Meng, G; Liu, Y; Lei, S; Liu, G; Wang, C; Wen, Y
The influence factors of ester aromas with lipase catalysis of fusel oil in non-aqueous media system were studied via screening suitable lipase, optimizing the conditions of enzymatic conversion, and the effect of ultrasonic processing on enzymatic conversion was also studied. The results showed that the esterification activity of immobilized lipase Novozym 435FG was high and easy to recycle, and the yield of isoamyl acetate was 92.62%. The addition of dehydrating agent molecular sieve promoted the esterification reaction. The yield of ester aromas was affected by addition times and time interval of acetic acid, reaction temperature, reaction time, shaking speed, and ultrasonic field intensity. The optimized conditions by orthogonal test design were as follows: 1.5 mL acetic acid added in six times, the interval time of 3 h, the reaction time of 36 h, the molecular sieve of 2 g, the fusel oil of 3 mL, the lipase of 70 mg, the reaction temperature of 45â, the shaking speed of 140 r/min, and the yield of isoamyl acetate, isobutyl acetate and propyl acetate reached (89.2±0.7)%, (89.3±0.6)% and (76.8±0.9)%, respectively, which closed to ester yield in hexane reaction system. At the ultrasonic frequency of 50 Hz and ultrasonic power of 0.5 W/cm2 for 6 h, the yield of ester aromas reached 85%. It indicated that proper ultrasonic treatment could greatly accelerate the reaction process and shorten the reaction time. However, the ultimate production and yield after ultrasonic treatment did not increase, and long-time ultrasonic cavitation led to changing the microenvironment of the system and reducing the stability and use frequency of immobilized enzyme. © 2021, Editorial Department of Journal of Food Science and Technology. All right reserved.