Two-Step Enzymatic Synthesis of Structured Triacylglycerols from ARASCO© and Coconut Oil

Triacylglycerols containing medium-chain fatty acids at the sn-1,3 positions and a long-chain fatty acid at the sn-2 position (MLM-TAG) are of nutritional interest. However, they are scarce in common food sources and are usually synthesized by chemical or enzymatic methods. In this work, the enzymatic synthesis of MLM-TAG was attempted using sn-2 monoacylglycerols (sn-2 MAG) from the ethanolysis of an arachidonic acid-rich fraction from ARASCO and fatty acid ethyl esters from the ethanolysis of coconut oil as substrates. The highest yield of sn-2 MAG (23.3 mol%) was obtained after 1 h of ethanolysis with Novozym 435 lipase at 25 °C, and the best profile of the ethanolysis products of coconut oil was obtained after 24 h of reaction catalyzed by the lipase from Thermomyces lanuginosus. Regarding the enzymatic synthesis of structured TAG, the lipase from Rhizopus oryzae gave better results than those from Thermomyces lanuginosus and Rhizomucor miehei, with the sn-2 position mainly esterified with arachidonic acid (34.8%) and the sn-1,3 positions mainly esterified with capric and lauric acids (35.1%). This work focuses on a simple process for the enzymatic production of structured TAG without prior purification of the sn-2 MAG.