Mass spectrometry-based metabolomics and chemometric analysis of Pu-erh teas of various origins

Pu-erh tea is one of the most popular tea beverages in China. Storage time, fermentation process and origin of production affect quality and price of Pu-erh teas. High resolution mass spectrometry-based metabolomics approach, NIR combined with chemometric analysis were used to profile water soluble metabolites from raw Bingdao Pu-erh teas stored for 1-10 years and teas from various production sites. Year prediction models with good rate of recognition were established using partial least squares analysis and factor analysis. 38 characteristic compounds were identified that can be used to distinguish length of storage of Pu-erh teas. 19 characteristic compounds were found that can be used to differentiate raw and ripened teas. Cluster analysis of Pu-erh teas from different sites showed correlation between geographical distribution of the sites and composition of the water extracts. The research provides guidance for discrimination of Pu-erh teas and helps establish a healthy tea market.