Fisheries Global Information System, 2006
Many different techniques have been used to preserve fish quality and to increase their shelf life. They are designed to inhibit or reduce the metabolic changes that lead to fish spoilage by controlling specific parameters of the fish and/or its environment. These techniques can be classified as outlined below.
Generally, they encompass a wide array of technologies used to decrease the fish temperature to levels where metabolic activities – catalyzed by autolytic or microbial enzymes – are reduced or completely stopped. This is possible by refrigeration or freezing where the fish temperature is reduced, respectively, to approximately 0 °C or less than – 18°C.
Fish refrigeration can use cool air circulating around the fish (mechanical refrigeration) or icing. Fish icing and boxing on-board fishing vessels is not always possible in the case of small pelagic that are caught in large quantities. These are chilled using refrigerated seawater (RSW) or chilled seawater (CSW). Chilled or frozen fish products require additional cooling in cold store to avoid an increase in temperature. The design (size, insulation, palletization) and management of cold stores are key for fish quality and energy saving. A major environmental issue relates to the development of alternative refrigerants to replace the chlorofluorocarbons (CFCs) which are damaging to ozone layers.