Effect of frozen storage on fatty acid composition and changes in lipid content of<i>Scomberomorus commersoni</i>and<i>Carcharhinus dussumieri</i>

Abstract

Investigated were the changes in fatty acid composition, oxidation and enzymatic deterioration of lipids in frozen (−30°C) fish fillets from the Persian Gulf. The narrow barred Spanish mackerel (Scomberomorus commersoni) and white cheek shark (Carcharhinus dussumieri) were tested with storage times of 0, 1, 2, 3, 4, 5 and 6 months at −18°C. Statistical results showed that the major fatty acids among the saturated and monounsaturated fatty acids of each fish species were palmitic (C16:0) and oleic (C18:1n-9) acids, respectively. Both linoleic acid (C18:2n-6) and arachidonic acid (AA) (C20:4n-6) were predominant in total n-6 polyunsaturated fatty acids in both mackerel and shark. The EPA (eicosapentaenoic acid; C20:5 n-3) and DHA (docosahexaenoic acid; C22:6 n-3) acids were the major fatty acids among total n-3 acids in both fishes. During frozen storage, the PUFA (40.1 and 23.94%), n-3 (48 and 42.83%), ω3/ω6 (41.36 and 50%), PUFA/SFA (56 and 42.23%) and EPA + DHA/C16 (55.55 and 46.66%) contents decreased in S. commersoni and C. dussumieri, respectively. Also peroxide, thiobarbituric acid (TBA) and free fatty acid (FFA) values significantly increased (P < 0.01) with the time of storage.