What is the Aw value or water activity?

Uitleg over aw waarde

Pedak has over 45 years of knowledge and experience in measuring Aw value (water activity) and we are only too happy to share our knowledge! You can read more about water activity in the following blog.

Aw value (water activity)

Measurement is carried out for the purpose of quality control for:

  • Meat / fish
  • Bread and pastries
  • Cheese / dairy
  • Processed food
  • Chocolate / sweets
  • Pharmaceutical products
  • Cosmetics
  • Pasta / dried products
  • Animal feed
  • Etc.


What does the “water activity” parameter actually mean?

1 Total water/moisture
The moisture content is the total amount of water – including molecular bound water – in a product and is expressed as a percentage of the total weight.

2 Water activity (Aw value)
The relative moisture balance of a product; the “free” water present which allows microorganisms to grow. The measurement taken gives us the “water activity” (Aw value) and ranges from 0.03 – 1.000 Aw.

Water is a basic ingredient in food, pharmaceuticals and cosmetics. Monitoring the Aw value can be crucial for ensuring microbial safety during a product’s shelf life and consumption, or for guaranteeing the production process is optimised.


Why measure water activity?

Water activity (Aw value), pH, temperature and other parameters are directly correlated with the growth of microorganisms, with the Aw value and pH value being the two most important ones. Free water that is available to moulds, yeasts and bacteria is responsible for their growth and even the production of toxins. It can cause chemical / biochemical reactions (e.g. Maillard reactions) that have a negative effect on the following product characteristics:

  • texture, flavour
  • colour
  • flavour
  • nutritional value
  • stability (shelf life)

These are just some of the main reasons why the proper measurement of water activity (Aw value) is so important.

Each year we also share our knowledge at symposia.


Pedak is the exclusive distributor of Aw meters made by the Swiss company Novasina.

Click here to see the range of Novasina Aw meters


Information about water activity


Interesting articles about water activity

Feel free to ask us your question!

Do you have a question or would you like to request a quote? Please contact us by phone or send us an e-mail.

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