Water Activity
Freely available water in the food
· If salt/sugar is added the water binds tightly to it so the amount of freely available water is reduced, hence the aw is reduced (the addition of salt/sugar increases the osmotic pressure)
Staphylococcus aureus can survive relatively high salt levels
· An alternative way of reducing the aw is to remove the water by dehydration
· Most bacteria require aw >0.95