Enzymatic sythesis of Isoamyl butyrate under microwave irradiation

The enzymatic synthesis of isoamyl butyrate possessing fruity banana flavour and under high demand in commercial market, is carried out under microwave irradiation. The influence of various reaction parameters was studied and optimised that drive the reaction under solvent free condition to achieve maximum yield. At temperature 60 °C, 1:2 mole ratio of butyric acid: isoamyl alcohol, 2 % (w/v) of lipase loading with 700 W microwave power, 95% conversion was obtained in 120 min. The thermodynamic parameters were also determined and compared with the synthesis performed in conventional mechanical stirring and ultrasonic systems. The activation energy was found to be the lowest in presence of microwave energy than in other treatments thus enhancing the rate of reaction. The reusability studies showed that immobilised lipase was reusable for 7 successive cycles with 37 % loss from its initial activity. Thus, microwave energy as a greener and clean technique for synthesis was successfully intensified the esterification reaction as compared to conventional mechanical stirring by 5-folds and 1.5 fold than ultrasound system.