Synthesis of isoamyl acetate by ultrasonic system using Candida antarctica lipase B immobilized in polyurethane

Abstract Synthesis of isoamyl acetate by mechanical and ultrasonic solvent‐free agitations using Candida antarctica lipase B (CALB) as biocatalyst immobilized in polyurethane was studied. Temperature (24.8–75.2 °C), ultrasonic power (35–123 W; only in ultrasonic system) and molar ratio of substrates (1:3.64–1:10.36) were the parameters evaluated. The responses taken into account were the acetic acid conversion in the esterification reaction (21–95%) and the residual conversion of substrates after successive reuse cycles of CALB. Ultrasonic system was advantageous because the substrate conversions into isoamyl acetate were reached six times earlier than in mechanical system. An increase in the temperature and ultrasonic power and a reduction in acetic acid : isoamyl alcohol ratio favored an increase in conversion yields. CALB used in ultrasonic reactions maintained more than 60% of its residual activity after 27 reuse cycles, which was more than thrice (eight reuse cycles) when using CALB in mechanical reactions. Practical applications The practical uses of isoamyl acetate are mainly as a food additive and as a solvent in the aircraft industry. In food‐related areas, this ester is used to confer characteristics such as banana (or pear) smell and flavor in foods and beverages. It has a pleasant odor and low toxicity, which encourages its widespread use in different receipts, including in the formulation of beers.