Moisture Sorption Isotherms of Domestic and Imported Milk Powders and Their Calculated Heat of Sorption

This experiment investigated the moisture sorption isotherms (MSI) of domestic and imported milk powders at 15, 25, and 35 degrees C. The MSI of the milk powders showed sigmoid curves for all samples. Also, equilibrium moisture content (EMC) decreased with increasing temperature, and the monolayer moisture content of the domestic samples was higher than that of the imported samples. So, the heat of sorption was higher at low water activity, indicating that the required sorption energy of the domestic samples was lower than that of the imported samples. Accordingly, this experiment determined the optimal storage conditions for stability as well as the energy required for the drying process of domestic and imported milk powders.