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.