Biochemical Studies on Oxidative Deterioration of Lipid Profile in Indian Mackerel (Rastrelliger kanagurta)

The present work was aimed to study the oxidative deterioration of lipid profile in Indian mackerel (Rastrelliger kanagurta) at an accelerated storage temperature (40±0.5°C). Fatty acid (FA) composition and oxidative changes were analyzed at regular intervals. Initially, the total polyunsaturated fatty acid (PUFA) content was predominant followed by saturated (SFA) and monounsaturated fatty acids (MUFA). With increase in storage period, the decrease in PUFA content was significantly higher (P < 0.05) than SFA and MUFA. Among the essential FAs, ù-3 FAs were more predominant and with the storage period they showed a decreasing trend whereas the lipid oxidation products viz., peroxides, malonaldehyde and free fatty acids (FFA) increased significantly. The decrease (P < 0.05) in PUFA compounds (82.5%) has been as follows: ù-3 (91%), ù-3/ù-6 ratio (66.65%), PUFA/SFA ratio (66.3%) and Polyene index (PI) (82.24%) at the end of storage period. In addition, the peroxides and malonaldehyde contents showed a negative correlation (r² = 0.98 and 0.96 respectively) with PUFA and FFA showed a negative correlation (r² = 0.98) with phospholipids indicating the overall loss of valuable lipid fractions with the storage period. The study provides strong evidence that, oxidation of lipid affects nutritional quality of mackerel.