In vitro simulated digestion of and microbial characteristics in colonic fermentation of polysaccharides from four varieties of Tibetan tea.

Polysaccharides as a functional prebiotic have numerous activities such as regulating intestinal microorganisms and polysaccharide is one of the functional active components in tea has been known. In this study, we aimed to investigate the physicochemical characteristics of polysaccharides from four kinds of Tibetan teas at simulated digestion stages and the effect on the microbiota of fecal fermentation stages in vitro. The results revealed that Tibetan tea polysaccharides were partially digested during digestion. Additionally, during in vitro fecal microbial fermentation, Tibetan tea polysaccharides can promote the growth of some beneficial bacteria such as Bifidobacterium, Prevotella and Phascolarctobacterium to change the composition of intestinal microorganisms and promote the production of short-chain fatty acids (SCFAs). Finally, a strong correlation was found between the production of SCFAs and microorganisms including Bacteroides, Bifidobacterium and Lachnoclostridium. These results suggest that Tibetan tea polysaccharides could be developed as a prebiotic to regulate human gut microbiota.

Targeted and untargeted metabolomic analyses and biological activity of Tibetan tea.

Tibetan tea is not only a national product of geographical identity, but also a traditional beverage inherits Chinese tradition. This study evaluated the metabolic profiles and biological activity in four Tibetan teas. 83 non-volatile metabolites were identified as differentially expressed metabolites, including amino acids and their derivatives, phenolic acids, flavonoids, nucleotides and their derivatives, terpenes, alkaloids, organic acids, lipids and others. CC and 131 were rich in terpenoids and lipids. MZ contained the highest contents of amino acids and their derivatives, phenolic acids and flavonoids. 26 key volatile compounds were considered as odor-active compounds. MZ showed the highest level of antioxidant and hypoglycemic activity. Statistics analysis indicated that polyphenols, flavonoids and catechins were significantly correlated (|r| ≥ 0.7, P < 0.05) with biological activities. This study indicated significant differences in the metabolic profiles of various types of Tibetan tea, which provided a clear database for quality detection of Tibetan tea.