Effect of bound polyphenol removal on in vitro digestion and fermentation of Rosa roxburghii Tratt. dietary fiber

Dietary fiber (DF) is a crucial part of a healthy diet. However, the impacts of bound polyphenols (BPs) on the diversity of gut microbiota and the production of metabolites—such as short-chain fatty acids (SCFAs)—as regulated by DF during in vitro digestion and fermentation remain largely unclear. Here, we evaluated the effects of BP removal on the in vitro digestion and fermentation of DF derived from Rosa roxburghii Tratt. (RRT)—a medicinal and edible fruit. Using DF rich in BPs (RRT-DF) and dephenolic DF (RRT-dP-DF), changes in polyphenol content (PC) and antioxidant activity during digestion and fermentation were evaluated alongside fermentation parameters (pH and SCFAs), gut microbiota structure, and metabolome profiles. Polyphenol release from RRT-DF was limited during gastrointestinal digestion (4–6%) but increased significantly during fermentation (25–27%). The fermentation broth of RRT-DF exhibited a significantly higher antioxidant capacity than that of RRT-dP-DF. RRT-DF also displayed favorable prebiotic properties; BPs enhanced DF-mediated SCFA production, modulated gut bacterial composition, and promoted the metabolism of lipids/lipid molecules and organic acids and their derivatives. Overall, these findings advance understanding of the potential role of BPs in regulating the in vitro digestion and fermentation of RRT-DF. • BPs in RRT-DF boost antioxidant activity by 33% during colonic fermentation. • BPs elevate butyrate production by 6.8-fold, enhancing gut health. • BPs enrich beneficial bacteria that strongly correlate with antioxidant metabolites. • BP removal disrupts key microbe-metabolite interactions, reducing functionality.