Prediction of the sorptional equilibrium relationship for the drying of foodstuffs

After existing correlations were reviewed to predict the equilibrium of foodstuffs with moist air, it was found that they were not adequate. A new equilibrium expression is presented on the basis of equal chemical potentials in the external and internal phases. The resulting equation can be used over most of the range of moisture contents of sugar based foodstuffs including the high moisture region; it also provides simple analytical expressions for the partial derivatives of moisture content with respect to temperature and to water vapor activity.