Color change kinetics model of apple slices during hot-air thin drying

This study revealed the color degradation of apple slices in a hot air drying process. The indicators containing brightness values(L*),red and green values(a*),yellow and blue values(b*),total color changes(ΔE),chroma,browning index(BI) had been investigated during the hot air drying process of apple slices at60,70,80,90,100 ℃,respectively. Zero-order and first-order kinetics equation had been applied to fit mathematical model. The results showed that the L* of the apple slices with the extension of the drying time gradually reduced,while a*,b*,ΔE,chroma,BI value was gradually increased,and the reaction rate constants(k) values of these parameters as the color of drying temperature rose showed a certain regularity changes.According to the results compared with regression coefficient R2 fit,zero-order kinetics model could better describe and predict the L*,a*,b*,ΔE change of apple slices in the hot air drying process,while the changes of chroma and BI value were more consistent with first-order kinetics model. This model could be for predicting the color change of apple slices during hot-air thin drying,and providing reference for optimization of drying process.