The ERH of a food product is defined as the relative humidity of the air surrounding the food at which the product neither gains nor loses its natural moisture and is in equilibrium with the environment.
3.1.2 Microorganisms vs. aw value
The definition of moisture conditions in which pathogenic or spoilage microorganisms cannot grow is of paramount importance to food preservation. It is well known that each microorganism has a critical aw below which growth cannot occur. For instance, pathogenic microorganisms cannot grow at aw