A DIFFUSION MODEL WITH CONCENTRATION-DEPENDENT EFFECTIVE DIFFUSIVITY DURING THE VACUUM DRYING OF CARROT

摘要

The carrot kinetics of vacuum drying is studied using freezing pre-treatmentrnprocess for the food samples. The objective the pre-treatment is to modify thernthermophysical properties of raw material in order to improve the mass transferrnduring dehydration and rehydration of the final product. Pressure effects arernanalyzed (15 and 28 kPa absolute), heating temperature (50, 60 and 70 °C) on therndrying rate. Mass transfer phenomena studies were carried out using a modelrnbased on the Flick second law and considering the effective diffusion coefficientrnas an exponential function of the moisture concentration. The model was solvedrnnumerically for slab sample and a moisture transport in one direction.