The Wilson et al. model

A large number of food media contain a lipid phase and an aqueous phase in which microorganisms can grow. This situation occurs frequently in food systems such as sauces, for which weak acids are used to ensure food safety. A modified form of the Henderson-Hasselbalch equation has been developed taking into account the partitioning of the undissociated form of the acid in an oil phase, in order to calculate the proportion of weak acid present in its undissociated form in the aqueous phase. 

However, to operate this model requires knowledge of the pKa. Nonetheless, many dissociation constants remain immeasured (for example, for more than half of the dipeptides) as well as the equilibrium constants between two phases. 

From thermodynamic state quantities to the physical-chemicai properties of food 

Due to the limits of the above-mentioned approaches, it is interesting to address the problem of prediction of physical-chemical properties from a different angle. The proposed approach is based on thermodynamics. A methodology has been developed from the exact definition of the physical-chemical properties. This methodology allows us to overcome much of the previous limits. 

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