Abstract
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•Novel structured lipids enriched with capric acid were successfully produced.•NS40086 lipase showed 1, 3 regiospecifity towards microbial oil triacylglycerol.•The activity of NS40086 was higher than that of Lipozyme RM IM at 35 °C and 40 °C.•NS40086 lipase would offer wider applications in lipid synthesis.
Lipids enriched in polyunsaturated fatty acids are very susceptible to oxidation, causing the formation of potentially harmful oxidized products. Hence, it is critical to keep the temperature as low as possible during reaction and storage. In this study, five commercial immobilized lipases were evaluated for their capability to produce novel structured lipids (SLs) enriched with medium-chain fatty acids (MCFAs) through acidolysis of single cell oil (SCO) with capric acid. Among the examined lipases, NS40086 and Lipozyme RM IM showed the highest incorporation degree. The acidolysis reactions resulted in an obvious variation in the fatty acids composition as well as their positional distribution. The obtained SLs contained (33.58 %–34.09 %) capric acid at sn-1, 3 positions with increasing the content of arachidonic acid at the sn-2 position up to (49.82 %–50.25 %). The NS40086 lipase displayed 1, 3 regiospecificity towards the TAG of SCO. The acidolysis reactions using NS40086 lipase resulted in a generation of 23 TAG molecular species containing capric acid. Moreover, the NS40086 lipase was more active than Lipozyme RM IM at relatively low temperatures (35 °C and 40 °C), which could be used effectively as a promising biocatalyst in lipid synthesis.