Price of the test:
$46 per analysis
Acceptable Matrices:
Nearly all foods and food products
Unacceptable Matrices:
Samples containing high levels of propylene glycol
Limit of Detection:
0.250 aw units (lower limit)
Sample Size Requirements:
10 grams
Equipment:
Water Activity Meter
Reportable Units:
aw Units
(Water activity, aw is the ratio of vapor pressure of the water in the sample to the vapor pressure of pure water at the same temperature)
Turn Around Time:
7-9 business days
Is Rush Available?
Yes
Method Reference:
AOAC 978.18
Method Description:
This method is a measurement relating to the free, unbound water present in food and food products.
The atmosphere of a special sampling cell is evacuated, repressurized and then measured manometrically. The results are correlated to water activity in the sample
Additional Information:
Water activity has little, if any, relationship to the total moisture content of the food. Water activity does provide a means of assessing the storability and bacterial susceptibility of shelf-stable foods. It is known that microorganisms cannot survive below certain aw levels, the level being dependent upon the type of microorganism: Botuli at <0.93; Bacteria at <0.86; Yeast cells at <0.78 and Mold spores at <0.65.