Evaluation of water diffusivity in wheat hydration (Triticum spp): Isothermal and periodic operation

In this study, kinetic and diffusivity of water in the isothermal and periodic hydration of the BRS220 wheat cultivar, were investigated. The isothermal hydration tests were carried out for 600 min at 30, 40, 50, and 60 °C. The periodic operation experiments were performed considering the temperature of 40 °C. The periodic hydration of 20 °C amplitude, which was performed in 40‐min periods, was more efficient in comparison with the isothermal at 40 °C, since the former presented 84% moisture absorption in Phase I of the hydration, and increased the diffusion coefficient (D) in 26.7%. The diffusion model and the generalized equation presented good fit to the experimental data, with p values from 1.28 to 3.04% and RMSE from 5.28 × 10−2 to 12.5 × 10−2%. The hydration tests with colorants indicated that the water enters the wheat grain through the micropyle and then through the grain pericarp, by capillarity. Practical applications This research presents kinetics and water diffusivity in isothermal and periodic hydration of wheat. Periodic hydration is efficient compared to isothermal hydration due to the increased water absorption rate in the grain. This influences directly the reduction of time and energy savings of the industrial process. The results presented can be used by industries interested in increasing the efficiency of grain processing with lower energy expenditure. In addition, this work reveals the water uptake behavior inside the wheat grain, which until now has not been in depth presented in previous literature.