ENZYMATIC-SYNTHESIS OF GLYCERIDES FROM DHA-ENRICHED PUFA ETHYL-ESTER BY GLYCEROLYSIS UNDER VACUUM

Pseudomonas lipase immobilized on CaCO3 powder was used for the glycer olysis of n - 3 polyunsaturated fatty acid ethyl esters to prepare nut ritionally valuable glycerides. The initial ethyl ester contained 65 o r 99% docosahexaenoic acid ethyl ester (DHAEE) which is very unstable and readily oxidized. The process performance was intensified by: (1) using Pseudomonas lipase which has good specificity for docosahexaenoi c acid (DHA), (2) shifting the reaction equilibrium by evaporation of the resulted ethanol under vacuum and (3) enhancing the enzyme operati onal stability by immobilization on CaCO3 powder. Under these conditio ns, over 90% conversion of DHAEE was achieved in 5 h and the oxidative deterioration of DHA was avoided. The final product contained 53% par tial glyceride and, thus, had good emulsifying power. The catalyst was reused 5 times showing a very good stability in this system. Other li pases were tried for this reaction and different glyceride composition s were obtained depending on the enzyme specificity for the 1(3)-posit ion of glycerol. (C) 1998 Elsevier Science B.V. All rights reserved.