The mellow and thick taste is a unique characteristic of pu-erh ripe tea infusion, and it is closely related to the chemical composition of pu-erh ripe tea, which is less studied. This paper clarifies and compares the chemical composition of pu-erh ripe tea to that of the raw materials of sun-dried green tea, and uses membrane separation technology to separate pu-erh ripe tea into the rejection liquid and the filtration liquid. The results show that microorganisms transformed most physicochemical components, except caffeine, during the pile fermentation. It was found that total tea polyphenols, soluble proteins, total soluble sugars, theabrownin, and galloylated catechins became enriched in the rejection liquid, and the rejection liquid showed a more obvious mellow and thick characteristic. Taste interactions between crude protein, crude polysaccharide, and theabrownin were determined. They illustrated that the mellow and thick taste of pu-erh ripe tea with the addition of theabrownin increased from 4.45 to 5.13. It is of great significance to explore the chemical basis of the mellow and thick taste in pu-erh tea for guiding the pu-erh tea production process and for improving the quality of pu-erh tea.
Keywords: mellow and thick; pu−erh ripe tea; taste interaction; theabrownins; ultrafiltration.