Combination of biocatalysis and sonochemistry in the ethyl oleate production

Fatty acid alkyl esters (FAAEs) are a family of natural neutral lipids and can be produced cleanly and sustainably by esterification of free fatty acids (FFAs) with short chain alcohols using enzymatic catalysts. In this study, it was evaluated the use of lipases in enzymatic esterification of oleic acid with ethanol using the combination of biocatalysis and sonochemistry (ultrasound) in the absence of co-solvents. Reaction parameters, such as type of lipase, amount of enzyme, reaction time, alcohol hydration level and enzyme turnover were evaluated for the enzymatic synthesis of ethyl oleate. C. antarctica lipase provided yields above 95% in less than 10 h with 10% (w/w) of lipase. The use of hydrous ethanol (5% of water) showed a slight drop in yield but remained above 90% of ethyl oleate production. C. antarctica lipase showed no loss of efficiency even after 10 reaction cycles. The combination of biocatalysis and ultrasound radiation provided a high yield, showing that the combination of these tools may be a good choice for the enzymatic synthesis of ethyl oleate.