Using model food systems to develop mathematical models for construction of state diagrams of fruit products

The parameters of the Gordon-Taylor equation (Tgs, k), the Chen equation (E,B) and the maximally freeze-concentrated phase (Tm', Tg'xs') have been regarded as necessary data for construction of state diagrams of sugar-rich foods. These parameters are significantly influenced by the sugar mass fractions; thus mathematical models for constructing the state diagram parameters based on the type and mass fraction of the main solutes of fruits are required. Experiments using model food systems and validation experiments using fruit juices were designed in this work with the purpose of developing, calibrating and validating the performance of mathematical models. Differential Scanning Calorimetry (DSC) was used to evaluate the thermal transitions of 19 model food systems with well-controlled chemical composition and of 5 fruit juices. Mathematical expressions of Tgs,k,E,B,Tg',Tm',xs' as a function of mass fraction of fructose (XF), glucose (XG), sucrose (XS), pectin (XP) and citric acid (XA) and their interactions were developed. A statistical validation (α = 0.05) showed that solute composition-based mathematical models developed in this study are suitable and accurate for construction of state diagrams of real sugar-rich foods in which only the knowledge of their solid mass fraction is required.