TRANSESTERIFICATION OF SOY LECITHIN BY LIPASE AND PHOSPHOLIPASE

Soy lecithin was modified by enzymatic transesterification in a solven t-free system. 1,3-Specific Rhizomucor miehei lipase was found to be e fficient in the transesterification with lauric acid and oleic acid, w here oleic acid was more incorporated into soy lecithin. Phospholipase A(2) incorporated lauric acid hardly at all, but it hydrolyzed lecith in efficiently. The mixture of lipase and phospholipase A(2) (1:1, W/W ) incorporated lauric acid to the same extent as did 1,3-specific lipa se alone at the same total enzyme concentration. The main fatty acids replaced were palmitic and linoleic acids by 1,3-specific lipase and i ts mixture with phospholipase AZ, and linoleic and linolenic acids by phospholipase A(2) alone, suggesting an improved oxidative stability o f the resulting product. Hydrolysis could not be prevented, but it cou ld be regulated by incubation time and by enzyme dosage. The minimal w ater content for significant incorporation of lauric acid into lecithi n was below 0.5% of the weight of the reaction mixture.