摘要
基于高剪切分散乳化(High shear dispersing emulsification,HSDE)技术,以20%乙醇水溶液作为提取溶剂,研究了茶叶中4种多酚类化合物(表没食子儿茶素、表没食子儿茶素没食子酸酯、没食子儿茶素没食子酸酯、表儿茶素没食子酸酯)、没食子酸和咖啡因的提取动力学和热力学。以动力学理论为基础,建立了4种茶多酚类化合物、没食子酸和咖啡因的提取动力学方程,并计算得到速率常数k;以热力学理论为基础,计算得到焓变、熵变、自由能变等热力学参数。进一步探讨了该方法的提取机理。HSDE提取法的最佳条件为:提取溶剂为20%乙醇水溶液,料液比为1∶50,转速为10 000 r/min,剪切时间为180 s,体系温度为313.15 K。在此条件下,茶叶中有效成分的提取率高达95%。与其他茶叶提取方法相比,HSDE提取法具有提取速度快、溶剂耗量少、提取率高等优点,具有较好的应用前景。
By virtue of high shear dispersing emulsification （HSDE） technology, the extraction of four kinds of polyphenols （ e. g. （ - ）-epigallocatechin gallate , （-）-epigallocatechin, （-）-epicate- chin gallate, and （ - ）-gallocatechin gallate）, gallic acid and caffeine in the tea leaves was studied by using 20% ethanol aqueous solution as extraction solvent. The kinetics and thermodynamics of the extraction process were investigated. The kinetic equations in extraction process of the four kinds of polyphenols, gallic acid and caffeine were obtained according to kinetic theory, and the rate constant k was also calculated. The values of thermodynamic parameters such as enthalpy, entropy and free energy were computed based on thermodynamic theory. Furthermore, the extraction mechanism was explored on the basis of kinetic and thermodynamic analyses. The optimal conditions of the extraction method through HSDE technology were as follows： extraction solution： 20% alcohol aqueous solu- tion, solid-liquid ratio： 1 ： 50, rotation speed： 10 000 r/min, extraction time： 180 s, extrac- tion temperature： 313.15 K. Under the optimum conditions, the extraction efficiencies of active in- gredients in tea leaves could leaves, the proposed method reach up to 95%. Compared with possesses many advantages such as other pretreatment methods for tea higher extraction speed, less con- sumption of extraction solution and higher extraction efficiency. The method would have a good pros-pect in application of the extraction of natural product.
出处
《分析测试学报》
CAS
CSCD
北大核心
2013年第4期401-407,共7页
Journal of Instrumental Analysis
基金
国家自然科学基金资助项目(20974116)
关键词
高剪切分散乳化技术
动力学
热力学
茶叶
茶多酚
high shear dispersing emulsification
kinetics
thermodynamics
tea leaves
polyphe-nols
