LAUSR

Abstract The aim of this work was to solve a model regarding water loss and soluble solids gain during osmotic dehydration (OD), considering real shape and solid shrinkage along the process. As an experimental case of study, OD of tomatoes halves of semi-ellipsoidal shape in hypertonic solutions of sucrose and NaCl, was selected. OD assays were carried out in two hypertonic solutions (soluble solids 35% and 50% (w/w)) with 1:8 (w/w) tomato/solution at 25 °C. Comsol Multiphysics coupled with Matlab computational tools were used for solving model's equations applying finite elements method and optimization algorithms for parameter estimation. Effective diffusion coefficients and water to soluble solids total mass flux ratios were determined. Diffusion coefficients resulted smaller than those for a rigid solid and are independent of the solids geometry and contraction. Water to soluble solids flux ratio was bigger than 1 and increased with the osmotic solution concentration and solid shrinkage.