Mathematical modelling of osmotic dehydration kinetics of apple cubes

Apple cubes were osmotically dehydrated at 25, 40 and 60C, using sucrose or sorbitol, and the mass ratio of sample to solution of 1: 4 and 1: 10, at atmospheric pressure or vacuum pressure of 150 mbar. Six mathematical models were tested to describe the mass transfer kinetics of water loss (WL) and sugar gain (SG). Crank's, Azuara's, Peleg's, Page's and Weibull's models could fit well the experimental data, but the Penetration model resulted in a poor fit. The mass ratio of sample to solution did not have an influence on the mass transfer kinetics at the atmospheric pressure. The increase of temperature and the use of sorbitol as the osmotic agent resulted in an increase of the osmotic process rate at both pressures used. Therefore, sorbitol is a good alternative to sucrose. The vacuum presented a tendency to increase the initial rate of WL.