Differentiation of Fish Oils According to Species by C-13-NMR Regiospecific Analyses of Triacyglycerols

The aim of this study was to use C-13-nuclear magnetic resonance (NMR) regiospecific analyses of triacylglycerols to distinguish fish oils from different fish species for authentication purposes. C-13-NMR data of muscle lipids from Atlantic salmon (Salmo salar L.), mackerel (Scomber scombrus) and herring (Clupea harengus) were obtained, and the distribution of omega-3 polyunsaturated fatty acids between the sn-1,3 and sn-2 glycerol chains calculated from the carbonyl region. The results show that there were significant differences in the sn-2 position specificity of the fatty acids 22:6n-3, 20:5n-3 and 18:4n-3 among the species investigated. The most pronounced difference was that herring had a higher proportion of its 22:6n-3 in the sn-2 position compared to the two other species. Principal component analysis of data points in the carbonyl-region showed that there were also differences in the level and regiospecific distribution of monounsaturated/saturated fatty acids, which made it possible to distinguish oils of these three species solely from the carbonyl region of C-13-NMR spectra.