Development of a thermodynamic model of aqueous solution suited for foods and biological media. Part B: Prediction of standard formation properties

Abstract

In food and biological processes, aqueous complexes cover a wide diversity of species and the presence of several phases. The modelling of such processes must take into account these specificities, which require a generalization of the existing thermodynamic models of aqueous solutions. The chemical potential (the molar Gibbs free energy) of a given compound is an important variable to characterize the physical‐chemical properties at equilibrium. Its value depends on two parameters: the Gibbs free energy of formation and the activity coefficient. Both are linked to a chosen reference state. Then, the main thermodynamic modelling task consists in the prediction and/or the collection of formation properties data and in the development of a predictive model of activity coefficients. In this study, a method of prediction of the gas phase formation properties of several organic molecules of interest in foods and biological media using the same input data as those of the COSMO‐RS model (i.e., results of quantum DFT/COSMO calculations) is introduced. This kind of fully predictive approach allows the treatment of conformations. This is its main advantage compared to classical group contribution methods. For fifteen of the studied molecules, the Gibbs free energies of formation predicted at infinite dilution in water are also calculated and compared to experimental data.

Development of a thermodynamic model of aqueous solution suited for foods and biological media. Part A: Prediction of activity coefficients in aqueous mixtures containing electrolytes

“…The first step of such a modelling task is to validate its performance on existing data. That is the main goal of the second part of this paper where a new prediction method of formation properties based on the COSMO‐RS approach is introduced for several organic compounds at infinite dilution in water.…”

“…This paper is devoted to the first modelling task, i.e., the development of a predictive activity coefficient model; the second modelling task, i.e., the prediction of formation properties data, is treated by the same authors elsewhere …”

“…This paper is devoted to the first modelling task, i.e., the development of a predictive activity coefficient model; the second modelling task, i.e., the prediction of formation properties data, is treated by the same authors elsewhere. [9] Lei et al [10] have reviewed several "predictive molecular thermodynamic models" able to predict the activity coefficients g i . They stated that it is necessary to provide molecular structures or physical properties of pure components in the mixture in order to describe the phase equilibria properties.…”