Measurement and Modeling of Lactose Solubility in Aqueous Electrolyte Solutions

Lactose solubility has a significant influence on lactose crystallization. Changes in lactose solubility have an immediate impact on saturation concentration and hence supersaturation, which is used to control the crystallization process. The possibility to model and predict changes in solubility, which are caused by electrolytes, provides a chance to optimize the crystallization processes accordingly. This study explores the influence of different whey salts and salt mixtures on lactose solubility in aqueous solutions. Temperatures from 20 to 50 °C in combination with different salt concentrations are studied. Furthermore, a semipredictive modeling approach using the ePC-SAFT model is presented based on the experimental results. This approach requires pure-component parameters for lactose, dissociated ions, and water, as well as binary interaction parameters for lactose-water, water-ion, and lactose-ion, the latter of which were fitted to lactose solubility data in ternary water-lactose-salt solutions. These parameters have then been applied to successfully predict lactose solubility in multicomponent salt solutions. Until now, a modeling approach for the systems under investigation has not existed in the literature.