Biocatalyzed acidolysis of soybean oil triacylglycerols to increase oleic acid content

Lipase catalyzed acidolysis of triacylglycerols (TAG) of soybean oil with oleic acid in organic solvent was studied; immobilized lipase from Rhizomucor miehei was used and the effects of reaction time, incubation temperature and enzyme load on TAG total and positional fatty acid (FA) percentage compositions were investigated. The results show that oleic acid incorporation was high after 24 and 48 h, while after 72 h a lower level of oleic acid in TAG was observed. Moreover, for the reactions carried out at 30 and 40 °C, it was observed that the oleic acid level was about 46.5% while ligtly higher values (about 49%) were observed at 50 °C; however, under this last condition, the modification of sn-2 position FA composition was higher. Finally, the variable enzyme load resulted also important on the incorporation of oleic acid; in particular, even if the value of 10% (w/w) of enzyme load resulted in a lightly lower incorporation of oleic acid in soybean oil TAG (about 45%), in this situation a minimal modification of sn-2 position FA composition was obtained.