Analysis of lipids extracted from salmon (Salmo salar) heads by commercial proteolytic enzymes

Fresh salmon heads were submitted to controlled proteolysis using food-grade commercial enzymes (Alcalase((R)), Neutrase((R)) and Protamex (TM)). The release of oil under mild conditions (60 degrees, 2 h) compared favourably with organic solvent extraction (19.8% vs. 21.5%). Lipids extracted by solvent and lipids resulting from enzymatic processes displayed a similar content of PUFA (about 35%), mainly eicosapentaenoic acid (EPA; 8.4% vs. 7.7%) and docosahexaenoic acid (DHA; 12.1% vs. 11.9%). Thin-layer chromatography (TLC-FID latroscan) showed that the polar lipid fraction accounted for 55% of total lipids (phosphatidylethanolamine, 20.7%; phosphatidylcholine, 14.8%). Salmon head phospholipids may be more effective carriers of highly unsaturated fatty acids to specific tissues than triacylglycerols, as shown by their content in EPA (10.3 and 6.9%, respectively) and DHA (33.1 and 9.1%, respectively).