State diagram of deglet nour dates by differential scanning calorimetry

The state diagram of Deglet Nour dates was developed using freezing curve, glass transition line, and maximal-freeze-concentration condition. Freezing points and glass transition temperature of Deglet Nour were measured by differential scanning calorimetry (DSC). The freezing curve and glass transition line were modeled using the Clausius-Clapeyron equation, adjusted with unfreezable water, and the Gordon-Taylor model, respectively. Maximum-freeze-concentrated conditions was found as Xw' (characteristic water content) = 0.22 [Xs' (characteristic solid content) = 0.78] with the characteristic temperature of glass transition being Tg' (characteristic glass transition) = - 48°C and Tm' (characteristic end point of freezing) = - 38.2°C. The developed state diagram can be used in determining the stability of Deglet nour dates during storage as a function of temperature and moisture content. In addition optimum drying and freezing conditions could be identified from the state diagram.