Kinetics of colour changes in dehydrated carrots

Carotenoid degradation and colour loss in dehydrated blanched and unblanched carrot slices during storage at 27, 37, 47 and 57 °C were investigated. The degradation of β-carotene and colour loss followed a first-order reaction. A significant relationship was found between the colour loss and β-carotene degradation in blanched (r =  0.878–0.971, p < 0.05) and unblanched samples (r = 0.903–0.998, p < 0.05). Degradation of β-carotene had an activation energy of 15.8 ± 0.81 kcal mol−1 and 9.3 ± 2.07 kcal mol−1 for blanched and unblanched carrots, respectively. For blanched samples, the activation energies of colour loss determined on the basis of a and b values were 15.7 ± 2.81 kcal mol−1 and 21.7 ± 4.13 kcal mol−1, while those for unblanched samples determined as 10.5 ± 0.62 kcal mol−1 and 14.7 ± 1.30 kcal mol−1, respectively. Nonenzymatic browning of dehydrated carrots was also investigated and this reaction fitted to zero-order kinetic model. Activation energies of nonenzymatic browning occurred in blanched (25.3 ± 2.30 kcal mol−1) and unblanched (25.9 ± 2.61 kcal mol−1) dehydrated carrots was found similar.