The Effects of Freezing on the Nutritional Composition of Fish

The degradation of fish in the storage condition of the freezer is influenced by several factors which include the fishing species, the rate at which the fish is frozen, the temperature at which it is stored, the duration of storage, the type of freezing applied, and enzymatic processes. The freezing and frozen storage lead to macro- and microscale changes of fish muscles, with major changes being lipid oxidation inducing rancidity, protein denaturation and aggregation causing toughness, red color fading and freezer burn. The process of freezing involves transforming water to ice which in turn results into an increase in the concentration of dissolved substances, adjusting the acid-base balance. It can lead to pH changes of up to 1 unit, often towards acidity and in some cases up to 10 units due to salt and other compounds precipitation. The described changes permanently alter the properties of the physical-chemical nature of frozen fish including the convenience and storage conditions of the food, thereby directing attention to the necessity of new approaches in technologies. Keywords: Frozen storage, fish degradation, nutritional composition, enzymatic processes, freezing effects.