Nutrients reach the body through the food delivery system, interacting with intestinal mucus and gut microbiota for effective absorption. The purpose of this study was to investigate the possible interactions between soluble soy hull polysaccharide (SSHP), gut microbiota and mucin. The digestive environment of the porcine intestinal mucus was simulated, and the changes of the SSHP-mucin mixed system were monitored by shear rheology, interface measurement, scanning electron microscopy, particle size distribution, and microbial sequencing. First, based on scanning electron microscopy and particle size distribution, it was shown that the gut microbiota undergoes glycolysis in different mucus. The apparent viscosity and viscoelastic properties of the mucus during fermentation were then determined using shear rheology. Compared with the control and microwave-assisted citric acid extraction of soy hull polysaccharide (MCSP), the viscosity of microwave-assisted oxalic acid extraction of soy hull polysaccharide (MOSP) increased significantly (p < 0.05) at 24 h, and the thixotropy of all samples increased. The adsorption properties of mucin at the air-liquid interface were analyzed by the interfacial tension technique. As the fermentation time increased, the adsorption performance of the SSHP mucus increased, the interfacial tension decreased, and the expansion modulus increased. Moreover, according to high-throughput 16S rDNA sequencing analysis, the gut microbiota community structure changed significantly after ingestion of MCSP and MOSP, and the abundances of Bifidobacteriaceae and Lactobacillaceae increased to varying degrees. In summary, polysaccharides can be used by the intestinal flora to increase the viscosity and thixotropy of the mucus system, to increase the interfacial strength, and promote the proliferation of intestinal probiotics. This study provides useful insights for the potential application of SSHP.
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