Water Activity (aw): Definition, Measurement, and Significance for Food, Pharmaceuticals, and Cosmetics
Water activity (aw) is one of the most important parameters for assessing shelf life, product safety, and microbiological stability in the food, pharmaceutical, and cosmetics industries. Unlike water content alone, water activity describes how much water is actually freely available in a product.
What is water activity (aw)?
Water activity (aw) indicates the extent to which water is bound in a product. It is expressed as a value between 0.000 and 1.000 aw.
- aw = 1.000 corresponds to pure water
- aw = 0.000 means there is no freely available water
The higher the water activity, the greater the risk of:
- microbial growth (bacteria, yeast, mold)
- enzymatic and chemical reactions
- shorter shelf life
Important: Water activity is a much more meaningful indicator than water content.
Why is water activity so important?
Monitoring water activity (aw) is critical to product quality in many industries:
Food Industry
- Preventing Mold and Bacterial Growth
- Controlling Texture and Crispness
- Stability of Dry Goods and Baked Goods
Pharmaceutical Industry
- Stability of Active Ingredients
- Prevention of Chemical Degradation Processes
- Compliance with regulatory requirements (e.g., GMP)
Cosmetics Industry
- Protection against microbial contamination
- Stability of Creams, Lotions, and Gels
Water Activity (aw) vs. Water Content
Water content refers to the total amount of water in a product. Water activity (aw), on the other hand, indicates how much of that water is freely available and influences microorganisms, chemical reactions, and shelf life. For this reason, water activity is often a more meaningful indicator for quality control than water content alone. Two products can have the same water content but, due to different water activities, have completely different shelf lives.
How is water activity measured?
Water activity (aw) is determined using high-precision measuring instruments that measure the equilibrium between the product and the ambient air.
Modern systems make it possible to:
- Quick measurements in the lab and on the production floor
- high reproducibility
- automatic temperature control
- Digital Documentation for Quality Assurance Systems
Water Activity Meters for Laboratory and Production Use
Depending on the application, Novasina offers a variety of measurement systems designed to provide precise, reliable, and standards-compliant water activity measurements in both laboratory and production settings:
LabMaster aw neo
High-end reference instrument from Novasina for maximum accuracy, fully thermostated, and 21 CFR Part 11 compliant.
LabTouch-aw
The Novasina LabTouch-aw enables precise and reliable water activity measurements with simple touchscreen operation. Thanks to its user-friendly design, it is ideal for daily use in the lab and in production.
SAL-F Standards
Novasina’s reference salt standards for extremely rapid calibration and verification of water activity meters. S
Typical Applications of Water Activity Measurement
- Quality Control in Food Production
- Incoming Goods Inspection
- Stability Testing in the Pharmaceutical Industry
- Research and Development
- Production Monitoring (AT-Line / In-Line)
Water activity (aw) is a key quality parameter for safe, stable, and shelf-stable products. It provides crucial information about microbiological risks and product behavior—far beyond traditional moisture content.
Modern water activity meters enable fast, precise, and standard-compliant measurements in both the laboratory and production settings, making them an indispensable tool for quality assurance.
Would you like to reliably determine the water activity in your products or find the right measurement system for your application?
We’d be happy to advise you on selecting water activity meters for laboratory, production, and quality control applications. Whether in the food, pharmaceutical, or cosmetics industries—together, we’ll find the optimal solution for precise, standards-compliant, and reproducible water activity measurements.
Please contact us for a personalized consultation, a product demonstration, or more information about Novasina water activity meters and calibration standards.