Discription:

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Water Activity (aW) is a measure of the free water in a sample, and ranges between 0…1.  Pure water would have an aW of 1.0.

 

As water activity measures the ‘free’ or ‘active’ water in a sample it is more relevant to growth of organisms, chemical processes, enzyme activity and physical parameters like size and clumping as these are only effected by the water that can be chemically interacted with.

 

Interestingly Water Activity is related to Moisture Content but it is product and temperature specific.

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