Preparation of High-purity 1,3-Diacylglycerol Using Performance- enhanced Lipase Immobilized on Nanosized Magnetite Particles

摘要

Early research on the nutritional value of 1,3-diacylglycerols (1,3-DAGs) has resulted in a significant interest in their synthesis. 1,3-DAGs can be produced chemically and biologically. In this work, a regioselective lipase from Rhizopus oryzae was efficiently immobilized on nanosized magnetite particles (NSM) in an oriented way, resulting in significant enhancement of activity. The specific hydrolytic and esterification activities of the immobilized enzyme were 1,660% and 260% of those of the free enzyme, respectively. The immobilized enzyme was then used to catalyze the esterification of oleic acid with glycerol in a solvent-free system for preparation of 1,3-DAG in a 1 L reactor. The catalytic process was studied in detail, the final concentration of 1,3-DAG reached >76% under the optimal condition when the molar ratio of oleic acid to glycerol was 2.8:1. The regioselectivities of free and immobilized enzyme were both >97%. The immobilized enzyme was reused for 55 cycles with only approximate to 30% activity loss at 30 degrees C. The purity of 1,3-DAG was up to approximate to 95% (w/w) after a simple purification step with the recovery ratio approximate to 85%. This is the first report of efficient 1,3-DAG purification by neutralization without acyl migration.