A STUDY OF THE WATER ACTIVITY LOWERING BEHAVIOR OF POLYETHYLENE GLYCOLS IN THE INTERMEDIATE MOISTURE RANGE

This work reports on the experimental determination of water activity (aw) in aqueous solutions of polyethylene glycol 200, 400, and 600, respectively. The measurements were made in the aw range of most interest to intermediate moisture foods formulation (about 0.80–0.95). The observed behavior was very well fitted by Norrish's (1966) equation and a simple relationship was found between Norrish's correlating constant and molecular weight of polyethylene glycols. It was found that this relationship may be explained through a theoretical analysis of the thermodynamic behavior of macromolecules in solution.