Differential Effects of Glutelin-to-Globulin Ratios on the Retrogradation Behavior of Rice Starch

Glutelin and globulin in protein body II (PB-II) are the major components of rice protein. This work systematically investigated how varying glutelin-to-globulin ratios (1:0, 2:1, 1:1, 1:2, 0:1) influenced rice starch retrogradation. Glutelin showed strong anti-retrogradation performance, achieving a 54.0% reduction in retrogradation enthalpy (ΔH) and 27.3% inhibition of crystallinity, likely owing to its hydrogen-bonding capacity and network-forming properties. In comparison, globulin increased moisture retention, possibly through competitive hydration, but showed only 7.6% inhibition of crystallinity. Notably, based on ΔH, the 1:1 (w/w) glutelin–globulin blend achieved 83.0% retrogradation inhibition efficiency, comparable to glutelin alone, despite containing half the glutelin content. This phenomenon may result from their different functional roles: glutelin may serve as a structural scaffold, while globulin may act as a water-modulating agent. Overall, glutelin shows superior anti-retrogradation performance to globulin, and the glutelin-to-globulin ratio strongly influences this anti-retrogradation behavior. These results suggest that modulating protein composition may potentially improve storage quality and extend the shelf life of rice starch products.