Did you know that water activity is not the same thing as moisture content? According to the UC-Davis Dairy Research and Information Center: "Although moist foods are likely to have greater water activity than are dry foods, this is not always so; in fact a variety of foods may have exactly the same moisture content and yet have quite different water activities."
This level of activity can have a significant impact on your product as: "Water in food which is not bound to food molecules can support the growth of bacteria, yeasts and molds (fungi). The term water activity (aw) refers to this unbound water."
A common application of water activity measurement is the predicting of product shelf-life and stability especially in foods not relying on refrigerated storage. And for product that will ultimately be refrigerated, water activity measurement can be useful in production processes.
Monitoring and control of water activity in combination with pH and salt can effectively increase product safety and stability. With this in mind, if your lab does not currently test for water activity it may be helpful to add this useful tool to your SOP. To learn more about water activity click here for the full piece from UC-Davis or here for further information from Clemson University. Also, be sure to check out our water activity offerings from Nelson-Jameson by clicking here.
