It is clear from Fig. 5 that the normalized lightness values had an upward parabolic trend with product moisture content.The color of samples became darker and changed from wanto brown, by rapid evaporation of intracellular free water inthe primary stage of drying process down to moisture ratio of0.7, noteworthy due to the non-enzymatic browning reactions(Niamnuy et al., 2007). It could be paraphrased by accelerating the Millard reaction, interaction between reducing sugars and amino acids, at higher moisture content leading to brown pigment formation (Baini and Langrish, 2009). The product structural shrinkage, causing an increase in samples opacity,could be also mentioned as reason for this finding (Contreraset al., 2008). As well, the major proportion of apple slices structural modifications, resulting from the cellular changes