This paper for the first time presents the production of diacylglycerol (DAG) by hydrolysis of high-melting oil by a highly thermostable lipase (T1 lipase). T1 lipase was expressed in recombinant Escherichia coli, and used to produce DAG by catalyzing the hydrolysis of palm stearin. The optimal conditions were obtained by a water content of 30% w/w (with respect to oil mass), T1 lipase at a concentration of 7.5 U/g (U/w, with respect to oil mass) and at 60°C. Scale-up reaction was attempted based on the optimized conditions and 28.1% of DAG was achieved. Molecular distillation was employed for purification of DAG from the reaction mixture and the final DAG product yielded 42.5% of DAG (27.8% for 1,3-DAG and 14.7% for 1,2-DAG) and 57.5% of triacylglycerol (TAG). During hydrolysis, T1 lipase was discovered to show 1,3-regiospecific activity toward TAGs. The results indicated that T1 lipase is a prospective enzyme which can be used in the modification of high-melting oils and fats.
Practical applications: Enzymatic modification of high-melting oils is a challenging task. Here DAG production by T1 lipase-catalyzed hydrolysis of palm stearin (PS) is reported for the first time.