Abstract: To obtain the rational water content of pu-erh tea for pile-fermentation, variations in the contents of main components of Pu-erh tea were systematically investigated and the process of pile fermentation was simulated under varying water contents. The results showed that at the end of pile fermentation, the contents of tea polyphenols, catechins, heaflavin, thearubigins and amino acids showed a downtrend while the contents of water-soluble sugar, theabrownins and theine appeared to increase. Different water contents of tea led to differences in the species of microorganisms involved in the fermentation process and pile temperature, which eventually affected the quality of tea significantly. In sensory evaluations, the products with 45% water content showed better quality.

Key words: Pu-erh tea, water content, pile-fermentation, chemical component