Drying kinetics, rehydration and colour characteristics of convective hot-air drying of carrot slices

Abstract

The effects of air drying temperature, slice thickness and pre-treatment application on the drying kinetics of carrot slices during convective drying in the range 50-70 A degrees C were investigated. Results indicated that drying time, rehydration ratio and colour characteristics of carrot slices were more affected by drying air temperature, followed by pre-treatment applications. Five thin-layer drying models were applied to describe the drying kinetics. Midilli et al. model was the best model to characterize the drying kinetics of carrot slices. The moisture effective diffusivity calculated from the second Fick's law of diffusion ranged from 3.46 x 10(-10) to 1.02 x 10(-9) m(2)/s. The values of activation energy determined from the slope of the Arrhenius plot, ln(D (eff) ) versus 1/(T + 273.15), were 35.53, 43.42, and 37.75 kJ/mol for blanch, potas and control samples, respectively.