普洱生茶和熟茶中咖啡因含量测试

Studies on Caffeine Content in Pu-Er Crude Tea and Pu-Er Ripe Tea

用热水浸提法分别提取15个普洱生茶样品和15个普洱熟茶样品中的咖啡因,采用紫外分光光度法,以咖啡因为标准品,蒸馏水为空白对照,于274 nm波长处分别测定对照品和供试品溶液的吸光度,按标准曲线计算咖啡因含量。回归方程为y=47.945x+0.0015,R2=0.9999。15个普洱生茶样品中的咖啡因平均含量4.29%,15个普洱熟茶样品中咖啡因平均含量为3.31%。

Caffein was respectively extracted from 15 kinds of Pu-Er crude tea and 15 kinds of ripe tea by the boiling-water method.The caffein content was respectively determined by the ultraviolet spectrophotometric method,taken caffein as reference standard and the distilled water as the blank control,the absorbance of the reference and test solution was determined at 274 nm and the content of caffein was calculated by using the standard curve.The regression equation was y=47.945x＋0.0015,R2=0.9999（Y and X stand for absorbance and concentration of caffein respectively）,the average percentage composition of caffeine in Pu-Er crude tea was 4.29%,3.31% in Pu-Er ripe tea.The caffeine content of Pu-Er ripe tea is reduced during manufacturing process.