Mathematical modelling of drying characteristics of blanched field pumpkin (Cucurbita pepo L) slices.

Abstract

Drying kinetics of blanched field pumpkin slices with slice thickness of 10, 20 and 30 mm were investigated at temperatures of 60; 70; 80⁰C. The velocity of convective cabinet dryer was kept constant at 1.5 ms^-1. Mass transfer during drying of field pumpkin slices was described using Fickian model of diffusion with the drying taking place in the falling rate period. The drying curves obtained were fitted to different semi-theoretical and / or empirical thin layer drying models to determine the best-fit model for dehydration of blanched field pumpkin slices by a non-linear regression analysis. The goodness of fit of each model was evaluated using the coefficient determination (R²), the reduced chi-square (c²) and the root mean square error (RMSE) between the predicted and experimental dimensionless moisture ratios. The effective moisture diffusivity (D_eff) of blanched field pumpkin slices increased from 1.17 E-09 to 6.75E-09 m²s^-1 with increase in drying air temperature and slice thickness. Temperature dependence of effective moisture diffusivity followed Arrhenius relationship and the activation energy of diffusion increased from 24.59 to 26.45 kJ/mol.