用近红外光谱法检测绿茶中品质成分的研究

Determination of Quality Components in Green Tea by Near-infrared Reflectance Spectroscopy

通过对40个绿茶试样进行近红外光扫描和多元回归分析处理,求得绿茶的总氮量、游离氨基酸、咖啡碱、茶多酚等四种品质成分的近红外特征吸收波长,并建立计算多元回归方程式。选用31个未知茶样,用标准化学法来验证近红外法,其相关系数(r)和标准偏差(s),总氮量(r=0.993,s=0.0808),游离氨基酸(r=0.888,s=0.228)、咖啡碱(r=0.917,s=1.29),茶多酚(r=0.998,s=0.146)。并经t检验,近红外法和化学法测定结果差异不显著。因此,确认近红外光谱法可用于绿茶的品质检验。

The near-infrared reflectance(NIR) spectra of forty green tea samples were determined. The characteristic bands associated with the four quality contents, total nitrogen, free amino acids, coffeine, and tea polyphenols of green tea, were found, multiple linear regression analysis was done, and corresponding regression equation was established. The equations were verified with 31 green tea samples. The correlation coefficient(r) and the standard deviation of difference(s) are r=0. 993, s=0. 0808 for total nitrogen, r=0. 888, s=0. 228 for free amino acids, r=0. 917, s=1. 29 for coffeine, r=0. 998 s=0. 146 for tea polyphenols. T test showed that the results both chemical analysis and NIR analysis are in good agreement. It is concluded that NIR method can be used to determine the total nitrogen, free amino acids, coffeine and tea polyphenols in green tea.