Cherry tomato samples were osmotically dehydrated in different hypertonic NaCl solutions (with or without sucrose) at two different concentrations. Mass transfer kinetics were modelled according to Peleg, Fick and Page equations. The Peleg equation presented the best fitting for water loss and Page model showed the best predictive capacity for salt gain data. The effective diffusivity determined using FickÕs second law applied to a spherical geometry was found to be in the range of 0.43 Â 10 À9-1.77 Â 10 À9 m 2 /s for water loss and 0.04 Â 10 À9-0.54 Â 10 À9 m 2 /s for salt gain. Increased solution concentration resulted in higher water loss and salt gain. An addition of sucrose to osmotic solutions decreased the driving force of the process.

a b s t r a c tThe aim of this work was to study and to model the drying kinetics of fresh and ultrasonic pretreated banana cv Pacovan using the diffusional model (Fick's second law) and an empirical two parameters model (Page model). The pretreatment was carried out in an ultrasonic bath at 30°C. The drying process was carried out in a fixed bed dryer at two different temperatures (50 and 70°C) and 3.0 m/s air velocity. Page empirical model provided the best simulation of the drying curves. The diffusional model was used to describe the moisture transfer and the effective diffusivities of water were determined and were in the order of 10 À9 m 2 /s. These diffusivities increased with increasing temperature and with the application of ultrasound, while the process time reduced, which can represent an economy of energy, since air drying is cost intensive.

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