Abstract: The discrimination of tea category based on FTIR and stepwise discriminant analysis was studied, using the synchronous modeling and specific tea modeling with Oolong tea, green tea, black tea and white tea as the samples. The results showed that the recognition accuracy of the resubstitution and external validation of tea category using synchronous modeling based on absorption values at 1 000~1 800 cm^-1 band, the absorption ratio in the main peak, the extracted modeling factors of the former two were 84.8% and 85.0%, 81.9% and 80.0%, 89.0% and 88.5% respectively. The recognition accuracy of the resubstitution and external validation of tea category using specific tea modeling based on the three methods were 94.2% and 95.0%, 89.2% and 90.0%, 93.0% and 95.0% respectively, and 4 discriminant functions of synchronous analysis and specific tea analysis which can discriminate these four kinds of tea effectively were established respectively. The results also indicated that the effect of tea-specific modeling was better than synchronous modeling.

Key words: tea category, fourier infrared spectra, stepwise discriminant analysis