Synthesis of structured triacylglycerol using microalgae oil and capric acid via a novel 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 a 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 employed as substrates to synthesize the structured TAG. In the first step, n-3 DHA and n-6 DPA were effectively enriched from an initial value of 53% to 86% in the glycerides of microalgae oil via Lipozyme RM IM-catalyzed ethanolysis. The optimum conditions for the ethanolysis were a temperature of 25 ^oC, an enzyme loading of 15%, and a molar ratio of 1:1 (microalgae oil to ethanol). In the second step, capric acid was incorporated into the hydroxy group of the glycerides obtained via ethanolysis to synthesize structured TAG using two different lipases, namely, Lipozyme RM IM and Lipozyme 435. The effects of temperature and vacuum on the TAG conversion were investigated to optimize the lipase-catalyzed esterification. For both lipases, the optimum conditions were a temperature of 60 ^oC and a vacuum of 5 torr. Maximum TAG conversion was achieved with Lipozyme 435, while Lipozyme RM IM exhibited higher regiospecificity toward the sn-1,3 position of TAG.