Enzymatic modification of evening primrose oil: Incorporation of n-3 polyunsaturated fatty acids

Immobilized lipase SP435 from Candida antarctica was used as a biocatalyst for the modification of the fatty acid composition of evening primrose oil by incorporating n-3 polyunsaturated fatty acid (PUFA) and eicosapentaenoic acid (EPA). Transesterification (ester-ester interchange) was conducted in organic solvent or without solvent, with EPA ethyl ester (EEPA) as the acyl donor. Products were analyzed by gas-liquid chromatography (GLC). After 24-h incubation in hexane, the fatty acid composition of evening primrose oil was markedly changed to contain up to 43% EPA. The amount of 18:2n-6 PUFA was reduced by 32%, and the saturated fatty acid content was also reduced. The effects of incubation time, molar ratio, enzyme load, and reaction medium on mol% EPA incorporation were also studied. Generally, as the incubation time (up to 24 h), molar ratio, and enzyme load increased, EPA incorporation also increased. Evening primrose oil, containing EPA and gamma-linolenic acid (18:3n-6) in the same glycerol backbone, was successfully produced and may be more beneficial for certain applications than unmodified oil.