发芽蚕豆左旋多巴超声强化提取及其动力学过程

为了充分提取和利用高生物活性的天然左旋多巴(L-DOPA),研究了超声波强化提取发芽蚕豆L-DOPA的工艺条件,并初步探讨了超声浸提动力学过程。基于单因素试验,以超声功率、液固比、萃取时间为考察因素,采用Box-Behnken试验设计进行了工艺参数优化,结果表明,超声功率对发芽蚕豆L-DOPA得率的影响较大;原料用量2.0g,采用含30%乙醇的0.1mol/L醋酸溶液为提取溶剂,其较佳提取工艺条件为:超声功率257W、液固比31mL/g、萃取时间为37.4min。在此条件下,发芽蚕豆L-DOPA的平均得率为1.47%,较未发芽蚕豆增加0.58倍,略高于传统提取法,且超声强化提取显著缩短了浸提时间。对最优提取条件下L-DOPA得率随时间变化的动力学分别用Film模型、非稳态扩散理论和Ponomaryov经验方程进行拟合,其中Film理论模型的拟合度较好,其决定系数R2值最大,为0.9928。研究结果为天然L-DOPA制备提供了参考。

Optimization and kinetics for ultrasonic-assisted extraction of L-dopa from fava bean (Vicia faba L.) sprouts

In order to fully extract and utilize high bioactive natural L-DOPA (Levo-dihydroxy phenylalanine), the present study was undertaken to explore the potential applicability of ultrasonic waves to isolate L-DOPA from germinated sprouts, extraction kinetics were also preliminarily studied. Based on single factor experiments, a Box-Behnken design (BBD) was applied to optimize the processing conditions for the ultrasonic-assisted extraction (UAE) of L-DOPA in germinated fava bean sprouts and evaluate the effects of three independent variables (ultrasonic power, liquid-solid ratio and extraction time on the yield of L-DOPA. The results showed that ultrasonic power was the most important factor, the maximum yield of L-DOPA (1.47%) was found when 2.0 g germinated sprouts was extracted with 30% (by vol.) ethanol-0.1 M acetic acid solution at ultrasonic power 257 W, liquid-solid ratio 31 mL/g and extraction time 37.4 min. Under the optimum UAE conditions, L-DOPA recovery of the germinated sprouts was a little higher than that of conventional solvent extraction (CSE) and represented almost 0.58-fold increase when compared with ungerminated sprouts, UAE significantly shortened the time required for the extraction process. The yields of L-DOPA at different extraction time were simulated by three kinetic models, .i e. the film theory, the unsteady diffusion through plant and the empirical equation of Ponomaryov. The film model gave good simulation to the experimental data with the highest R2 at 0.9928. The results can provide a reference for natural L-DOPA preparation.