WATER ACTIVITY OF FOOD
The water activity (aw-value) is of central importance for the shelf life of food. The greater the proportion of freely available water is, the lower is the shelf life. Available water is the surface water and that part of the physically bound water, which is released at a energy input (heat). The aw (activity of water) is thus temperature dependent. Higher temperatures lead to a higher proportion of free water and thus reduce the shelf life of the food.