Microwave treatment modulates in vitro dynamic gastrointestinal migration of sorghum polyphenols and influences gut microbiota metabolism.

Gastrointestinal digestion is indispensable for the utilization of polyphenols from the diet. Polyphenol migration in the gastrointestinal tract, potential antioxidant activity, colonic accumulation, and regulation of short-chain fatty acids (SCFAs) by polyphenols were systematically explored in steamed sorghum (NorS) and microwaved steamed-sorghum (Mic-S). Relatively rapid gastric emptying and fragmented chyme of Mic-S liberated higher polyphenols (8.06 mg GAE/g DW) and antioxidant activity in the intestinal supernatant. Compared with the stomach, the bioaccessibility of intestinal polyphenols was significantly higher. Flavones, isoflavones, and flavanones were enriched in intestinal supernatant of Mic-S, while chyme was richer in phenolic acids and flavone glycosides (o-glucoside and c-glucoside). Moreover, fecal fermentation revealed higher bioaccessibility in Mic-S, which was attributed to the lower-size chyme that facilitated the extensive metabolism of Bifidobacterium, Megamonas, and Segatella. The hydroxybenzoic, hydroxycinnamic, and monomeric flavones enriched in the colon were correlated with Bifidobacterium and Bacteroides. Additionally, these low-molecular polyphenols indirectly regulated the production of SCFAs through amino acid metabolism and glucose metabolism pathways. The above findings suggested the enhancing effect of microwave treatment on the gastrointestinal accessibility of food-derived polyphenols, and provided theoretical support for the development of grain foods related to precision nutrition and intestinal health.