Abstract: In this study, mass spectrometry-based metabolomics was used to analyze the chemical composition of raw Pu-erh tea made from the fresh leaves of the large-leafed tea cultivar picked from an abandoned tea plantation where manual picking and management have been resumed. It was found that manual picking and management resulted in a significant increase in the contents of theanine, glutamic acid, both responsible for the fresh and brisk taste, and total amino acids, and also increased the contents of umami-enhancing alkaloids and catechins responsible for the sweet aftertaste of Pu-erh tea, thereby improving the taste and quality of the tea. Chemical analysis showed that manual management did not significantly change the total polyphenol content or antioxidant capacity outside cells of the tea. However, cytotoxicity and antioxidant activity tests showed that the inhibitory effect on the proliferation of cancer cells (U2OS) and the antioxidant capacity inside cells were enhanced by manual management. Manual picking and management had little effect on the contents of inorganic ions, total phenols or caffeine of the tea, indicating manual intervention had no significant influence on the physiological status of the plants. This study may provide a theoretical basis for the study of the quality of raw Pu-erh tea.

Key words: raw Pu-erh tea; metabolomics; liquid chromatography-mass spectrometry; compositional analysis; manual picking and management