Concentration of n-3 polyunsaturated fatty acid glycerides by Candida antarctica lipase A-catalyzed selective methanolysis

Abstract

n-3 polyunsaturated fatty acids (n-3 PUFA) have biologically important functions in human beings, but their contents in natural oils are usually low. This study investigated the concentration of n-3 PUFA-enriched glycerides by Candida antarctica lipase A (CAL-A)-catalyzed selective methanolysis of algal oil. First, lipases and acyl acceptors were screened. Subsequently, the methanolysis conditions including methanol concentration in aqueous solution, molar ratio of methanol to oil, reaction temperature, lipase loading and reaction time, were optimized. The results indicated that CAL-A could effectively identify n-3 PUFA during methanolysis. Saturated fatty acids and monounsaturated fatty acids were released from algal oil by CAL-A-catalyzed methanolysis, causing the production of n-3 PUFA-enriched glycerides. Under optimal conditions (3:1 of molar ratio of methanol to algal oil, 20% methanol aqueous solution, 6% CAL-A dosage, 25 °C, 18 h), the n-3 PUFA content increased from the initial 45.96% to 73.96%, with an n-3 PUFA yield of 81.76%. The reusability of CAL-A demonstrated that under optimal conditions the lipase could be used for 8 times. Therefore, this enzymatic process is efficient for synthesis of n-3 PUFA-enriched glycerides.