Enrichment of stearidonic acid from echium oil via a two-step lipase-catalyzed esterification

Stearidonic acid (SDA) from echium oil was enriched substantially by a two-step lipase-catalyzed esterification using Lipase OF from Candida rugosa and Lipozyme RM IM from Rhizomucor miehei. During the first step, SDA was enriched in the fatty acid fraction via C. rugosa lipase-catalyzed esterification with lauryl alcohol. The optimum reaction conditions of water content, temperature, and enzyme loading were 0.25%, 30°C, and 2%, respectively, in terms of the content and yield of SDA. Under these conditions, SDA content was increased to 39.3 from 14.3% of the starting material. To further elevate SDA content, Lipozyme RM IM-catalyzed esterification was then conducted using the SDA enriched fatty acid from the first step and a maximum SDA content of 54.1% was obtained. Using this two-step lipase-catalyzed esterification, SDA content increased fourfold from 14.3 to 54.1% with a 74.8% yield. γ-Linolenic acid (GLA) was also enriched together with SDA. Practical applications: SDA, which is one of ω-3 fatty acids, is considered as a source of health beneficial polyunsaturated fatty acids for vegetarians. SDA enrichment obtained in this study leads also to a high level of GLA. Therefore, this enrichment can be applied to produce a novel structured lipid containing a significant amount of SDA and GLA.