Modulating the multiscale structure and digestibility of OSA starch by phenolic acid substituents and heating process.

The synergistic effect of methoxy-to-phenolic hydroxyl group ratios in phenolic acid and heat treatment on modified starch structures and underlying mechanism remain unexplored. This study aimed to elucidate the effects of octenyl succinic anhydride (OSA) starch (OR) multiscale structure and digestive properties by constructing complexes between OR and caffeic acid (CA), ferulic acid (FA), and sinapic acid (SA) at 25 °C/90 °C. Results indicated that OR-CA was more ordered among the complexes prepared at 25 °C. Methoxy groups enhanced phenolic acid reactivity, and OR was most stably bound to SA. The increased phenolic acid content at 90 °C promoted the formation of V-type complexes through hydrophobic interactions, where the resistant starch content of the complexes containing SA was 36.90 %. Phenolic acids synergistically reduced digestibility by inhibiting amylase activity or forming densely ordered crystalline structures with OR. The discovery enables targeted design of anti-obesity starchy foods by leveraging phenolic-starch complexes.