Lipase catalyzed modification of fish oil to incorporate capric acid

Immobilized lipase, IM60, from Rhizomucor miehei, was used as a biocatalyst for the incorporation of capric acid (C10:0) into menhaden fish oil concen trate containing 34.7 mol% eicosapentaenoic acid (20:5n-3) and 34.4 mol% do cosahexaenoic acid (22:6n-3). Transesterification (acidolysis) was performe d in hexane and solvent-free media. Tocopherol content was analyzed before and after enzymatic modification. Products were analyzed by gas liquid chro matography. After 24 h incubation in hexane, there was an average of 31.1+/ -4.6 mol% incorporation of C10:0 into fish oil, while 20:5 and 22:6 were re duced to 12.6+/-3.1 and 13.7+/-4.4, respectively. The solvent-free reaction produced an average of 28.8+/-4.7 mol% capric acid incorporation; 20:5 and 22:6 decreased to 16.1+/-5.7 and 13.5+/-3.0 mol%. The effect of incubation time, substrate mole ratio, enzyme load, and added water were also studied . Generally, as enzyme load, mole ratio, and incubation time increased, mol % capric acid incorporation also increased. Time course of reaction indicat ed that the highest C10:0 incorporation occurred at 72 h, for both the reac tion in hexane (33.5 mol%) and the solvent-free reaction (36.0 mol%). The h ighest C10:0 incorporation for the substrate mole ratio reaction occurred a t a mole ratio of 1:8 in hexane (50.7 mol%) and the solvent-free reaction ( 36.7 mol%). Although the highest C10:0 incorporation (31.8 and 48.6 mol%) o ccurred at an enzyme load of 15% in hexane and 20% for the solvent-free rea ction respectively, the values were not significantly different (P < 0.05) after 5% enzyme load. Mol% incorporation of C10:0 declined with increasing amounts of water. At 1% added water, high C10:0 incorporation was achieved for the reaction in hexane (39.3 mol%) and the solvent-free reaction (26.0 mol%). Pancreatic lipase catalyzed sn-2 positional analysis was performed o n the fish oil before and after enzymatic modification. Fish oil containing capric acid was successfully produced and may be beneficial in certain foo d and nutritional applications. (C) 2001 Elsevier Science Ltd. All rights r eserved.