Synergistic effects of endogenous protein components and starch molecular structure on physicochemical, rheological...

Developing rice cultivars with low-glutelin and high-resistant starch is beneficial for health management in diabetes and chronic kidney disease. This study systematically investigated the structural, physicochemical and digestive properties of four isogenic rice mutant cultivars with graduated prolamin-to-glutelin (P/G) ratios and identical macronutrient compositions. Molecular structure analysis revealed similar whole starch molecular size distributions but different amylopectin chain length distributions among samples with varying P/G ratios. The isolated starch with shorter and fewer amylopectin short-medium chains exhibited more disordered crystalline structures, resulting in reduced gelatinization enthalpies, peak viscosities and gel viscoelasticity, thereby promoting enzymatic hydrolysis. Critically, the prolamin-rich matrix exhibits stronger hydrophobic interactions, which inhibit starch granule swelling and promote starch-starch interactions, resulting in a stronger gel structure and resistant starch content increases by 8.73 % to 13.48 %. These findings reveal new insights into cultivating functional rice tailored for patients with diabetes and kidney disease by regulating the prolamin-to-glutelin ratios.