Water in dairy products

Abstract

During the last 50 years, our knowledge of the properties and roles of water in foods has progressed very significantly; at the beginning of this period, the emphasis was on the binding of water to other constituents, which was supposed to impart to it special properties, different from those of bulk water. These concepts of free and bound water were used widely, although most often poorly defined. They can now be supplemented by much more precise descriptions of the properties of water present in food products, in terms of thermodynamics and molecular mobility. The concept of bound water in foods (as well as in biological systems) originated in various observations, such as increasing difficulty to dehydrate the materials and increasing irreversibility of the dehydration. The concept was backed up by the knowledge of the unique properties of the water molecule. The dipolar structure of the molecule and its ability to interact with various chemical groups of the other constituents actually are at the basis of the most important role of water in some sensory properties of foods and in many of the changes that occur during processing and storage. © 2009 Springer Science+Business Media, LLC.