Enzymatic incorporation of capric acid into a single cell oil rich in docosahexaenoic acid and docosapentaenoic acid and oxidative stability of the resultant structured lipid

Lipase-assisted acidolysis of a single cell oil rich in docosahexaenoic acid (DHA, C22: 6n−3) and docosapentaenoic acid (DPA, C22:5n−6), commerically known as the OMEGA-GOLD oil, with capric acid (CA, C10:0) was carried out. Screening of five commercially available lipases was carried out for oil to CA mole ratio of 1:3 at a temperature of 45 °C, a reaction time of 24 h, 4% (w/w of substrates) PS-30 lipase from Pseudomonas sp. and 2% (w/w of substrates and enzyme) water content. Stereospecific analysis indicated that CA was present mainly in the sn-1,3 positions of the triacylglycerol (TAG) molecules while DHA and DPA were mainly esterified to the sn-2 position. Enzymatically modified oil generally had higher conjugated diene (CD) and 2-thiobarbituric acid (TBA) values than its unmodified counterpart. However, the oil subjected to the same reaction steps in the absence of any enzyme, exhibited a significantly (p<0.05) lower oxidative stability. Therefore, removal or alteration of endogenous antioxidants during the process may be primarily responsible for the compromised stability of the modified oil.