Latin American applied research
versión impresa ISSN 0327-0793
Many processes in food technology involve water migration from or into the processed product. Modeling of food water migration knowledge could result speeding up the processes, improving the quality of final products, and reducing energy costs. A mathematical formulation for mass transfer during drying and hydration of a porous solid sphere with volume change was developed in terms of the diffusion equation. The present model also provides an analytical expression for the ariation of water diffusivity with moisture content based on a simple relationship between the activation energy for diffusion and sorption energy. The non-linear diffusion equation was solved numerically, moisture profiles, the kinetics curves for drying and hydration and the moisture concentration dependence of diffusivity coefficient were calculated. Marked differences were observed in the moisture profiles for drying and hydration. The kinetic curves of both processes are strongly dependent on the range of moisture tested. Moisture diffusivity falls drastically at low moisture contents.
Palabras llave : Shrinking; Hydration; Swelling; Drying; Moisture Fiffusivity.