Consequences of frozen storage for nutritional value of hake

Differences between fresh and frozen hake muscle in which proteins were highly aggregated during frozen storage, and their relationship with nutritional quality are evaluated. The differences between fresh and frozen muscle proteins were studied on the basis of protein solubility, type and state of muscle aggregation and amino acid composition. Nutritional value was determined by nitrogen balance and amino acid composition in the blood. The high level of aggregation in the frozen muscle was due mainly to disulfide and other covalent bonds. Lysine diminished in frozen muscle and in plasma. Although in frozen fish muscle, proteins were highly aggregated even by disulfide and non-disulfide covalent bonds, nitrogen balance in fresh and frozen fish was similar.