微波辅助萃取蓝莓花色苷工艺优化及热动力学分析

Optimization of microwave assisted extraction of anthocyanins from blueberry and its thermokinetic analysis

目的:提高蓝莓花色苷萃取率,克服传统萃取缺点。方法:利用单因素试验探究4个试验因素对花色苷得率的影响;在此基础上,利用响应面设计组合试验,并通过遗传算法优化其提取工艺。依据Fick第一定律建立MAE过程中的动力学模型;依据Arrhenius方程和相变平衡原理,获得MAE过程中的活化能(E_(a))、熵变(ΔS)、焓变(ΔH)和吉布斯自由能变(ΔG),分析MAE过程的热力学。结果:MAE蓝莓花色苷最佳工艺条件为萃取温度60℃、萃取时间8 min、乙醇体积分数57%和料液比1∶32(g/mL),花色苷萃取率为(83.15±2.03)%。建立的动力学模型能较好地预测不同萃取温度下,花色苷萃取效果。在MAE过程中,E_(a)、ΔS和ΔH分别为40510.00,42.07,190.64 J/mol,ΔG小于零。结论:MAE过程属于吸热、熵增加、自发的过程。

Objective:To improve the extraction rate of blueberry anthocyanins and overcome the shortcomings of traditional extraction.Methods:Firstly,single factor experiment was used to explore the effects of four experimental factors on the yield of anthocyanins.Response surface methodology was used to design the combination experiment,and genetic algorithm was employed to optimize the extraction process.The dynamic model of MAE process was established based on Fick’s first law.According to Arrhenius equation and phase transition equilibrium principle,E_(a),ΔS,ΔH,andΔG in the extraction process were obtained to analyze the thermodynamics of microwave extraction process.Results:The optimum extraction parameters to achieve the highest yield of anthocyanins(83.15±2.03)%from blueberry via MAE were obtained at extraction temperature of 60℃,extraction time of 8 s,ethanol concentration of 57%,and solid-to-liquid ratio of 1∶32(g/mL).The established kinetic model could predict the extraction effect of anthocyanins at different extraction temperatures.In the process of microwave extraction,the E_(a),ΔS,andΔH were 40510 J/mol,42.07 J/mol,and 190.64 J/mol,respectively.ΔG was less than zero,indicating that the microwave extraction process belonged to endothermic,entropy increasing and spontaneous process.Conclusion:The results provide theoretical basis and reference for the efficient extraction and deep development of anthocyanins.