Characteristics of mackerel mince lipid hydrolysis

The lipid hydrolysis products in minced mackerel stored under vacuum at 2-3 degrees C for 15 days were free fatty acids (FFA) and 1,2-diglycerides (DG); no 1,3-DG or monoglycerides were observed. Lysophosphatidylcholine (LPC and lysophosphatidylethanolamine (LPE) increased and then decreased with time. Lysophosphatidylserine was not observed. More FFA, 1,2-DG, LPC, and LPE were detected in dark muscle than in light muscle. The initial fatty acid composition, by GC, showed no significant differences (alpha - 0.05) among whole, light and dark muscles. When the lipid extracts were separated into three fractions (1: mostly triglycerides; 2: mostly FFA, DG, and cholesterol; and 3: mostly phospholipid), the degree of unsaturation of the lipids in fraction 2 was between those in fraction 1 and 3 and increased with time. These findings support the possibility that fish lipid hydrolysis may affect fish wholesomeness