Synthesis of symmetrical medium- and long-chain triacylglycerols rich in arachidonic acid at sn-2 position for infant formula

Medium-and long-chain triacylglycerols (MLCT) rich in arachidonic acid (ARA) at sn-2 position were synthesized by a two-step enzymatic method. Firstly, sn-2 monoacylglycerols (MAG) were synthesized at a temperature of 25 degrees C by enzymatic alcoholysis. The MAG with 69.42% ARA at sn-2 position were obtained by solvent extraction and low temperature solvent crystallization. Secondly, the MLCT rich in ARA at sn-2 position and capric acid (CA) at sn-1,3 positions were produced by enzymatic esterification. Under the optimal conditions (MAG:CA = 1:3 (mol/mol), 0.05 MPa vacuum, 8% Lipozyme RM IM, 5 h, 25 degrees C), the content of triacylglycerol was up to 93.60%. The triacylglycerol in the form of C10:0-C20:4-C10:0 (including isomers) was about 40.43%. The ARA contents in the total and sn-2 fatty acid composition of the final product were 32.35% and 51.12%, respectively. MLCT rich in ARA at sn-2 position were successfully produced and the product has the potential application for functional food and infant formula.