State diagrams of candied orange peel obtained using different hypertonic solutions

State diagrams were established for the candied orange peel obtained by saturation with sucrose or glucose-fructose syrup. Differential scanning calorimetry was used to determine the freezing points and glass transition temperatures in order to generate freezing curve and glass transition curve. Curves were modelled by the Chen and Gordon-Taylor equations. Maximal freeze concentration parameters (Xw', Tm' and Tg') were determined from state diagrams in the 0.185-0.218 kg water/kg sample; −36.9 to −34.8 °C; and - 54.6 to −53.3 °C range. All values depended on the glucose, fructose, sucrose, and maltose content. Orange peel candied with 100% sucrose syrup showed that the glass transition curve can predict sugar crystallization when the product moisture content increases. The dependence between the Tg value and moisture content can be used to control the transformations occurring during storage of products containing amorphous sugars. The glucose-fructose syrup applied during candying prevented sucrose recrystallization.