ABSTRACT
Water is an important constituent of all foods. In the middle of the twentieth century, scientists began to discover the existence of a relationship between the water contained in a food and its relative tendency to spoil. They also began to realize that the chemical potential of water is related to its vapor pressure relative to that of pure water was more important. This relative vapor pressure (RVP) is termed as water activity or aw. Scott (1957) clearly stated that the water activity of a medium correlated with the deterioration of food stability due to the growth of microorganisms. Thus, it is possible to develop generalized rules or limits for the stability of foods using water
activity along water content. Since then, the scientific community has explored the great significance of water activity in determining the physical characteristics, processes, shelf life, and sensory properties of foods. Recently, Rahman and Labuza (2007) have presented a detailed review on this aspect of water activity. Details of the various measurement techniques are presented by Labuza et al. (1976), Rizvi (1995), Rahman (1995), and Bell and Labuza (2000).
