Evaluation of some thin-layer drying models of persimmon slices (Diospyros kaki L.)

The effect of blanching and drying temperature (50, 60 and 70 degrees C) on drying kinetics and rehydration ratio of persimmons under hot-air drying was investigated. It was observed that both the drying temperature and blanching affected the drying time. The shortest drying times and highest rehydration ratios were obtained from blanched samples. Six thin-layer drying models were evaluated in the kinetics research. The fit quality of the proposed models was evaluated by using the determination of coefficient (R-2), reduced chi-square (chi(2)) and root means square error (RMSE). The Midilli et al.. Page and Weibull models showed a better fit to experimental drying data as compared to other models. Effective moisture diffusivity (D-eff) ranged from 7.05 x 10(-11) to 2.34 x 10(-10) m(2)/s calculated using the Fick's second law. The activation energies of blanched and control samples determined from slope of the Arrhenius plot, In(D-eff) versus 1/(T + 273.15), was 30.64 and 43.26 kJ/mol, respectively. (C) 2011 Elsevier Ltd. All rights reserved.