| Instant tea and tea polyphenol product are two common kinds of tea products. Instant tea is a kind of solid beverage produced by tea, tea by-product or fresh tea leaves through a series of processing technology, it is soluble in water. Tea polyphenol product is extracted from tea. This paper mainly discussed measurement methods of moisture and total polyphenols’content in tea polyphenol products, component analysis of tea products, NIR rapid determination method and fingerprint study on tea products.It was investigated that the moisture and total polyphenols’ content measurement method of tea polyphenol products firstly, the results showed that the prior moisture content determination method is2h heat time in103℃, and the Folin-Ciocalteu method was fit in determining total polyphenols’content in tea polyphenol products.83instant tea samples and48tea polyphenol product samples of different varieties or categories were collected from different manufactuers as research objects, it was tested that the component content of all samples according to national standards or methods built according to experiments. In instant tea, the content of different component was: moisture2.16%～10.37%with average4.42%; tea polyphenols5.46%～49.45%with average26.94%; gallic acid(GA)0%～1.49%with average0.54%; caffeine0.28%～12.42%with average6.08%; EGCG0%～13.99%with average4.47%; EC0%～3.32%with average1.26%; ECG0.04%-6.79%with average1.80%. According to the component analysis of tea polyphenol products, content of moisture is1.87%～7.19%with average3.58%, content of total polyphenols is30.08%～94.19%with average68.90%, content of GA is0.05%～1.96%with average0.62%, content of caffeine is0%～24.06%with average5.10%, content of EGCG is6.65%～55.15%with average29.19%, content of EC is1.45%～10.50%with average5.37%; content of ECG is1.36%～17.05%with average7.62%。NIR spectrum of4000～10000cm-1was obtained by Fourier transform NIR spectrometer(Buchi Labortechnik AG company, Version:N-200) with20g even samples by scatterd reflection, combined with data obtained by chemical analysis, research on NIR rapid measurement method was done. The results showed that, Q values of instant tea models were:moisture0.8838, total polyphenols0.7920, GA0.8321, caffeine0.8336, EGCG0.7008, EC0.7298, ECG0.6166. According to relativity analysis of true value and predicted value, correlation coefficients were:moisture0.9848, total polyphenols0.9727, GA0.8016, caffeine0.9814, EGCG0.9231, EC0.8552, ECG0.8052. Q values of tea polyphenol product models were:moisture0.8428, total polyphenols0.5309, GA0.7393, caffeine0.7560, EGCG0.5762, EC0.6101, ECG0.7197. According to the contrast of ture value and predicted value, the correlation coefficients were:moisture0.9804, total polyphenols0.9627, GA0.7557, caffeine0.9194, EGCG0.9495, EC0.7633, ECG0.9208.According to the analysis of average fingerprint, the discrimination of the variety of instant tea and the purity scope of tea polyphenol products was researched. The outer recognition accuracy of instant tea and tea polyphenol products was76.9%and84.6%respectively, and simpler classification of instant tea could obtain better recognition accuracy.NIR spectrum, combined with factor analysis and Fisher discriminant analysis, was also used in this discrimination. By this method, when considering instant tea, the recognition accuracy of back substitution was79.4%, meanwhile, the recognition accuracy of cross validation was69.1%. When considering tea polyphenol products, the recognition accuracy of back substitution was89.7%, meanwhile the recognition accuracy of cross validation was83.3%.When using the data of component content of instant tea to do Fisher discriminant analysis, the recognition accuracy of back substitution was92.6%, the recognition accuracy of the cross validation was89.7%, and the result was better than that using factor analysis prior. |
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