Simplified method for the prediction of water activity in binary aqueous solutions

This work describes the application of a simplified method to predict the water activity (aw) of binary aqueous solutions in a range of concentrations relevant to intermediate moisture foods. The water activity as a function of molality for several solutes (electrolytes and non-electrolytes) is described by the equation, aw, = 1 − Km, where K is a constant and m is the molality. Values of K are reported for fifteen non-electrolytes and eight electrolytes. The accuracy of water activity prediction by this method satisfies the actual needs in food research.