Positional distribution of fatty acids and phospholipid composition in King salmon (Oncorhynchus tshawytscha) head, roe and skin using nuclear magnetic resonance spectroscopy

Abstract

This study used a novel extraction method (ETHEX) to extract the lipid content of King salmon head, skin and roe, and determined the lipid profiles using GC-FID, 13C NMR and 31P NMR spectroscopy. On a wet tissue basis, King salmon roe was found to contain the highest amount of phospholipid (26.53 µmol/g) and n-3 fatty acids (43.32%), followed by head (PL = 10.76 µmol/g; n-3 = 7.21%) and skin (PL = 4.98 µmol/g; n-3 = 8.23%). Total EPA (6.62%) and DHA (28.83%) content, along with the sn-2 positioned EPA (3.25%), DPA (1.36%) and DHA (16.35%) were also higher in roe compared with head and skin. The highest amount of EPA (7.99%) and DHA (34.47%) contents were found in the polar lipid fractions of roe, followed by skin (EPA = 4.19%; DHA = 25.95%) and head (EPA = 2.61%; DHA = 17.85%). This result suggests that salmon roe could be used for developing n-3 phospholipid enriched products.

Keywords: Fatty acids; Fish head; Fish roe; Hexane/ethanol; King salmon; Lipid fraction; NMR spectroscopy; Positional distribution.