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Abstract

To assess the impact of hydration kinetics of dried foodstuffs on their sensory property and release of functional molecules, it is necessary to be able to predict the temperature effect. Based on the dynamics of capillary flow in partially saturated porous media, a finite-element model is developed to directly predict the infiltration of water into dried food materials as a function of temperature. The transfer properties are derived from physically based constitutive relationships of water adsorption and permeation. This is in contrast to the semiempirically fitted transfer properties often used in the heat- and mass-transfer models of foods based on Fick's diffusion theory. Rehydration of green tea at different temperatures has been measured using the NMR method. The rehydration process also has been simulated using the capillary model, and the predictions are in good agreement with experimental data.