In this study, the drying process of pumpkin thin layers was investigated by cast tape drying (CTD) and convective hot air drying (CHD) methods and the effect of temperature and drying kinetics of the pumpkin was determined along with  the best mathematical model to fit the changes on moisture content to time ratio. At first, Pumpkin slices were prepared with 3, 5 and 7 mm thicknesses. Drying was performed at 75, 85 and 95 (°C) by CTD method and at 55, 65 and 75(°C) by CHT method in triplicate. Based on the kinetic model evaluated by Hii, Law and Cloke, the 7 mm thickness was selected as an optimum thickness in both drying methods. The optimal drying temperature ranges were 55 and 95 (°C) by CHD method and CTD method, respectively. Five mathematical kinetic models were fitted on the experimental data using four criteria including, Determination of Coefficient (R²), Root Mean Square Error (RMSE), Sum of Squares (SSE) and Chi-square (χ²). Also, effective diffusion coefficient (D) and activation energy (Ea) were calculated. The results showed that Hii, Law and Cloke’s model predicted the drying behavior during CTD. Activation energy of 37.5310588kJ/mol and 20.32657 kJ/mol was calculated for CHD and CTD methods respectively. The best mathematical model for drying a thin layer of pumpkin by CTD and CHD method was proposed Hii, Law and Cloke’s model.

Keywords: Convective hot air, Pumpkin, Kinetic modeling, Cast tape drying, Thin layer drying

Full-Text [PDF 5633 kb]   (1023 Downloads)