EZ-100ST(Water Activity Meter)

Chemicals & Foods Machinery of Food Preservatives

EZ-200(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 *


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)


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.




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