Abstract
The synthesis of pineapple flavour (butyl butyrate) catalysed by lipase from Rhizomucor miehei has been optimized using central composite design and response surface methodology. Initially, the best butyric acid concentration in the mixture was defined and found that 1? m butyric acid presented the highest initial reaction rate. The reaction parameters substrate molar ratio, enzyme content, and initial added water were evaluated in the central composite design with the reaction conversion yield as the dependent variable. The optimal conditions for butyl butyrate synthesis were found to be substrate molar ratio of 3.6:1 butanol:butyric acid; enzyme content of 6.5% of substrate mass fraction; added water 0.0% of substrate mass fraction. Under these conditions, over 90% of conversion was obtained in 16?h of reaction. Enzyme reuse was tested performing a treatment before each batch by washing the enzyme system with n-hexane, or simply reusing the biocatalyst in a new fresh reaction. Direct enzyme reuse caused a rapid decrease on the enzyme activity, while washings with n-hexane allowed the enzyme to be reused for six cycles keeping around 75% of its original activity. Copyright (c) 2012 John Wiley & Sons, Ltd.