Effect of drying methods on thin-layer drying characteristics of hull-less seed pumpkin (Cucurbita pepo L.)

An experimental study was performed to determine the drying characteristics of hull-less seed pumpkin using hot air, solar tunnel and open sun drying methods. For the hot air drying, the test samples were dried in a laboratory scale hot air dryer at a constant air velocity of 0.8 m/s and air temperature in the range of 40-60 degrees C. For solar drying experiments, a solar tunnel dryer was constructed at a low cost with locally obtainable materials. The moisture transfer from the test samples was described by applying the Fick's diffusion model and the effective diffusivity was calculated. Temperature dependence of the effective diffusivity was described by the Arrhenius-type relationship. The experimental. drying data of hull-less seed pumpkin were used to fit the Page, Henderson and Pabis, logarithmic and two-term models, and drying rate constants and coefficients of models tested were determined by non-linear regression analysis. Among the various models tested to interpret the drying behaviour of hull-less seed pumpkin, one was selected which presented best statistical indicators. (c) 2006 Elsevier Ltd. All rights reserved.