[Identification of Pu' er tea by Fourier transform infrared spectroscopy].

In the present paper, Fourier transform infrared spectroscopy (FTIR) was used to determine unzymic and zymic Pu'er tea of different grade produced in Simao, Yunan Province. Because of the different processing technology, different proportion of chemical constituents exists in the unzymic and zymic Pu'er tea. And although there is a great mass of similarity in infrared spectrum, the results still show differences in the characteristic peaks of infrared spectrum between unzymic and zymic Pu'er tea. And there is also obvious difference between unzymic Pu'er tea of different grade or zymic Pu'er tea of different grade. According to the studies of the spectral peaks and absorbance ratios, unzymic and zymic Pu'er tea can easily be identified. And different grade of unzymic and zymic Pu'er tea may be classified by the differences in the absorbance ratios of several peaks. FTIR is proved to be a rapid, simple, reliable and non-destructive qualification method, it is suitable for grade identification of Pu'er tea.