Water activity is a measure of the availability of the energy of “free” water and must not be mixed up with water content (g water / g substrate). The water activity is indicated with the so-called aW value and ranges between 0 (absolute dryness) and 1 (condensing moisture).  Only this part actively participates in the exchange with the ambient moisture and is of great importance with regard to the microbiological durability or the biological functions of the microorganisms.  The “free” water in products is partly responsible for the growth of undesirable organisms such as bacteria or fungi, which produce “toxin” or other harmful substances and has also a significant influence on the chemical behaviour of food, cosmetic, pharma and other products.

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It depends on what your needs are and whether you need to follow norms and standards in your industry.
Here are a few questions you can ask yourself:

– what type of products do I want to measure?

– in what range of 0.01-1.0aw do I expect the water activity value?

– are volatile substances as f.e. acids or strong aromas in the samples ?

– what are the room conditions where the device will be located ?

– what are my requirements regarding accuracy, norms, standards (e.g. ISO, USP, IQ/OQ etc.) ?

We will be happy to go through these and other questions with you, to find the right device. Get in touch with us!

We use the electrolytic resistance sensor which has been developed by novasina.

You want to know more about diffrent sensor types? Contact us here!

Water activity is measured around the world in many industries from food and pharmaceuticals, to oil and chemicals. The water activity instruments can be used in water activity measurement for process and quality control, on the production line, or for laboratory analysis and product development.