Enrichment of salmon oil with n-3 PUFA by lipolysis, filtration and enzymatic re-esterification

Selective enzymatic hydrolysis of salmon oil extracted without solvent from by-products was carried out under mild conditions, using a stereospecific sn-1, sn-3 lipase Novozyme®. A modification of the lipid class composition was obtained by controlling the degree of hydrolysis (40%, 24 h). The mixture of acylglycerols and free fatty acids was submitted to a filtration step to retain in the retentate most of the saturated fatty acids, with melting peaks ranging from -31.9 °C to +14.7 °C obtained by differential scanning calorimetry. This step allowed a significant increase of polyunsaturated fatty acids (PUFA) from 39.2 mol-% in the crude oil to 43.3% in the permeate. The remaining free fatty acids in the permeate (20.2 wt-%) was re-esterified with an immobilized 1, 3-specific lipase IM60. Acylglycerols synthesis reached 90% in optimized conditions. After 48 h of reaction, the distribution of monoacylglycerols, diacylglycerols and triacylglycerols was 22.1, 28.7, 43.4 (w/w), respectively. The re-esterification step did not modify the PUFA content obtained after membrane filtration.