It could be interpretedby increasing the rate of browning due to the proceeding of theMaillard reaction at a long drying period. In general, it wouldbe very controversial to conclude that the drying air temper-ature of 60◦C appropriately preserved the samples originalcolor compared to the drying air temperatures of 50 and 70◦Cbased on E. The lowest E for this temperature might be orig-inated from carotenoid decomposition and subsequent colorsshifting in 3D color space during drying. Thus, special cau-tions are obligated in the suggesting an appropriate thermal processing condition for foodstuffs based on color changes.Furthermore, a similar misleading conclusion can be obtained by comparing the E of samples at drying air temperature of 50 and 70◦C due to the color shifting and their interactions. In theother words, the lower E for the samples at drying air temperatures of 50 and 60◦C did not mean that these temperatures were suitable conditions of apple slices drying. Therefore, the foodstuffs quality assessment by monitoring of their appearance heavily relies on the color interactions in 3D color space and all aspects of undergoing process should be considered during analyzing the experimental results.