Study on relative contents of principal components of different tea by infrared absorption spectroscopy

Fourier transform infrared absorption (FTIR) spectroscopy has been used to study the relative contents of principal components of different tea. Middle infrared (MIR) spectra in the range of 400~4000 cm^-1 has been obtained, which included six kinds of brand tea, corresponding remains and four kinds of component molecular. Contents of components in different kind of tea have been obtained by a new method that made spectral reconstruction based on five principal component model, particularly the remains of tea considered as primary components, as well as anthocyanic, theanine, epi-gallocatechin-3-gallaet and caffeine. All the correlation coefficient between original spectra of tea and reconstructive spectra are beyond 99% in the range of 800-2000 cm^-1. Meanwhile, the fitting results clearly showed that the relative contents and regularity of theanine, epigallocatechin-3-gallae and caffeine were consistent with the reported results in different kind of tea. Therefore, it was confirmed that this new method can be used to identify tea samples effectively.