Parameters study of lipase-transesterification reaction of ethyl caffeate and glycerol in deep eutectic solvent (DES)

Abstract

The toxicity of organic solvent to human and environment has triggered researchers to find an alternative green solvent for the past 20 years. Deep eutectic solvent (DES) is the newly emerging green solvent that is being utilized in biocatalysis. The boiling point of DES is higher than conventional organic solvent thus enables for lipase to perform at its optimum temperature. However, the transesterification reaction in DES is limited due to its high viscosity. Therefore, water was added to DES media to reduce its viscosity. This study reported on the use of choline-based DES for lipase-catalyzed transesterification of ethyl caffeate and glycerol. The transesterification reactions in DES comprised of choline chloride and urea at molar ratio 1:2 resulted in high conversion of ethyl caffeate (over 90%) under the following parameters : enzyme loading (1250 Unit Activity); amount of water (20 vol%) and agitation speed (200 rpm). This work could provide an insight to the potential of DES as a promising alternative solvent for the production of glyceryl caffeate esters due to high conversion, faster reaction time and reduction of dangerous organic solvent consumption.