than that of an operation at -20 ° C. the cost will be higher.
The difference between total cost and operating or business costs will be clearly explained to the reader by looking at the cost of the cold store detailed in Chapter 10. Total cost is the most realistic element to use when making comparisons. Table 16 shows that keeping fish at -30 ° C has a significant lifetime advantage. It is likely that the advantage of improved quality can greatly offset the extra cost of storage at a lower temperature. These times correspond to the practical shelf life, defined as the time the product remains fit for consumption or for the desired procedure.