Sono‐Hydro Priming of Proso Millet ( Panicum miliaceum ): Effect on Soaking Kinetics, Hydration Behavior and Surface Morphology

Conventional hydration of cereal grains is inherently time‐intensive, whereas to counter this, soaking at elevated temperatures, although faster, may also lead to enhanced microbial proliferation and higher solid leaching. To overcome these limitations, ultrasound (US) was employed as a non‐thermal intensification technique to accelerate the hydration kinetics and improve the imbibition capacity of proso millet ( Panicum miliaceum ). The US‐assisted hydration (UAH) experiments were conducted at varying amplitudes (30%–70%) and treatment durations (10–30 min). The equilibrium moisture content (EMC) exhibited a positive correlation with both ultrasound amplitude and treatment time. Scanning electron microscopy (SEM) revealed distinct surface etching on the seed coat, attributed to the generation of reactive species during acoustic cavitation. This microstructural modification increased the surface roughness and hydrophilicity of the grain, as evidenced by a 44.12% reduction in the water contact angle, thereby enhancing the imbibition rate. Both conventional and UAH followed a downward concave‐shaped moisture uptake pattern. The maximum increase in EMC (14.33%) and a corresponding reduction in total hydration time (79.2%) was achieved under the treatment condition of 70% amplitude for 30 min. The hydration process was found to proceed in two distinct phases: an initial rapid phase corresponding to surface wetting through capillarity and a subsequent slower phase dominated by internal diffusion. Among the kinetic models evaluated, the order of goodness of fit was found to be Weibull < Lewis first order < Page < Peleg. Furthermore, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were performed to elucidate the interrelationships among the kinetic parameters, revealing strong associations between k₂ , k₄ , and among α , β , and n .