Computer-controlled simulated gastrointestinal digestion changes in vitro fermentation kinetics, microbial community, and short-chain fatty acid production of fiber-rich ingredients

Dietary fibers (DF) are well-established prebiotics that modulate gut microbiota and enhance host health. Nevertheless, how previous gastric-small intestinal digestion of DF impacts microbiota and metabolites during fermentation remains poorly understood. This study investigated the effects of pre-digestion, using a computer-controlled simulated digestion system (CCSDS) that mimics in vivo gastrointestinal conditions, on the fermentation kinetics, microbial community, and short-chain fatty acid (SCFA) production of six fiber-rich ingredients [sugar beet pulp (SBP), wheat bran (WB), corn DDGS (DDGS), soybean hull (SH), rice bran (RB), and alfalfa meal (AM)], followed an <em>in vitro</em> fecal fermentation was employed. Results showed that simulated digestion reshaped DF fermentation kinetics, with gas production decreased for WB, but increased for SH, SBP, DDGS, and AM (<em>P</em> &lt; 0.05). SCFA profiles diverged significantly, reflected by SBP and DDGS residues increased butyrate production, whereas WB and RB residues reduced acetate and propionate yields (<em>P</em> &lt; 0.05). α-diversity (Sobs, Chao1, and Ace indexes) increased in residues of WB, SBP, and AM (<em>P</em> &lt; 0.05). PCoA analysis confirmed distinct clustering between ingredients and residues (<em>P</em> &lt; 0.01), with residues increasing the abundance of fiber-degrading and SCFA-producing genera (e.g., <em>Prevotellaceae_NK3B31_group </em>in WB residues, <em>Treponema</em> in DDGS residues, <em>Lysinibacillus</em> in RB, SBP, and AM residues). These findings demonstrate that pre-digestion critically modifies DF fermentation and microbiota interactions, providing valuable insights for the selection of DF in diet formulations and enhancing our understanding of their beneficial effects on gut health.