A crystalline starch model and anisotropic pressure field for MD simulation of starch-polyphenol interactions: Using...

Molecular dynamics (MD) simulations provide atomistic insights into starch-polyphenol interactions but are limited by simplistic models and difficult replication of mechanical processing. Consequently, a crystalline model of A-type starch featuring monoclinic unit cells with single-helical segments was established and an anisotropic pressure field was applied to simulate high-pressure homogenization (HPH) regulating the interaction between starch and cyanidin-3-O-glucoside (C3G). The dynamic formation of starch-C3G complexes under 0.1-1000 MPa at 353.15 K, along with the interaction forces and sites, was investigated. Results showed that HPH increased starch chain flexibility, and phenolic hydroxyl groups on C3G (donors) preferentially formed hydrogen bonds with pyranose ring oxygen atoms on starch (acceptor) chains, regulated through HPH-induced structural changes in starch. 200 MPa disrupted starch crystalline structure, generating "pocket-like" conformations that facilitate C3G intercalation, with enhancing hydrogen bonding in starch-C3G by 25%. Higher pressures (400 MPa) increased starch-C3G contact but limited hydrogen bonding. At 1000 MPa, excessive structural damage reduced C3G binding affinity and hydrogen bonding capacity by promoting C3G self-aggregation and forming inter-helical "channels". This study validates experimental observations, reveals how pressure-induced conformational changes regulate interactions, and offers a generalizable computational strategy for designing and optimizing functional starch-based delivery systems.