Synthesis of medium and long-chain triacylglycerols by enzymatic acidolysis of algal oil and lauric acid

Abstract

To obtain medium and long-chain triacylglycerols (MLCTs) with high levels of lauric acid (LA) and docosahexaenoic acid (DHA), an acidolysis reaction was catalyzed by lipase in a solvent-free system to incorporate LA into algal oil (rich in DHA). Three regiospecific immobilized lipases were compared for their efficiency in the synthesis of MLCTs-riched structured lipids (SLs). The results showed that Lipozyme AOAB8 (from Aspergillus oryzae) displayed the top performance for LA incorporation of MLCTs-riched SLs. The optimum conditions of acidolysis reaction were: reaction temperature 65 °C, substrate mole ratio 1:8 (algal oil to LA), enzyme load 12 g/100 g total substrates, and reaction time of 2.5 h. Under these conditions, LA and DHA of the MLCTs-riched SLs production were 30.91% and 44.68%, respectively, and Lipozyme AOAB8 was reusable for at least 9 times. Melting and crystallization profiles revealed that the MLCTs-riched SLs production possessed preferable physical properties over the original algal oil. The MLCTs-riched SLs can be applied in human milk fat substitutes and dietary supplements as functional lipids.