Water activity of multicomponent mixture of solutes and non-solutes

An equation has been derived to calculate the water activity (Aw) of multicomponent mixtures of solutes and non-solutes. The equation is based on a previous Caurie adsorption equation and it depends on the number of component ingredients and the initial moisture contents of the ingredients in the mixture. Solute and non-solute/water interaction effects in solution were identified as playing important roles in determining accurate equilibrium Aws of the aqueous mixtures. The new equation allows for interaction effects in mixed solution/suspensions and has been tested on model foods (the data was taken from the literature) containing up to five solutes and non-solute components. The equation displays a high degree of accuracy. Unlike the Ross equation, which applies only approximately to mixtures of dilute solutions, the new equation applies to mixtures at all solution concentrations and to wet solids.