Chewing behavior and bolus particle size of rice influence carbohydrate digestion and gut microbiome metabolism in vitro
Zhen Liu, Ciarán G. Forde, Markus Stieger, Josep Rubert
Abstract
The size of ingested bolus particles and their surface area affect how accessible the substrates are to digestive enzymes and the gut microbiota. This study aimed to investigate the impact of oral breakdown of rice on the human gut microbiota in vitro. Three rice varieties with different fiber contents were chewed in vivo, then subjected to in vitro digestion and fecal batch cultures. Increasing the number of chews per bite from 5 to 40 led to higher structural breakdown and more extensive early starch hydrolysis, resulting in up to 14 % increase in the degree of starch hydrolysis during in vitro digestion, and 26-47 % smaller rice bolus particles after in vitro digestion. Higher bile salt hydrolase activity and total short-chain fatty acid levels (5-13 %) were found in less chewed rice. Untargeted lipidomics highlighted that the number of chews influenced numerous metabolites beyond SCFA.