that the normalized lightness values had an upward parabolic trend with product moisture content.The color of samples became darker and changed from wan to brown, by rapid evaporation of in tracellular free water in the 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 accelerat-ing the Millard reaction, interaction between reducing sugarsand amino acids, at higher moisture content leading to brownpigment formation (Baini and Langrish, 2009). The productstructural 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 slicesstructural modifications, resulting from the cellular changes,