water activity meterIt is a device used to measure the water activity in samples such as food and medicine, and its value directly affects the shelf life and microbial growth control of the product.
Application Scenario:
Food industry: Control the water activity of pastries, sausages, etc. to extend their shelf life.
Pharmaceutical industry: Ensure drug stability.
Other fields such as cosmetics and aquatic products can also be tested.
Operation process:
Sample preparation: Process samples (such as drugs, sausages, pastries, etc.) into small particles or uniform states.
Measurement steps:
Place the sample into the measurement chamber, select the sample name and testing mode (automatic/timed).
After startup, the instrument automatically displays the water activity value and temperature curve. The testing time varies depending on the sample (such as about 706 seconds for sausages and 987 seconds for mung bean cakes).
Calibration: Monthly calibration with sodium chloride (water activity<0.5) or magnesium chloride (water activity>0.5) solution is required.
The calibration of the water activity meter must meet the following conditions:
Environmental requirements: The temperature should be stable at 25 ± 5 ℃, the humidity should be ≤ 85%, and vibration and electromagnetic interference should be avoided.
Calibration frequency: once a month. If there are large environmental fluctuations or frequent use (such as daily testing), the cycle needs to be shortened.
Judgment criteria:
Data drift (such as three consecutive measurement deviations exceeding ± 0.05);
When the ambient temperature and humidity exceed the above range, recalibration is required.
The calibration method can refer to using saturated solutions such as lithium bromide as standard substances.