Covalent Interaction Between High-Amylose Corn Starch and Ferulic Acid: Reshaping of the Structure

This study investigated the covalent grafting of ferulic acid (FA) onto high-amylose corn starch (HACS) through controlled moist heat treatment as a strategy to regulate starch structure and digestibility. Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR) analyses confirmed the formation of ester linkages between HACS and FA. Scanning electron microscopy (SEM) revealed that FA grafting induced a rougher granule surface and increased porosity, while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicated altered gelatinization behavior and thermal stability. In vitro digestion analysis showed that the rapidly digestible starch content decreased from 23% to 15%, whereas the resistant starch (RS) content increased to 48% after FA grafting. Molecular docking suggested that FA could interact with α-amylase and that covalent modification may reduce enzyme accessibility to starch chains, thereby limiting starch hydrolysis. These findings demonstrate that FA grafting effectively reshapes the structural and digestive properties of HACS and provides a promising approach for developing resistant starch-rich functional food ingredients.