γ‐Linolenic acid‐rich triacylglycerols derived from borage oil via lipase‐catalyzed reactions

Abstract γ‐Linolenic acid (GLA), a precursor of arachidonic acid, possesses physiological functions of modulating immune and inflammatory response. Highly purified GLA is desired both as a medicine and as an ingredient of cosmetics. In this work, urea fractionation and lipase‐catalyzed reactions were employed for the enrichment of GLA in borage oil. GLA content in free fatty acids from saponified borage oil can be increased from 23.6 to 94% by the method of urea fractionation. Partial hydrolysis of borage oil catalyzed by immobilized Candida rugosa lipase raises GLA content in the unhydrolyzed acylglycerols from 23.6 to 52.1%. The IM‐60 catalyzed acidolysis reaction between the GLA‐rich free fatty acid and the unhydrolyzed acylglycerols increases the GLA content in the acylglycerols from 52.1 to 75%. The acylglycerols in the reaction product contains ca. 90% triacylglycerol. The effects of temperature, water content, substrate weight ratio, and organic solvents on the GLA content in the acylglycerols were examined.