杂醇油酶法制备天然等同酯香料的研究

Preparation of Natural Equivalent Ester Aromas with Lipase Catalysis of Fusel Oil

研究了无溶剂体系中杂醇油酶法转化制备天然等同酯香料的影响因素,筛选适宜脂肪酶,优化工艺条件,研究超声处理对酶法制备酯香料的作用。结果表明:在无溶剂体系中固定化脂肪酶Novozym 435FG的酯化活力高且易回收,乙酸异戊酯产率达到92.62%;除水剂分子筛的加入促进了酯化反应,乙酸加入次数和间隔时间、反应温度和反应时间、摇床转速及超声处理对酯香料的产率均有影响。酶法制备酯香料的较优条件为1.5 mL乙酸分6次加入、间隔时间3 h、反应时间36 h、分子筛添加量2 g、杂醇油3 mL、脂肪酶加入量70 mg、温度45℃、转速140 r/min,其乙酸异戊酯、乙酸异丁酯、乙酸正丙酯的产率分别达到(89.2±0.7)%、(89.3±0.6)%、(76.8±0.9)%,与正己烷反应体系的酯产率接近。在超声频率50 Hz、单位面积超声功率0.5 W/cm2处理6 h时酯香料产率达85%,说明适当超声处理可加速反应进程,显著缩短反应时间,但超声处理的酯香料最终产量和产率未见增加,且长时间超声空化作用造成体系微环境改变,降低了固定化酶稳定性和使用次数。

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 45℃,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.