Mechanisms and effects of ozone-pullulanase treatment on multiscale structures and in vitro digestibility of rice...

To investigate the effects and underlying mechanisms of the combined ozone-pullulanase treatment on the structure and digestibility of rice starch, we applied ozone treatment followed by pullulanase modification for different durations. A significant reduction in starch digestibility was observed, and the glycemic index (GI) dropped from 89.75 to 67.07. Further analysis of the multiscale structural changes revealed that ozone treatment alone progressively disrupted the granular structure, diminished the A-type crystalline pattern, increased gel viscosity, and reduced the degree of polymerization. In contrast, subsequent pullulanase treatment induced a complete loss of granular morphology and enhanced gel elasticity, chain rearrangement, and redistribution, which increased the degree of polymerization. These results demonstrate that ozone pretreatment enhances the efficiency of pullulanase action and effectively reduces the in vitro digestibility of rice starch.