Description:
<jats:title>Abstract</jats:title><jats:sec><jats:label /><jats:p>Rice hydration is the main unit operation in both parboiled and germinated rice industries. Despite its importance, few studies investigate its basic principles, related to phenomena and physicochemical rice changes during hydration step in each one of these processes. Aiming to contribute to these processes, was a mass transfer kinetic study associated to identification of moisture incorporation mechanisms and alterations in the starch during the paddy rice hydration. The observed mass transfer in the process was directly influenced by the system temperature, showing changes in absorption capacity over time. A tracer pigment added to the hydration medium revealed that the mechanism of the water entrance into the grain was through diffusion through the grain coating and by capillarity through the fissures. The thermal analysis and scanning electron micrographs (SEM) showed that hydration at 55 and 65°C presented partial and total gelatinization of the starch, respectively. The models addressed allowed describing the moisture gain for various thermal conditions. The generalized model obtained was able to predict the experimental moisture at any process time for any of the investigated temperatures with a 5% maximum deviation. This research contributes significantly to the understanding of the phenomena involved in rice hydration, aiding in the development of operational parameters; they also point to a mathematical model that is able to represent the experimental data in a manner that is simple, quick, and inexpensive, particularly for industrial use.</jats:p></jats:sec><jats:sec><jats:title>Practical Applications</jats:title><jats:p>This study presents a paramount contribution to the time–temperature binomial establishment in the rice hydration process, since it provides as a process tool, the kinetic hydration model of moisture incorporation, as well as reveals the alterations in the grain microstructure. The discoveries can boost industries that process paddy rice, especially those located in poorer areas that lack knowledge and information, helping to improve operating conditions. Such a context justifies the investigation of models that may be easily applied, perform well, and are inexpensive, such as is the model presented in the present work, which may be applied by industries to monitor and also specify optimal operation conditions.</jats:p></jats:sec>