Mathematical Modeling of Hot-Air Drying of Osmo-dehydrated Nectarines

The influence of osmotic pretreatment on nectarines with solutions of glucose syrup and sorbitol and subsequent dehydration at different temperatures (60 degrees C, 70 degrees C, or 80 degrees C) was evaluated. The kinetics of moisture loss during drying was obtained and mathematical models were adjusted to estimate the kinetic parameters. Effective diffusion coefficients were calculated using Fick's second law. All drying kinetics exhibited only a falling-rate period during hot-air drying owing to moisture loss in the osmotic pretreatment. Moisture loss was favoured by the use of sorbitol, whereas the diffusivity of water increased when glucose was used as an osmotic agent. Logarithmic and Midilli et al. models best described the changes in moisture over time, whereas Fick's second law estimated water diffusion coefficient values between 4.96 x 10(-9) and 2.43 x 10(-8) m(2) s(-1). These models may be employed to predict the optimum conditions for osmo-dehydrating nectarines under hot-air drying at the industrial level.