Modelling of heat and mass transfer during (osmo) dehydrofreezing of fruits

Simulation of dehydrofreezing process is a difficult task as two processes are involved: a mass transfer of soluble solids and water between the product and the osmotic solution and heat transfer during freezing. A model developed in a prior work for the dehydrating step, was linked with the heat transfer process involved during the freezing step. In this case, the heat transfer process was modelled using the enthalpy formulation with a finite volume scheme. The results of the model were successfully confronted with experimental data obtained on pear disks and apples cubes dehydrated using two osmotic syrups (sucrose and glucose solutions) and followed by freezing in a conventional air-blast tunnel (air at −40 °C). A good quantitative agreement was obtained between the experimental and calculated results for the whole dehydrofreezing process, that is, the dehydration followed by freezing.