Synthesis of α-linolenic acid-rich triacylglycerol using a newly prepared immobilized lipase

An α-linolenic acid (ALA)-rich triacylglycerol (TAG) was synthesized from an ALA-rich fatty acid (FA) from perilla oil and glycerol, using a newly prepared immobilized lipase under vacuum. The ALA-rich FA (purity >90 wt%) used as the substrate was prepared by urea complexation from perilla oil FAs. Liquid Lipozyme TL 100 L lipase from Thermomyces lanuginosus was used for immobilization. Nine different hydrophilic and hydrophobic carriers for immobilization were tested, and Duolite A568, which is a hydrophilic resin, was selected as the best carrier. This immobilized lipase was used to synthesize TAG by direct esterification under vacuum. The parameters investigated were temperature, enzyme loading, and vacuum level. The optimum reaction conditions were a temperature of 60 °C, an enzyme loading of 15% (based on the total weight of the substrate), and a vacuum of 0.7 kPa, respectively. The maximum conversion to TAG of ca. 88 wt% was obtained in 12 h under the optimum conditions.