A highly efficient immobilized MAS1 lipase for the glycerolysis reaction of n-3 PUFA-rich ethyl esters

Abstract

This study reported that immobilized MAS1 lipase showed high catalytic efficiency in the production of triacylglycerols (TAG) highly enriched with n-3 polyunsaturated fatty acids (PUFA) by glycerolysis of ethyl esters (EE). Immobilized MAS1 lipase was found to have no regiospecificity and be a more suitable catalyst for the glycerolysis of n-3 PUFA-rich EE compared with other enzymes. Higher TAG content (73.9%) and EE conversion (82%) were obtained by immobilized MAS1 lipase than those by Novozym 435 (29.6% and 54.8%, respectively) and Lipozyme RM IM (10% and 49%, respectively). Besides, the effects of temperature, enzyme loading and n-3 PUFA-rich EE/glycerol molar ratio on TAG content were evaluated using response surface methodology. The results showed that temperature, enzyme loading and n-3 PUFA-rich EE/glycerol molar ratio had significant effects on TAG content. The maximum TAG content (76.5%) was achieved under the optimal conditions (enzyme loading of 163.8 U/g substrate, n-3 PUFA-rich EE/glycerol molar ratio of 4.13:1 at 65 °C). Subsequently, the glycerolysis reaction mixtures were further purified by molecular distillation and highly pure n-3 PUFA-rich TAG (96.2%) with similar fatty acids composition to the substrate (EE) was obtained in the final products. In addition, the obtained final products had low acid value and peroxide value (0.03 mg KOH/g and 3.2 meq/kg, respectively). These results indicated that immobilized MAS1 lipase is a promising catalyst for the synthesis of TAG in industrial application.