Abstract
Partridge tea (Mallotus oblongifolius (Miq.) Müll.Arg.) is a local characteristic tea in Hainan, the southernmost province of China, and the quality of partridge tea may be affected by the producing areas. In this study, stable isotope and targeted metabolomics combined chemometrics were used as potential tools for analyzing and identifying partridge tea from different origins. Elemental analysis—stable isotope ratio mass spectrometer and liquid chromatography-tandem mass spectrometrywas used to analyze the characteristics of C/N/O/H stable isotopes and 54 chemical components, including polyphenols and alkaloids in partridge tea samples from four regions in Hainan (Wanning, Wenchang, Sanya and Baoting). The results showed that there were significant differences in the stable isotope ratios and polyphenol and alkaloid contents of partridge tea from different origins, and both could accurately classify partridge tea from different origins. The correct separation and clustering of the samples were observed by principal component analysis and the cross-validated Q2 values by orthogonal partial least squares discriminant analysis (OPLS-DA) were 0.949 (based on stable isotope) and 0.974 (based on polyphenol and alkaloid), respectively. Potential significance indicators for origin identification were screened out by OPLS-DA and random forest algorithm, including three stable isotopes (δ13C, δ D, and δ18O) and four polyphenols (luteolin, protocatechuic acid, astragalin, and naringenin). This study can provide a preliminary guide for the origin identification of Hainan partridge tea.
Highlights
Tea is one of the most popular non-alcoholic beverages consumed by more than twothirds of the world’s population because of its attractive aroma, refreshing mouth feel, and multiple health benefits [1]
It could be observed that the 2D scores plot of Principal component component analysis analysis (PCA) divided the samples into four independent clusters, representing the partridge tea samples derived from SY, WN, WC, and BT, indicating that there were significant differences in the polyphenol and alkaloid metabolism spectra of partridge tea from different origins, and the samples could be naturally grouped according to their metabolite characteristics, which was consistent with the result obtained by hierarchicalclustering clusteringanalysis analysis (HCA) before
The C/N/O/H stable isotope ratios and polyphenol and alkaloid contents of partridge tea from SY, WN, WC, and BT regions in Hainan Province of China were determined, and these characteristics were used for the first time to identify the geographic origin of partridge tea
Summary
Tea is one of the most popular non-alcoholic beverages consumed by more than twothirds of the world’s population because of its attractive aroma, refreshing mouth feel, and multiple health benefits [1]. Green tea in various regions of China [2,8,9] This technique is primarily based on the ratio of stable C/N/O/H isotopes relative to the geographic origin and plant metabolism. Methods based on stable isotope ratio mass spectrometry (IRMS) and metabolomics have not been used to determine the correct geographic origin of partridge tea from different origins in Hainan. IRMS and liquid chromatographytandem mass spectrometry (LC-MS/MS) were used to analyze the stable isotope ratios and the contents of polyphenols and alkaloids in partridge tea, and in combination with chemometrics, to analyze the differences and identify the partridge tea from different geographical origins.
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