Chlorogenic acid modulates configuration-dependent structural organization, lipid oxidation, and digestion in aqueous starch-unsaturated fatty acid systems.

Starch-based food systems are widely consumed worldwide, yet their rapid digestibility and the oxidative instability of incorporated unsaturated lipids remain major challenges for improving nutritional quality and storage stability. In this study, a processing-driven ternary assembly strategy was developed by constructing starch-unsaturated fatty acid (UFA)-chlorogenic acid (CGA) systems. Oleic acid (OA) and its geometric isomer elaidic acid (EA) were employed to elucidate how UFA molecular geometry influences ternary structure and functional outcomes. Multiscale structural analyses showed that UFAs governed amylose helix inclusion and crystalline organization, while CGA participated in intermolecular interactions within the ternary system, potentially reinforcing interfacial organization and contributing to supramolecular stabilization. Interactions among starch, UFAs, and CGA generated hierarchical structures that simultaneously restricted enzyme accessibility and reduced lipid exposure to oxidative environments. OA-based ternary complexes formed more compact assemblies with enhanced digestion resistance, whereas EA-containing systems exhibited looser structures and faster hydrolysis. Meanwhile, CGA suppressed lipid oxidation through preferential hydrogen atom transfer enabled by its lower OH bond dissociation enthalpy. Quantum chemical analysis further supported the molecular interaction mechanisms underlying ternary assembly. These findings provide a strategy for designing starch-based matrices with improved nutritional and oxidative stability.