Preparation of γ-linolenic acid rich triacylglycerol from borage oil via a two-step lipase-catalyzed reaction

γ-Linolenic acid (GLA) rich triacylglycerol (TAG) was successfully synthesized from glyceride, instead of glycerol, and fatty acid (FA) via Lipozyme TL IM-catalyzed esterification as a novel strategy. In the first step, GLA was enriched into glyceride fraction from borage oil by Candida rugosa lipase-catalyzed hydrolysis. The glyceride was separated from the reaction mixture by molecular distillation. GLA was enriched from 20.64% in borage oil to 45.94% in the glyceride fraction under optimum conditions. In the second step, the Lipozyme TL IM-catalyzed synthesis of TAG was carried out with the glyceride, and the FA obtained by saponification of a portion of the glyceride. The optimum conditions were the temperature of 50°C, the enzyme loading of 10%, and the vacuum level of 20 mmHg, respectively. The maximum TAG content of approximately 92% was achieved after 12 h under the optimum conditions.