Consideration must be given this chart for all areas of product development. What is good for prevention of bacterial groewth may be the worst condition for non-enzymatic browning. Therefore, the product developer needs to do a balancing act and a realistic risk asssessment. It may become necessary to add an inhibitor of some kind in order to yield the correct product image. The amount of water in a product is not as important to its shelf life as is its water activity.
Microbes feed on the free water.
Microbes cannot readily access the interdependent or bound water because they would have to compete with chemical structures within the food itself. A portion of water in food is strongly bound to chemical sites in the food. For example, ydroxyl groups of polysaccharides, the carbonyl and amino groups of proteins and other polar sites that may hold water by hydrogen bonding, ion-dipole bonds or other chemical bonds. Weaker, but not less important bonds are those that solutes present in the food have for water. How strongly the water is bound is expressed in the equilibrium water vapor pressure.