Thermodynamic Calculation of Multicomponent Phase Compositions

Abstract

Food industry scientists need to predict multicomponent solid fat compositions because fat solid solutions define food texture and physical properties. Experiments were conducted with two multicomponent fats of known composition to determine solid fraction (via NMR), phase fraction, polymorphic form (via XRD) and thermal melting profile (via DSC). A database including melting temperature and enthalpy was digitized. Wesdorp’s methodology, implemented in MATLAB, was used to estimate the equilibrium mole fractions of each phase. The program estimates melting temperatures and enthalpies absent from the database, and estimates interaction parameters for a 2-suffix Margules model. These parameters were used to find the composition at equilibrium for each phase. The estimated overall melting enthalpy of the mixtures was compared to the value obtained by DSC. The predicted temperature values using Wesdorp’s coefficients were unsatisfactory; hence an alternative approach was developed. The estimated overall melting enthalpies agreed well with the experimental enthalpies.