Optimization of moisture content and duration in low-speed rotational thermostatic tempering for enhanced physicochemical properties of indica rice flour

In this study, a novel low-speed rotational thermostatic tempering (LSRTT) technique was applied to indica rice for dynamic tempering. The effects of tempering moisture content (20 %–28 %) and duration (2–12 h) on the physicochemical properties of semi-dry-milled indica rice flour were systematically investigated. Optimal parameters were determined by analyzing damaged starch content and particle size distribution under varying moisture levels, alongside measurements of water distribution, microstructure, and shear texture across tempering durations through comprehensive analysis. Through comprehensive analyses including damaged starch content, particle size, hydration properties, gelatinization behaviors, thermal properties, X-ray diffraction (XRD), and rheological properties, the optimal parameters were identified as 26 % moisture content with 10 h tempering, yielding flour quality comparable to wet-processed. Remarkably, a shortened 2 h protocol at 26 % moisture achieved enhanced hydration capacity and shear stability, demonstrating the potential for energy-efficient processing. These findings provode theoretical and practical foundations for industrial-scale production of high-quality indica rice flour.