Effect of Reaction Medium Mixture on the Lipase Catalyzed Synthesis of Diacylglycerol

In this study, the implication of employing blended solvents during the synthesis of glycerol dioleates (GDO) using Candida antartica lipase was investigated. GDO is an example of diacylglycerol (DAG) that comprises two oleic acid chains esterified to one glycerol backbone. A model system consisting of glycerol and oleic acid was used to determine the effects of different solvent systems exhibiting various viscosities and polarities on conversion, yield, and selectivity of glycerol oleates. The study was carried out at different temperatures. The rheological properties of solventless, acetone, tert-butanol, and blended solvents systems exhibited Newtonian flow behavior, and their viscosities decreased at elevated temperatures. As compared to GMO and GTO, GDO synthesis showed the highest yield (70%) and selectivity (54%) at 40 °C within 2 h in the reaction medium containing blended solvents of tert-butanol/acetone. The rate of reaction and productivity of GDO in tert-butanol/acetone were achieved at 0.27 M h-1 and 0.48 M h-1, respectively. The tested systems were found to be endothermic and in a disordered manner at all investigated ranges of temperatures studied. The esterification reaction was found to be spontaneous, and the Gibbs energy decreased with increasing temperature.