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The β-carotene degradation was investigated in carrot (Daucus carota L. cv Nantes) slices during convective drying at three temperatures (45, 55, and 65°C) at an airflow rate of 0.2 m s-1. Degradation kinetics of β-carotene in carrot slices during convective drying followed a first-order reaction. Drying temperature showed a significant effect on the degradation of β-carotene in carrot slices. The range of the reaction rate constants for β-carotene loses were 0.23 ± 0.08-0.48 ± 0.04 h-1. The activation energy of β-carotene degradation is found 33.33 ± 0.05 kJ mol-1. Half-life time was calculated as 3.02 ± 0.04 h at 45°C, which dropped to 1.43 ± 0.03 h at 65°C.

The effects of different drying temperatures on the drying kinetics of tomato slices were investigated using a cabinet-type dryer. The experimental drying data were fitted best to the to the Page and Modified Page models apart from other theoretical models to predict the drying kinetics. The effective moisture diffusivities varied from 1.015 9 10 -9 to 2.650 9 10 -9 m 2 s -1 over the temperature range studied, and activation energy was 22.981 kJ mol -1 .List of symbols a, b, c, n Constants of models k, k 0 , k 1 Rate constants in models, h -1 MR Moisture ratio D eff Effective diffusivity (m 2 s -1 ) D 0Pre-exponential factor of the Arrhenius equation (m 2 s -1 ) E a Activation energy (kJ mol -1 ) LHalf-thickness of the slab in samples, m M t Moisture content, g water/g dry matter M e Equilibrium moisture content, g water/g dry matter M 0

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