A three-dimensional numerical simulation of the osmotic dehydration of mango and effect of freezing on the mass transfer rates

Abstract : A mathematical model is developed for the mass and heat transfer during osmotic dehydration process of mango cubes. The model was implemented in COMSOL Multiphysics. Mass balance equations for the transport of water and sucrose were established separately for intracellular and extracellular volumes taking into account transfer across the cell membrane. The mass transfer resulted in change of intracellular and extracellular volumes as well as overall shrinkage. Measurements showed that freezing of the fruit significantly reduced cell diameter and tortuosity for extracellular mass transfer, and increased the rate of water loss but the relative effect on sugar gain was lower. Good quantitative agreement was achieved between the measured and predicted results for sugar gain and water loss for both fresh and frozen mango tissues with a membrane permeability to water of 5.8 x 10(-11) mol s(-1) N-1, a tortuosity factor of 1.0 and a ratio of water to sugar flux across the membrane of 0.35 for fresh and 0.1 for frozen tissue. (C) 2007 Elsevier Ltd. All rights reserved.