Lipid damage during frozen storage of whole jack mackerel (Trachurus symmetricus murphyi)

The damage on the lipid fraction of whole jack mackerel (Trachurus symmetricus murphyi, Carangidae) during 120 days of frozen storage was studied. The chemical composition was determined through proximate analysis. Lipid quality deterioration was evaluated by measuring free fatty acids, peroxide values, conjugated dienes and p-anisidine values. Also, the total volatile base-nitrogen value was determined to check the bacterial activity during frozen storage. The results showed that jack mackerel is a medium-fat fish species with 74-78% moisture, 3-5% fat (crude) with 20-27% polyunsaturated fatty acids (PUFA). The lipid hydrolysis was the major damage during frozen storage, with a correlation coefficient of 0.96 after 75 days of storage. The normal oxidative rancidity (primary and secondary products) present in fillets of different species was not observed in the whole fish. The autolytic changes were predominant, because bacterial activity was low during the entire storage time.