Enzyme as biocatalyst for synthesis of octyl ethanoate using acoustic cavitation: Optimization and kinetic study

Octyl ethanoate, an aliphatic ester which is well-known for its use in different industries such as food, pharmaceutical, cosmetic etc. mainly as fixative, modifier and aromatic ester. This work focuses on the use of acoustic cavitation as ultrasound assisted lipase i.e. Novozym 435 catalyzed synthesis of Octyl ethanoate via transesterification of octanol and vinyl acetate in non-aqueous, solvent free reaction. Optimization of various parameters showed that a higher yield of 97.31% can be obtained at octanol to vinyl acetate ratio of 1:2 with 0.03% catalyst, temperature 40 °C and 300 rpm, with lower ultrasound power input of 50 W, at 25 kHz frequency and 50% duty cycle. Further, the time required for the maximum conversion is reduced to 20 min as compared to 90 min of conventional process. Likewise, the enzyme can be successfully reused seven times without loss of enzyme activity. Thus, ultrasound helps to enhance the enzyme catalyzed synthesis of flavors. Analysis of the initial rate and progress curve showed that reaction obeys ternary complex bi bi mechanism with inhibition by octanol.