基于傅里叶变换红外光谱的不同茶山古树普洱茶鉴别研究

目的 基于混合物红外光谱原理及方法,对不同茶山普洱茶组成差异进行整体分析与评价,探讨普洱茶一山一味说法的科学性.方法 选取易武、景迈等云南12座茶山的古树晒青茶,采用透射法傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FT-IR)采集其超微茶粉、水提取物及茶渣的...

Discrimination study of Pu-erh tea made from ancient trees from different tea mountains based on Fourier transform infrared spectroscopy

Objective To analyze and evaluate the overall composition differences of tea samples from different ancient tea mountains based on the principle and method of mixture infrared spectroscopy, and explore the scientific nature of the statement one mountain, one flavor of Pu-erh tea. Methods The infrared spectra of the ultra-fine tea powders, water extracts and extraction residues from the sun-dried raw tea of ancient trees from 12 tea mountains in Yunnan province, such as Yiwu and Jingmai were collected, and the infrared spectra were processed into standardized infrared spectra and second derivative infrared spectroscopy (SD-IR), furthermore, the similarity evaluation, spectral difference analysis and characteristic peak intensity analysis based on those spectra were carried out for the discrimination and evaluation of the substance composition differences among different tea samples. Results All spectral correlation coefficients (R) were over 0.98 and all 12 kinds of tea samples had common FT-IR peaks at 3354, 2925, 1649, 1517, 1451, 1239, 1147, 1039, 764, 611 cm?1 and so on, even so, SD-IR peaks including 1649, 1577, 1568, 1540, 1532, 1147 and 486 cm?1 had different absorption intensities or peak shapes. Tea samples from Jinggu, Yiwu and Hekai had relative low peak intensities at 486 cm?1, that from Jinggu was the lowest, which was only about 75% to the tea from Youle. The overall chemical compositions of the 12 kinds of tea samples were very similar, the caffeine content in Jinggu, Yiwu and Hekai tea samples was relative lower than that of others, but the spectral differences with other tea samples were only less than 2%, but the relative content of caffeine in different tea samples could be conveniently compared based on the SD-IR peak intensity at 486 cm?1, Tea samples from different tea mountains could be thoroughly discriminated according to SD-IR spectral differences. Conclusion More or less compositional differences among tea samples from different tea mountain can be appeared in their FT-IR spectra, FT-IR analytical method is suitable for the overall identification and evaluation of the composition differences of Pu-erh tea samples, to some extent, the statement of one mountain, one flavor about Pu-erh tea has a certain scientific nature.