Enzymatic-catalyzed esterification of free fatty acids to methyl esters

Enzymatic transesterification of fatty acid oils to fatty acid methyl esters (FAME) is a wellestablished process involving an enzymatically catalyzed transesterification reaction step with yields greater than 97%. The unreacted residual consists primarily of free fatty acids (FFA), which contribute to the acid value (mg KOH/g biodiesel) and are typically 2–3 wt%. Water is critical to the stability and activity of the enzyme employed in the transesterification reaction. Consequently, reducing the residual FFA further is not possible with the existing process.