Optimized synthesis of lipase-catalyzed hexyl acetate in n-hexane by response surface methodology

Hexyl acetate, a short-chain ester with fruity odor, is a significant green note flavor compound and widely used in the food industry. The ability for immobilized lipase from Mucor miehei (Lipozyme IM-77) to catalyze the tran sesterification of hexanol with triacetin was investigated in this study. R esponse surface methodology and five-level-five-factor central composite ro tatable design were adopted to evaluate the effects of synthesis variables, such as reaction time (2-10 h), temperature (25-65 degreesC), enzyme amoun t (10-50%; 0.024-0.118 BAUN), substrate molar ratio of triacetin to hexanol (1:1 to 3:1), and added water content (0-20%) on percentage molar conversi on of hexyl acetate. The results showed that reaction temperature and subst rate molar ratio were the most important parameters and that added water co ntent had less of an effect on percent molar conversion. On the basis of ca nonical analysis, optimum synthesis conditions were as follows: reaction ti me, 7.7 h; temperature, 52.6 degreesC; enzyme amount, 37.1% (0.089 BAUN); s ubstrate molar ratio, 2.7:1; and added water, 12.5%. The predicted value wa s 88.9% molar conversion, and the actual experimental value was 86.6% molar conversion.