POSITIONAL DISTRIBUTION OF OMEGA-3-FATTY-ACIDS IN MARINE LIPID TRIACYLGLYCEROLS BY HIGH-RESOLUTION C-13 NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

The positional distribution [alpha(1,3)-acyl and beta(2)-acyl] of omega 3 fatty acids [18:4(n-3), 20:4(n-3), 20:5(n-3), 22:5(n-3) and 22:6(n-3)] in depot fat of Atlantic salmon (Salmo salar), harp seal oil and cod liver oil triacylglycerols has been examined by C-13 nuclear magnetic resonance (NMR) spectroscopy. The positional distribution data can be defined from the spectrum of the carbonyl (C1 carbon) and the methylene (C2 and glyceryl carbon) regions. In depot fat of Atlantic salmon and cod liver oil, docosahexaenoic acid (DHA) was concentrated in the beta-position of the triacylglycerides with 72.6 and 74.4%, respectively. Only 3.2% of DHA and 4.6% of eicosapentaenoic acid (EPA) were esterified to the beta-position of the triacylglycerides in harp seal oil. EPA is nearly randomly distributed in cod liver oil and muscle lipids of Atlantic salmon, with 37.8 and 39.7%, respectively, in the beta-position. In general, the C-13 NMR-derived data were in accordance with corresponding data reported in the literature obtained by conventional techniques.