Synthesis of structured lipids using microalgae oil and capric acid via a two-step enzyme reaction

n-3 Docosahexaenoic acid (n-3 DHA) and n-6 docosapentaenoic acid (n-6 DPA) are contained abundantly in microalgae oil. The present study aimed to synthesize structured triacylglycerol (TAG) with n-3 DHA, n-6 DPA, and capric acid via a two-step lipase-catalyzed reaction. Microalgae oil and capric acid were used as substrates to synthesize structured TAG. In the first step, n-3 DHA and n-6 DPA were effectively enriched from an initial value of approximately 53–86 mol% in the glycerides of the microalgae oil obtained via Lipozyme RM IM-catalyzed ethanolysis. The optimum conditions for ethanolysis were a temperature of 25 °C, an enzyme loading of 15 %, and a molar ratio of 1:1 (fatty acid in microalgae oil to ethanol). In the second step, capric acid was incorporated into the hydroxyl group of glycerides obtained through ethanolysis to synthesize structured TAG using two different lipases. The effects of temperature and vacuum on TAG conversion were investigated to optimize lipase-catalyzed esterification. For both lipases, the optimum conditions were a temperature of 60 °C and a vacuum of 5 mmHg. Maximum TAG conversion was achieved with Lipozyme 435, whereas Lipozyme RM IM exhibited higher regiospecificity toward the sn-1,3 positions of TAG.