Krokida et al. (2001) and Fernandez et al.(2005) found that the yellowness increased with progressing drying time and reducing moisture content during convective drying of apple slices. It could be related to the volume shrinkage, causing an increase in the carotenoids concentration through the apple slices and thus shifting the color toward the yellowish region. It is also obvious from Fig. 5that the normalized yellowness was significantly higher fordrying air temperature of 60◦C than the drying air temper-atures of 50 and 70◦C. It might be presumably attributedto the continuous reduction of -carotene at the tempera-ture around 60◦C due to the activation of lipoxygenase andperoxidase enzymes, as previously stated.