超声波辅助离子液体提取石榴籽中原花青素的工艺及其动力学与热力学分析

摘要

探讨了超声波辅助离子液体提取石榴籽中原花青素的工艺条件,以原花青素得率为考察指标,提取时间、提取温度、超声功率和离子液体浓度为实验因子,在单因素实验基础上,通过Box-Behnken实验设计优化最佳提取工艺条件,并对提取过程的动力学和热力学性质进行了分析.结果显示:原花青素的最佳提取工艺条件为:提取时间32 min、提取温度52℃、超声功率300W、离子液体浓度1.15 mol/L,此条件下的原花青素得率达到1.718％;在该工艺参数下,提取速率常数k值为0.313 min-1,表面扩散系数Ds值为7.936×10-5 cm2/min,而相同提取条件下,无水乙醇空白对照组的k值仅为0.063 min-1,表面扩散系数Ds值为1.597×10-5 cm2/min,提取速率明显提高;提取过程的热力学参数,熵△H为248.51 kJ/mol,焓△S为813.69 J/(mol· K),数值均大于零,说明离子液体提取过程为吸热熵增加过程,自由能AG为-18.254 kJ/mol,小于零,为自发过程.离子液体提取的工艺参数及动力学与热力学分析,均可用于石榴籽中原花青素提取过程的工程放大和优化控制.%The ionic liquid based ultrasonic-assisted extraction conditions of proanthocyanidins fron pomegranate seeds were studied.Single factor test and Box-Behnken experimental design were used to optimize the extraction process employing proanthocyanidins yield as the response,and extraction time,extraction temperature,ultrasonic power and concentration of ionic liquid were used as independent variables.The kinetics and thermodynamics of extraction process was studied basing the optimized extraction conditions.Results showed that the optimal extraction conditions for proanthocyanidins were determined as follows:extraction time of 32 min,extraction temperature of 52 ℃,ultrasonic power of 300 W,and concentration of ionic liquid of 1.15 mol/L.Under these conditions,the yield of proanthocyanidins was 1.718％.Kinetic parameters showed that extraction rate constant k value was 0.313 min-1,surface diffusion coefficient Ds value was 7.936 × 10-5 cm2/min while those of ethanol control group were 0.063 min-1 and 1.597 × 10-5 cm2/min,respectively,and the extraction rate was significantly improved.Thermodynamics parameters showed that entropy ΔH was 248.51 kJ/mol,enthalpy ΔS was 813.69 J/ (mol· K),the values were all greater than zero,indicating that the ionic liquid extraction process was an endothermic process of increasing entropy,at the same time,the free energy ΔG was-18.254 kJ/mol,less than zero,indicating that the ionic liquid extraction process was a spontaneous process.Both the optimized ionic liquid extraction technique and dynamics/thermodynamics analysis can be used for industrial scale-up and optimal control of proanthocyanidins extraction from pomegranate seeds.