The release patterns and potential prebiotic characteristics of soluble and insoluble dietary fiber-bound polyphenols from pinot noir grape pomace in vitro digestion and fermentation

The bioactive substances abundant in grape pomace, particularly dietary fiber and polyphenols, exhibit prebiotic effects in the gut. The soluble dietary fiber and insoluble dietary fiber from the Pinot noir grape pomace were subjected to <i>in vitro</i> simulated digestion and colonic fermentation. The study found that bound polyphenols predominantly released during colon fermentation and exerted powerful antioxidant activities. The capabilities of SDF were superior to those of IDF in several aspects: it more effectively released total phenols and flavonoids, scavenged ABTS and hydroxyl radicals, inhibited α-glucosidase and lipase, regulated intestinal pH, and generated short-chain fatty acids. IDF enriched the diversity of the gut microbiota. Together, SDF and IDF reduced the F/B value, promoted beneficial bacteria, inhibited harmful bacteria, activated metabolic pathways for vitamin B6, ascorbate, and aldarate, and enhanced lipopolysaccharide and folate biosynthesis. These findings provide a basis for the development of dietary fiber in grape pomace as a functional food.