Differential characteristics of chemical composition, fermentation metabolites and antioxidant effects of polysaccharides from Eurotium Cristatum and Fu-brick tea.

Fu-brick tea (FBT) is predominately fermented by Eurotium Cristatum, FBT polysaccharides (FTPs) and Eurotium Cristatum extracellular polysaccharides (ECPs) are the main active substances in FBT and Eurotium Cristatum, respectively. FTPs was shown to exhibit higher levels of uronic acids, proteins, and polyphenols as compared to ECPs (p < 0.05), contributing to the superior antioxidant activity observed in FTPs. Additionally, FTPs had better water solubility and thermal stability than ECPs. Interestingly, in vitro digestive simulation revealed that FTPs and ECPs resist digestion in the stomach and small intestine. Excitingly, utilizing in vitro fermentation with feces from healthy individuals and type 2 diabetes mellitus (T2DM) patients demonstrated that FTPs and ECPs promote the production of SCFAs. Still, FTPs resulted in greater SCFAs contents than ECPs (p < 0.05). Moreover, FTPs and ECPs fermentation by T2DM patients' fecal microbiota affected different metabolomic pathways. Our findings suggested that FTPs holds great promise for application in functional foods.