STRUCTURED LIPIDS: ACIDOLYSIS OF GAMMA‐LINOLENIC ACID‐RICH OILS WITH n‐3 POLYUNSATURATED FATTY ACIDS

Structured lipids were synthesized by acidolysis of γ‐linolenic acid‐rich oils and n‐3 polyunsaturated fatty acids (PUFA), namely eicosapentaenoic acid (EPA; 20:5n‐3) and docosahexaenoic acid (DHA, 22:6n‐3), using different lipases. Lipase PS‐30 from Pseudomonas sp. was chosen over the other enzymes to catalyze the acidolysis reaction owing to higher incorporation of n‐3 PUFA. Effects of mole ratio, reaction time, incubation temperature, enzyme load, and solvent type on acidolysis reactions were studied. At 250 enzyme activity units, incorporation of n‐3 PUFA reached optimal values of 29.9 and 30.7% for the reactions with borage and evening primrose oils, respectively. For the time course reaction, incorporation of n‐3 PUFA increased up to 34.1 and 31.5% (in 30 h), in borage and evening primrose oils, respectively. After 24 h incubation in hexane, n‐3 PUFA (EPA+DHA) incorporated into borage and evening primrose oils was 31.8 and 32.7%, respectively. The highest n‐3 PUFA incorporation in both oils occurred at a mole ratio of 1:2:2 (oil/EPA/DHA). Among the solvents tested, n‐hexane was found to be highly effective; total n‐3 PUFA incorporation of 33.3 and 27.8% in borage and evening primrose oils, respectively, was achieved in hexane. However, the solvent‐free reaction afforded products with a total of 23.4–28.8% n‐3 fatty acids (EPA and DHA).