Sorption Behavior of Mechanically Mixed and Freeze‐Dried NaCl/Casein Mixtures

Adsorption isotherms of mechanically mixed and freeze‐dried mixtures of NaCl/casein at solute percentages of 1, 5, 10, 15, and 20 (wet basis) were obtained over the a_w range 0.23–0.927 at 20°C. Experimental isotherm values were compared to those calculated by a mass balance equation. The mechanically mixed samples sorbed additively as predicted by the mass balance equation below 0.755 a_w, whereas the freeze‐dried mixtures sorbed more water than predicted (positive interaction) below 0.755 a_w, Both types of mixtures sorbed less water than predicted by the mass balance equation (negative interaction) above the saturation a_w of the NaCl, 0.755.