Lipase-catalyzed esterification of glycerol and polyunsaturated fatty acids from fish and microalgae oils

This paper reports on the synthesis of triglycerides by enzymatic esterific ation of polyunsaturated fatty acids (PUFA) with glycerol. The lipase Novoz ym 435 (Novo Nordisk, A/S) from Candida antarctica was used to catalyze thi s reaction. The main factors influencing the degree of esterification and t riglyceride yield were the amount of enzyme, water content, temperature and glycerol/fatty acid ratio. The optimum reaction conditions were establishe d as: 100 mg of lipase; 9 mi hexane; 50 degrees C; glycerol/PUFA concentrat e molar ratio 1.2:3; 0% initial water; 1 g molecular sieves added at the st art of reaction; and an agitation rate of 200 rpm. Under these conditions, a triglyceride yield of 93.5% was obtained from cod liver oil PUFA concentr ate; the product contained 25.7% eicosapentaenoic acid and 44.7% docosahexa enoic acid. These optimized conditions were used to study esterification fr om a PUFA concentrate of the microalgae Phaeodactylum tricornutum and Porph yridium cruentum. With the first, a triglyceride yield of 96.5%, without mo noglycerides and very few diglycerides, was obtained after 72 h of reaction ; the resulting triglycerides had 42.5% eicosapentaenoic acid. A. triglycer ide yield of 89.3% was obtained from a P. cruentum PUFA concentrate at 96 h of reaction, which contained 43.4% arachidonic acid and 45.6% EPA. These h igh triglyceride yields were also achieved when the esterification reaction was scaled up 5-fold. (C) 1999 Published by Elsevier Science B.V. All righ ts reserved.