奶茶中茶多酚含量测定方法的改进

Improvements on analysis of the content of tea polyphenols in milk tea

茶多酚含量的高低是评价茶饮料质量好坏的一个主要指标,GB/T21733-2008中采用酒石酸铁比色法测定茶饮料中茶多酚的含量,实际操作时,我们发现其中对奶茶类饮料的样品预处理存在一定缺陷,影响了测定结果的准确度。本文通过改进样品预处理方法,即采用酸性丙酮破乳和沉淀蛋白质,提高了奶茶饮料中茶多酚含量测定的精密度和准确度。方法的平均回收率为99.6%～102.2%,相对标准偏差RSD为0.21%～0.26%(n=6),可广泛应用于奶茶类饮料中茶多酚含量的测定。

The content of tea polyphenols was a major quality index of milk tea, and GB/T 21733-2008 based on iron tartrate colorimetry was usually applied to measure the content of tea polyphenols in milk tea.However, it was found that there were some defects in the process of sample pretreatment, which affected the accuracy of the testing result.In this study, acid acetone was used to destroy the emulsifying system and precipitate protein, a clarified and transparent solution was obtained ,which significantly increased the detection accuracy.The result showed that the recovery ratio reached 99.6%-102.2% and RSD kept as low as 0.21%-0.26% （ n = 6）, indicating its perspective application in measurement of tea polyphenols in milk tea.