茶渣对酯型儿茶素的选择性吸附性能研究
Effects of tea residue on selective adsorption properties of ester-catechins

【目的】研究茶渣对酯型儿茶素的选择性吸附性能，为获得脱咖啡碱的高纯度儿茶素类产品及茶渣的再利用提供参考。【方法】以一次浸提、二次浸提、乙醇处理和酸碱处理共4种方式处理茶渣，比较咖啡碱及酯型儿茶素（表没食子儿茶素没食子酸酯（Epigallocatechin gallate，EGCG）、没食子儿茶素酸酯（Gallocatechin gallate，GCG）、表儿茶素没食子酸酯（Epicatechin gallate，ECG）、儿茶素酸酯（Catechin gallate，CG））吸附量的大小，选择茶渣最佳处理方式；测定乙醇处理后茶渣对茶汤中相关成分的动态吸附过程；分析比较茶汤质量浓度分别为2，5，10，15，20 mg/mL 以及液固比（茶汤体积（mL）与茶渣质量（g）的比值）分别为20∶1，40∶1，80∶1，100∶1，180∶1时，茶渣对咖啡碱及酯型儿茶素吸附量的影响。【结果】乙醇处理茶渣吸附性能最好，其对酯型儿茶素EGCG、GCG、ECG、CG的吸附量分别为25.67，8.44，7.60和2.44 mg/g，咖啡碱与酯型儿茶素的吸附量比值为0.098。吸附时间为70 min时，酯型儿茶素的吸附量已达最大值，但咖啡碱尚未达到饱和。茶渣对酯型儿茶素的吸附量与茶汤质量浓度呈线性正相关；酯型儿茶素和咖啡碱的吸附量随茶汤体积与茶渣质量间的液固比的增大而增加，但综合考虑吸附量、咖啡碱脱除效果与茶汤利用率，液固比以40∶1为宜。【结论】茶渣对酯型儿茶素具有选择性吸附效果，在不同吸附时间以及不同茶汤质量浓度与液固比下，酯型儿茶素与咖啡碱的吸附量呈现不同的变化特征，据此设计工艺方案有助于提高茶渣的选择性吸附效率。
【Objective】The effects of tea residue on selective adsorption properties of ester-catechins were researched in this paper to provide reference on obtaining high purity catechins products with low caffeine and reusing tea residue.【Method】Tea residue was treated by 4 methods,one time water extraction,two times water-extraction,ethanol treatment,and acid and alkali treatment.The adsorption amounts of caffeine and catechins (Epigallocatechin gallate (EGCG),Gallocatechin gallate (GCG),Epicatechin gallate (ECG),and Catechin gallate (CG)) were compared to obtain the best treatment method.The dynamic adsorption process of the ethanol treated tea residue was determined to compare the effects of tea residue on adsorption of ester-catechins when tea concentrations were 2,5,10,15 and 20 mg/mL and liquid-solid ratios were 20∶1,40∶1,80∶1,100∶1 and 180∶1.【Result】The ethanol treated tea residue was the best with adsorption capacities on EGCG,GCG,ECG,and CG of 25.67,8.44,7.60,and 2.44 mg/g,respectively,and the ratio of caffeine to ester catechins was 0.098.After 70 min,the adsorption of ester-catechins had reached its maximum while the adsorption of caffeine had not.The adsorption of ester-catechins had a linear correlation with tea concentration.The adsorption capacities of ester-catechins and caffeine increased with the increase of volume of tea and liquid solid ratio.But considering the adsorption capacity,caffeine removal effect and utilization rate of tea,40∶1 was suggested for liquid-solid ratio.【Conclusion】Tea residue could absorb ester-catechins selectively.Besides,ester-catechins and caffeine showed different characteristics in dynamic process and different relationships between adsorption capacities and tea concentration and liquid-solid ratio.This study was beneficial to improve the selective adsorption efficiency of tea residue