Enzymatic Synthesis of Extremely Pure Triacylglycerols Enriched in Conjugated Linoleic Acids

摘要

This work was objectively targeted to synthesize extremely pure triacylglycerols (TAG) enriched in conjugated linoleic acids (CLAs) for medical and dietetic purposes. Extremely pure CLA-enriched TAG was successfully synthesized by using the multi-step process: TAG was primarily synthesized by lipase-catalyzed esterification of CLA and glycerol and then the lower glycerides [monoacylglycerol (MAG) and diacylglycerol (DAG)] in the esterification mixtures was hydrolyzed to free fatty acids (FFAs) by a monoand di-acylglycerol lipase (lipase SMG1), finally, the FFAs were further separated from TAG by low temperature (150 °C) molecular distillation. The operation parameters for the lipase SMG1-catalyzed hydrolysis were optimized using response surface methodology based on the central composite rotatable design (CCRD). The operation parameters included water content, pH and reaction temperature and all of these three parameters showed significant effects on the hydrolysis of lower glycerides. The optimal conditions were obtained with a water content of 66.4% (w/w, with respect to oil mass), pH at 5.7 and 1 h of reaction time at 19.6 °C. Under these conditions, the content of lower glycerides in the reaction mixture decreased from 45.2% to 0.3% and the purity of CLA-enriched TAG reached 99.7%. Further purification of TAG was accomplished by molecular distillation and the final CLA-enriched TAG product yielded 99.8% of TAG. These extremely pure CLA-enriched TAG would be used for in vivo studies in animals and humans in order to get specific information concerning CLA metabolism.