Path-dependent effects of ultrasonic and annealing treatments on the multiscale structure and functionality of rice flour for savory rice pudding (wa gui) applications.

Physical modification provides a sustainable strategy for tailoring rice flour functionality; however, the role of treatment sequence in dual physical modification remains insufficiently understood. This study investigated the sequence-dependent effects of ultrasonic treatment (UT) and annealing (ANN) on the multiscale structure, hydration behavior, pasting properties, water dynamics, rheological performance, and gel-forming ability of indica rice flour from Taichung Sen 17. Savory rice pudding (wa gui) was further used as a proof-of-concept application model. The ANN-UT sequence caused the greatest structural disruption, as indicated by the lowest median particle size (D50 = 8.83 μm), relative crystallinity (15.23%), gelatinization enthalpy (0.25 J/g), peak viscosity (2068.66 cP), and final viscosity (3392.33 cP). These changes were accompanied by restricted swelling, higher water mobility, and weaker gel formation. On the contrary, the UT-ANN sequence retained greater structural continuity and reassociation capacity, as reflected by higher D50 (10.43 μm), relative crystallinity (16.15%), gelatinization enthalpy (0.65 J/g), peak viscosity (4273.66 cP), and final viscosity (6913 cP). UT-ANN also promoted stronger water confinement and firmer wa gui gel formation. These findings indicate that UT-ANN and ANN-UT represent distinct path-dependent routes of modification rather than interchangeable dual treatments. Sequence control may therefore provide a non-chemical strategy for designing rice-based ingredients with tunable hydration, pasting, and gel-forming properties. Further molecular-level characterization and validation of applications are required to confirm the structural basis and practical feasibility of this approach.