LP-8大孔树脂制备高含量酯型儿茶素茶多酚

Use of Macroporous Resin LP-8 for Preparing Tea Polyphenols Rich in Esteri?ed Catechins

结合当前茶学中酯型儿茶素研究热点和工业生产中差异化茶多酚产品需求,对LP-8大孔树脂分离制备高含量酯型儿茶素茶多酚开展研究。先经静态吸附和洗脱实验表明LP-8大孔树脂对茶多酚(含酯型儿茶素)和咖啡碱具有较大的吸附选择性差异,用体积分数70%乙醇溶液洗脱即可获较理想的茶多酚回收率,因此确定LP-8树脂具有分离制备高含量酯型儿茶素茶多酚的可行性。再经静态吸附动力学和等温吸附实验,结合Langmuir拟合方程推算,25℃下LP-8大孔树脂的饱和吸附量为70.9 mg/g。经动态吸附实验,确定了最佳吸附条件为上样流速1 BV/h、上样质量浓度30 mg/mL,利用不同体积分数的乙醇溶液对饱和吸附样进行梯度洗脱,40%～60%洗脱合并液中酯型儿茶素占茶多酚比例达78.0%(表没食子儿茶素没食子酸酯占茶多酚总量的61.0%),即利用LP-8大孔树脂获得了高含量酯型儿茶素茶多酚。

In the light of the current great interest in esterified catechins in tea science and the demand for diverse industrial products of tea polyphenols, macroporous resin LP-8 was chosen to separate tea polyphenols with high proportion of esterified catechins in this study. In static adsorption and desorption experiments, resin LP-8 was proven to have differential selectivity for tea polyphenols(containing esterified catechins) and caffeine. Ideal recovery of tea polyphenols could be subsequently obtained by elution with 70% ethanol. As a result, resin LP-8 is promising to prepare tea polyphenols with high proportion of esterified catechins. Furthermore, static adsorption kinetics and isothermal adsorption experiments were conducted, and the saturated adsorption capacity of resin LP-8 at 25 ℃ was calculated to be 70.9 mg/g by fitting the data obtained to the Langmuir equation. The optimal dynamic adsorption conditions were determined as 1 BV/h of loading flow rate and 30 mg/mL of sample concentration. Different concentrations of ethanol were used in gradient dynamic desorption, and the tea polyphenols in the pooled sample of 40%–60% ethanol eluates contained 78.0% esterified catechins(61.0% epigallocatechin gallate(EGCG)). In conclusion, tea polyphenols with high proportion of esterified catechins were successfully obtained by the application of macroporous resin LP-8.