Novel green method for ferulic acid-high-amylopectin corn starch covalent with enhanced stability and reduced digestibility

This study developed a green and food-safe method to covalently graft ferulic acid (FA) onto high-amylopectin corn starch (HAPCS) through heating (110 °C, vapour pressure 0.145 MPa, 60 min). Structural characterization using 1 H NMR and FTIR confirmed the formation of ester bonds between the hydroxyl group at the C6 position of starch and the carboxyl group of FA. The conjugates exhibited enhanced thermal stability (ΔH reduced from −2811.31 J/g to −1123.48 J/g), increased resistant starch content (from 4 % to 72 %), reduced digestibility (C∞ decreased from 78.68 % to 48.56 %), and a lower estimated glycemic index (eGI reduced from 75.12 to 61.56) compared to native and gelatinized starch (HAPCS-P). The reduced digestibility and glycemic response are primarily attributed to the structural changes induced by the covalent grafting of FA onto HAPCS. These changes increase the compactness and density of the starch matrix, restricting enzyme access to digestion sites and reducing the overall hydrolysis rate of starch. These findings highlight the potential of HAPCS-FA as a functional food ingredient for glycemic control. The method provides an eco-friendly, scalable approach to starch modification, paving the way for the development of starch-based materials with tailored nutritional and functional properties. • A novel green method for preparing HAPCS-FA covalent complexes was proposed. • An ester bond formed between the C6 hydroxyl of HAPCS and the carboxyl group of FA. • The covalent binding with FA significantly increased the thermal stability of HAPCS. • The in vitro digestibility and glycemic index of HAPCS-FA were significantly reduced.