A phycocyanin-resveratrol-containing extrusion system modulates starch reassociation toward V-type ordering with reduced retrogradation and digestibility.

Starch retrogradation is governed by the reassociation and hierarchical ordering of starch chains during storage, which strongly influences both structural stability and digestive behavior. However, how exogenous components regulate the reassociation pathway of high-moisture extrusion (HME) starch and its relationship with digestibility remains poorly understood. In this study, a phycocyanin- and resveratrol-containing HME corn starch system was constructed to investigate its influence on short- and long-term retrogradation as well as starch digestion. The phycocyanin-resveratrol-containing formulation showed enhanced resistance to conventional retrogradation, with anti-retrogradation (AR) values reaching 19.67% and 12.77% after 1 and 21 days of storage, respectively. Structural analyses revealed that HME disrupted native starch structures and increased the tendency of starch matrices to undergo reassociation and B-type recrystallization during storage. The incorporation of the phycocyanin-resveratrol-containing formulation was associated with reduced double-helical reassociation and increased single-helical and V-type ordered structures during storage. Consequently, the starch system evolved toward less densely packed supramolecular assemblies with reduced gel reinforcement and suppressed long-term retrogradation. These structural transitions were accompanied by lower final hydrolysis extent and increased resistant starch (RS) content, suggesting that changes in starch reassociation behavior contributed to the concurrent modification of retrogradation and digestibility.