Hydrolysis of soybean oil to produce diacylglycerol by a lipase from Rhizopus oryzae

A lipase from Rhizopus oryzae (rProROL) was produced by recombinant Pichia pastoris in high productivity with a maximum lipase activity of 15,900 U/mL, and was employed to hydrolyze soybean oil for the production of diacylglycerol (DAG). Changes in triacylglycerol (TAG) conversion and DAG content were observed under various factors, like pH, water content, temperature and enzyme loading. A polynomial equation (R-2=0.9797) between DAG content and TAG conversion was modeled and showed good agreement with the experimental results. The highest content of DAG at 32.09% was observed when TAG conversion was between 68% and 73%. Besides, C-13 nuclear magnetic resonance (NMR) was used to identify the 1,2(2,3)-DAG and 1,3-DAG, and during hydrolysis, rProROL was discovered to show 1,3-regioselectivity in the hydrolysis. Moreover, rProROL exhibited high hydrolytic activity and capacity in the accumulation of DAG, indicating that rProROL is a prospective enzyme which could be used in the oils and fats industries. (C) 2015 Elsevier B.V. All rights reserved.