反式儿茶素类与表儿茶素类浸提规律的比较研究

Comparative Research on the Extraction Regularity of Trans-Catechins and Epicatechins

利用HPLC分析技术,测定茶叶儿茶素中8种单体在沸水浸提过程中的浓度-时间变化,结合浸提动力学基本模型,对表儿茶素类与反式儿茶素类单体的沸水浸提动态进行系统研究,分析EGCG/总儿茶素、GCG/总儿茶素的动态变化。结果表明,表儿茶素类的浸提速率显著快于反式儿茶素类,浸提率于5 min时达到最大值,之后随着时间延长而下降;反式儿茶素类的浸提率则一直处于明显增长状态,浸提结束时达到最高值。根据浸提速率常数Kobs,8种单体的浸出快慢顺序为:EC>EGC>EGCG>ECG>GC>C>GCG>CG。

Using the HPLC technique,changes of concentration of eight catechin monomers versus time in boiling infusion were measured.Extraction kinetics of epicatechins and trans-catechins were systematically studied by applying a two-phase model in determining the kinetic and equilibrium data.Dynamic changes of ratios of EGCG and GCG to total catechin were studied,too.The results showed that epicatechins infused faster than trans-catechins dramaticlly,the former reached its maximum at 5 min,then the value declined with time.While trans-catechins extraction rate increased steadily with time,reaching the peak value at the end of infusing.According to the rate constant Kobs,the order of extraction velocity of eight catechin monomers was as follows： ECEGCEGCGECGGCCGCGCG.