Bioactivity and probiotic potential of bound polyphenols in insoluble and soluble dietary fibers from mango peel during in vitro digestion and fecal fermentation.

The bound phenolics (BPs) in dietary fiber (DF) form a natural delivery system due to fiber indigestibility, yet their gastrointestinal release kinetics and role in DF-mediated gut microbiota regulation remain unclear. This study extracted soluble and insoluble DF from mango peel to systematically investigate BPs content and composition, gastrointestinal release patterns, and microbiota-modulating effects. Results revealed BPs content of 15.65 ± 0.77 mg GAE/g DW and 23.44 ± 0.83 mg GAE/g DW in soluble and insoluble DF respectively, primarily composed of principally gallic acid, ellagic acid, and mangiferin, demonstrating sustained-release characteristics during colonic fermentation. Integrated analysis using gas chromatography and 16S rRNA sequencing indicated that BPs attached to mango peel DF promoted beneficial bacterial proliferation while enhancing short-chain fatty acids (SCFAs) production, thereby amplifying the prebiotic activity of DF. These findings establish BPs as crucial functional components in mango peel DF, highlighting the necessity for prioritized BPs preservation during high-value utilization of related by-products.