Rapid Determination of Three Catechin Components in Crude Pu-erh Tea by Near Infrared Spectroscopy
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Abstract:
In order to achieve rapid detection of the catechin content in crude Pu-erh tea, high performance liquid chromatography (HPLC) was used to determine the contents of three catechin monomers, namely, epigallocatechin gallate (EGCG), epigallocatechin (EGC), and gallic acid (GA), in 50 crude Pu-erh tea samples, and the partial least squares models (PLS) were also established to predict the contents of these catechins by combining the near infrared spectra (NIRS) of the samples. The established models were then verified. The experimental results showed that the coefficient of determination (R2) values of the models for EGCG, EGC, and GA models were 99.99%, 99.99%, and 99.92%, respectively. The values of root mean square error of calibration (RMSEC) for EGCG, EGC, and GA were 0.17, 0.15, and 0.10, respectively, and the corresponding relative standard deviation (RSD) values were 0.19%, 0.27%, and 0.56%, respectively. The results of external validation indicated that the mean absolute errors between the predicted values and actual values of the three models for catechin monomer contents were 0.13, 0.12, and 0.07, respectively, and the mean relative errors were 0.17, 0.25, and 0.45, respectively. The experimental results show that the near infrared analysis model established in this study has high prediction accuracy and stability, and has potential application value in rapid detection of catechins in crude Pu-erh tea.
