Water Activity Meter

Water activity is closely related to food quality. EZ-100ST is a device that measures this water activity easily and accurately. Please feel free to utilize the high accuracy functions for quality management.

It is possible to measure a wide range highly accurately
Measures Aw 0.10 – 0.98 range at Aw ±0.01 with high accuracy.
It is possible to measure with simple operations.
Set the sample and start the measurements by simply pressing the start button.
Automatic Completion Determination System
When the measurement value stabilizes, the completion is automatically detected and the measurement results are displayed when the buzzer sounds.
Compact design
The body of the measurement device is of compact design. It is light and installation is simple.
It is possible to send measurement instructions from and save on a PC.
In addition to operations on the body of the device, it is possible to send measurement instructions from a PC. Moreover, data can be imported to a PC and it is possible to monitor measurement status and save log data.
* Measurement time 15 minutes on average *

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Product name Water Activity (Aw) Measurement Device
Model EZ-100ST
Sensor electrical resistance type(High polymer)
Measurement range Aw0.10 – 0.98
Measurement accuracy Aw±0.01 (25℃ in incubator)
Internal resolution Aw±0.002
Calibration 4 points (Aw 0.33, 0.53, 0.75, 0.93) 25℃
Usage environment
15℃-35℃(no condensation)

Electricity requirements
AC100v (adapter, DC9V internal (+) type)

Dimensions 165(W)×128(H)×258(D)mm
Weight 3.9Kg
Accessories 1 electrical adapter, 1 PC connection cable, 5 sample containers, Nacl high grade reagent, silica gel, simple user’s manual, CD-R (communication software Awmterm, user’s manual)

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About water activity (Aw)
Ratio of food surface water vapor pressure (P) and pure water vapor pressure (P0).[Water activity Aw = P/P0: numerical value 0 – 1].
When enclosing food in airtight containers, equilibrium relative humidity [E.R.H. % = Aw × 100] in the container.
In addition to water quantity (water content) as a physical property of food, it is used for product design, quality control and HACCP, etc.

The water contained in food is not necessarily always pure water , salts and saccharide in food composition are dissolved into the water, and protein is hydrated. Water activity is a reflection of the status of free water which is water with high fluidity that is not fixed in food and the relationship between the growthof microbes is clear.

<Lowest Water Activity for growth>

Mold: 0.80 (0.65)
Yeast: 0.88 (0.65)
Bacteria: 0.91 (0.75)
*Numerical values in brackets are: halophile, glucose tolerance, xerophilic. There is a trend of higher water activity with the increase in water content but this is not a uniform correlation.