In this study the well known BET (Eq. (1) and GAB (Eq. (2)) equations were applied to fit the experimental data and to deter- mine the monolayer moisture values of the samples which is an important parameter contributing to food deterioration. The BET isotherm equation is the most widely used model and gives a good fit in the aw range from 0.05 to about 0.5 for many foods and has been approved by the Commission on Colloid and surface chemis- try of the IUPAC (International Union of Pure and Applied Chemis- try) GAB has been suggested to be the most versatile sorption model available in the literature and has been adopted by the European Project cost 90 on physical properties of foods. In princi ple, it represents a refined version of BET model. The major advantage of the GAB is that it describes the sorption behavior of nearly all foods from zero to 0.9aw (Rizvi, 2005)