Accurate water activity testing to assess microbial risk, shelf stability, and regulatory status, helping food and agricultural products meet safety standards and maintain consistent quality.
The water activity (aw) of a food is the ratio between the vapor pressure of the food, when in equilibrium with the surrounding air, and the vapor pressure of pure distilled water under identical conditions. For example, a water activity of 0.80 indicates that the vapor pressure is 80 percent of that of pure water.
Water activity increases with temperature and reflects the amount of moisture available for chemical reactions and microbial growth. Moisture condition can be measured as equilibrium relative humidity (ERH), expressed as a percentage, or as water activity (aw), expressed as a decimal.
The Baseline of Truth
The Safety Standard
The Industry Apex
Water activity testing evaluates available moisture in food products, helping identify microbial growth risk, support product stability, manage shelf life expectations, and determine regulatory classification under FDA thresholds used across food safety and quality assurance programs industries.
Identifies moisture levels that support bacteria, yeast, and mold growth.
Helps reduce available moisture to inhibit microbial activity.
Supports consistent quality across the product’s shelf life.
Products at aw ≤ 0.85 may fall outside select FDA regulations.
Most foods naturally have a water activity above 0.95, which supports microbial growth and may require additional regulatory controls. When the water activity of a finished product is reduced to 0.85 or lower, it may not be subject to the requirements outlined in 21 CFR Parts 108, 113, and 114. Measuring and documenting water activity is an important step in supporting regulatory compliance and product classification.
5-8 days for purity/quantity testing. Sterility takes 15 days. Rush options available.
