The acyl migration in the production of 1,3-diacylglycerol (1,3-DAG) by immobilized lipozyme RM IM-catalyzed esterification reaction in a solvent-free system was investigated, particularly including the acyl migration of 1,3-DAG to 1,2-diacylglycerol (1,2-DAG), which affected by some of the system's parameters (substrate molar ratio, enzyme load and reaction temperature). The results showed that all parameters had strong positive influences on acyl migration. With the increasing substrate molar

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... ratio of oleic acid to glycerol from 1:1 to 3:1, the acyl migration showed a decreasing-increasing pattern. However, the degree of acyl migration increased gradually concomitant with the increasing of enzyme load (2 _ 10 wt% of substrates) and reaction temperature ( 45 _ 75℃). The conditions for the highest yields of 1,3-DAG and the relatively low levels of acyl migration were optimized as follows: temperature 65℃, oleic acid/glycerol molar ratio 2:1, enzyme load 6%, reaction time 2 h, 0.01 MPa vacuum, 200 rpm stirring speed.