Studies on the optimized lipase-catalyzed biosynthesis of cis-3-hexen-l-yl acetate in n-hexane

Cis-3-hexen-1-yl acetate, wildly used in the food industry, is a short-chain ester with fruity odour that is a significant model of a flavour compound with natural green notes. The aim of this work was to evaluate the ability of immobilized lipase from Rhizomucor miehei (Lipozyme IM-77) to catalyze the transesterification of cis-3-hexen-1-ol with triacetin in n-hexane. Response surface methodology and a 5-level-5-factor central composite rotatable design were adopted to evaluate the effects of synthesis parameters, such as reaction time (8-24 h), temperature (25-65 degreesC), enzyme amount (0.02-0.1 BAUN), substrate molar ratio of triacetin to cis-3-hexen-1-ol (1:1 to 3:1), and added water content (0-20%) on the percentage molar conversion of cis-3-hexen-1-yl acetate. Reaction temperature and substrate molar ratio was the most important parameters and added water content had less effect on percent molar conversion. Based on ridge max, maximum transesterification conditions were: reaction time 19.2 h, temperature 48.5 degreesC, enzyme amount 0.09 BAUN, substrate molar ratio 2.5: 1, and added water 7.85%. The maximum predicted value of molar conversion was 82.1% and the actual experimental value 80.9% molar conversion. (C) 2002 Elsevier Science B.V. All rights reserved.