Multiscale interaction of Hericium coralloides polysaccharide with maize starch: Impact on structural properties and...

Regulating starch digestion to alleviate postprandial hyperglycemia is one of the core challenges in the field of nutrition. Edible mushroom polysaccharides have become highly promising natural starch modifiers due to their dual functions of modulating food structure and potentially inhibiting digestive enzyme activity. In this study, a coral-like Hericium erinaceus polysaccharide (HCP) with a unique β-(1 → 3)-galactan backbone and fucose/glucuronic acid side chains were selected to systematically investigate its multi-scale interactions with maize starch and the mechanism by which it regulates starch digestibility. Multi-scale characterization showed that HCP and maize starch formed an extensive hydrogen bonding network, which significantly altered starch crystallinity, increased the storage modulus of the gel to 1001 Pa (with 0.5% HCP), and markedly enhanced water retention. In vitro digestion experiments demonstrated that HCP inhibited starch hydrolysis by forming a physical barrier to restrict enzyme access and by strongly binding to α-glucosidase to suppress its activity, reducing rapidly digestible starch content from 68.3% to 41.5% while increasing slowly digestible starch and resistant starch to 32.7% and 25.8%, respectively. Molecular dynamics simulations further revealed that HCP can act as an effective and specific ligand for α-glucosidase, with a binding free energy (-104.80 kcal/mol) significantly stronger than that of maize starch (-42.88 kcal/mol), demonstrating excellent binding strength and conformational regulatory capacity. Moreover, HCP can self-assemble with starch to form stable composite aggregates. These findings provide a theoretical foundation for the rational design of functional foods with a low glycemic index based on polysaccharide-starch interactions.