Study on synthesis parameters of lipase-catalyzed hexyl acetate in supercritical CO2 by response surface methodology

Abstract: Hexyl acetate, a short-chain ester with fruity odor, is a significant green note flavor compound that is widely used in the food industry. The ability of immobilized lipase from Rhizomucor miehei (Lipozyme IM-77) to catalyze the transesterification of hexanol with triacetin in supercritical carbon dioxide was investigated in this study. Response surface methodology and a 3-level-3-factor fractional factorial design were adopted to evaluate the effects of synthesis variables, such as reaction time (30 to 90 min), temperature (35 to 55C), and pressure (1500 to 3500 psi), on percent molar conversion of hexyl acetate. The results showed that reaction time and pressure were the most important parameters and temperature had less effect on percent molar conversion. Based on canonical analysis, optimal synthesis conditions were as follows: reaction time 69.0 min, synthesis temperature 46.7C, pressure 2640 psi. The predicted value was 75.6% and the actual value was 77.3% molar conversion.