Conformational and Rheological Changes of Hericium erinaceus Polysaccharides Driven by Molecular Weight Reduction and Their Impact on Prebiotic Effects

Hericium erinaceus polysaccharide was degraded using microwave-assisted enzymatic hydrolysis to obtain four gradient molecular weight fractions (HePs). This study investigated the effects of molecular weight on their structural, rheological, and prebiotic properties. The reduction in molecular weight preserved the monosaccharide composition, functional groups, and residue types but significantly decreased their apparent viscosity and converted spatial conformations from compact and rigid triple-helix structures into flexible random coils. All HePs resisted in vitro gastrointestinal digestion and were utilized by gut microbiota. HePs increased the relative abundance of short-chain fatty acid-producing bacteria such as Megamonas, Megasphaera, Bifidobacterium, and Ligilactobacillus. The upregulation effects of HePs on the above intestinal microbiota and short-chain fatty acids were negatively correlated with molecular weight. Molecular weight may affect the modulatory effects of HePs on the dominant intestinal microbiota, functional enzyme expression, and microbial metabolic pathways. These findings may provide a research basis for the development of HePs prebiotic products.