In vitro digestion, fecal fermentation, and gut bacteria regulation of brown rice gel prepared from rice slurry backfilled with rice bran

Abstract

Whole-grain brown rice might regulate obesity, and the specific mechanism could be referenced through in vitro digestion and fermentation. This study aimed to investigate the gut bacteria-modifying of brown rice gel (BRG) which was prepared by backfilled rice slurry with rice bran. Due to the existence of rice bran, compared with rice gel, BRG could inhibit starch expansion, reduce viscosity and breakdown, increase short-term aging degree, and then reduce the glycemic index of in vitro digestion from 85.79 to 72.76. Gas chromatography-mass spectrometry showed that BRG promoted the production of short-chain fatty acids after 24 h of fermentation, and the contents of acetic acid, propionic acid, and butyric acid increased to 10.84 ± 0.16, 2.86 ± 0.05, 2.68 ± 0.13 μg/mL ( p < 0.05), respectively. After fermentation for 0, 6, 12, and 24 h, 16S rRNA sequencing revealed that BRG could improve the uniformity of gut microbial community and reduce its diversity, but had little effect on the richness. Notably, BRG could regulate the relative abundance of gut bacteria. At the phylum level, the ratio of Firmicutes/Bacteroidetes (F/B) decreased, which might be associated with prevention of obesity. At the genus level, it increased the beneficial bacteria Bifidobacterium and reduced the pernicious bacteria Bilophila . The results will facilitate the application of whole-grain brown rice in gel-based functional foods. • Brown rice gel (BRG) reduced the glycemic index compared with rice gel. • BRG promoted the SCFAs and decreased the pH. • BRG did not change the richness of gut microbiota. • BRG regulated the relative abundance of beneficial and pernicious gut bacteria. • BRG had a potential prebiotic activity.