Despite its nutritional value, chestnut starch is limited by rapid digestion, highlighting the importance of ultrasound modification to enhance its properties. In this study, the mechanism associated with the ultrasonic pretreatment of chestnut starch–cyanidin-3-O-glucoside (CS-C3G) complexes was elucidated, and the optimal ultrasound conditions (500 W, 30 min) were determined using single-factor experiments. Ultrasonication significantly altered the starch properties ( p < 0.05), increasing the apparent amylose content, solubility, swelling power, and water/oil absorption while reducing the particle size. Compared with CS-C3G, the ultrasonicated complex (UCS-C3G) exhibited a denser morphology, crystalline transition from C-type to amorphous, and reduced short-range molecular order. UCS-C3G exhibited the lowest pasting parameters and gelatinization enthalpy (5.30 J/g), forming fragile gels that demonstrated resistance to aging. Molecular docking revealed a strong binding affinity (−7.3 kcal/mol) between C3G and amylose, but molecular dynamics simulations revealed that the interaction is dynamic and reversible; C3G completely detached from amylose after 80 ns, indicating transient complexation rather than static stability. Nevertheless, compared with CS-C3G, UCS-C3G displayed a significantly higher resistant starch content ( p < 0.05) and a lower hydrolysis rate, with enhanced apparent viscosity and gel stability. Notably, ultrasonic pretreatment facilitated C3G penetration by disrupting the physical structure, thereby synergistically modulating multiscale structures and functional properties and providing a strategy for the development of slow-digesting functional food ingredients.
Li et al. (Fri,) studied this question.