Selective concentration of EPA and DHA using Thermomyces lanuginosus lipase is due to fatty acid selectivity and not regioselectivity

The selectivity of anchovy oil hydrolysis was optimised for Thermomyces lanuginosus lipase, so that docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were concentrated and partially separated from each other. Enzyme concentration and pH control were important factors for effective hydrolysis. Monitoring percent hydrolysis using capillary chromatography with flame ionisation detector (Iatroscan) and fatty acid selectivity using gas chromatography (GC) indicated that during hydrolysis DHA primarily remained on the glycerol backbone, while EPA was progressively removed. 13C nuclear magnetic resonance (NMR) data showed that selectivity of hydrolysis was primarily due to fatty acid selectivity and not regioselectivity, with hydrolysis from both sn-1,3 and sn-2 sites being equally favoured.