One-pot enzymatic synthesis of docosahexaenoic acid-rich triacylglycerols at the sn-1(3) position using by-product from selective hydrolysis of tuna oil

Docosahexaenoic acid (DHA)-rich oil has been industrially produced by selective hydrolysis of tuna oil with a lipase that acts weakly on DHA. The free fatty acids (FFAs) generated in this process as by-products contain a high DHA concentration (46 wt%) but are treated as industrial waste. This study attempted to reuse these by-product FFAs using a one-pot process, and succeeded in producing triacylglycerols (TAGs) through the esterification of the by-product FFAs with glycerol using immobilized Rhizomucor miehei lipase. Regiospecific analysis of the resulting TAGs showed that the content of DHA at the sn-1(3) position (51.7 mol%) was higher than the content of DHA at the sn-2 position (17.3 mol%). The DHA distribution in TAGs synthesized in this study was similar to the DHA distribution in TAGs from seal oil.