Water Activity Testing (Aw) for Food Safety and Shelf Life
Accurate Water Activity Testing for Food Manufacturers, Processors, and Product Developers
Water activity testing, commonly referred to as Aw testing, is an important analytical tool used by food manufacturers, processors, product developers, quality assurance professionals, and regulatory specialists to evaluate the amount of available water in a food product.
Unlike total moisture content, water activity measures the water that is available to support microbial growth and participate in chemical and physical reactions. Understanding a food product's water activity can help manufacturers evaluate microbial stability, shelf life, formulation, packaging, processing controls, and overall product quality.
EMSL Analytical provides professional Water Activity Testing for food and food ingredients to help companies obtain reliable laboratory data for quality control, research and development, product verification, and food safety programs.
What Is Water Activity?
Water activity is expressed as Aw and ranges from 0.00 to 1.00.
Pure water has a water activity of approximately 1.00. As water becomes bound by ingredients such as salt, sugar, proteins, and other components, less water may be available for microorganisms and chemical reactions.
Water activity is different from moisture content.
A product may contain a significant amount of moisture while still having relatively low water activity if much of that moisture is tightly bound within the food matrix.
For this reason, measuring water activity can provide valuable information that moisture percentage alone cannot provide.
Why Is Water Activity Testing Important?
Water activity can influence several important characteristics of food products, including:
Food manufacturers can use water activity laboratory testing as part of product development, quality assurance, hazard evaluation, shelf-life studies, and ongoing production monitoring.
Water Activity and Food Safety
Available moisture is one of the factors that can affect the ability of microorganisms to grow in food.
Foods with higher water activity generally provide conditions that are more favorable for microbial growth, while reducing available water may inhibit the growth of many microorganisms.
The U.S. Food and Drug Administration uses Aw 0.85 as an important regulatory reference point in several food regulations and guidance documents.
However, a water activity result should not be interpreted by itself as proof that a food product is safe. Factors including pH, formulation, processing, temperature, packaging, preservatives, storage conditions, and the microorganisms of concern may also need to be considered.
Laboratory water activity testing provides manufacturers with objective data that can be incorporated into a broader food safety and quality program.
Water Activity Testing for Shelf-Life Studies
One of the most common applications of Aw testing is evaluating product stability and shelf life.
Changes in water activity can contribute to:
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Mold growth
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Yeast growth
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Loss of crispness
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Moisture migration
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Caking or clumping
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Texture changes
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Ingredient degradation
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Reduced product quality
Testing water activity at different stages of a product's shelf life can help manufacturers understand how the product changes during storage.
Aw results may also be evaluated together with microbiological testing, moisture analysis, pH testing, sensory evaluation, packaging studies, and other analytical measurements.
Foods Commonly Tested for Water Activity
Water activity testing may be useful for a wide range of foods and ingredients, including:
Bakery Products
Bread, cakes, cookies, brownies, tortillas, pastries, muffins, crackers, and other baked goods.
Snack Foods
Chips, crackers, pretzels, cereal products, granola, snack bars, and dried snacks.
Confectionery Products
Chocolate, candy, fudge, gummies, caramels, fillings, frostings, and other confectionery products.
Meat Products
Jerky, dried meats, cured meats, sausage products, and other processed meat products.
Dried Foods
Dried fruits, dehydrated vegetables, powders, spices, herbs, powdered ingredients, and freeze-dried products.
Dairy Products
Cheese, powdered dairy ingredients, dairy-based snacks, and specialty dairy products.
Sauces and Condiments
Sauces, syrups, dressings, spreads, marinades, and condiments.
Pet Foods and Treats
Dry pet foods, semi-moist foods, treats, chews, and specialty animal food products.
Dietary and Nutritional Products
Protein powders, nutritional products, powdered supplements, bars, and specialty formulations.
Water Activity Testing for Product Development
Water activity testing can be particularly valuable during new food product development.
Changing a formulation by adjusting sugar, salt, humectants, proteins, fats, or other ingredients may alter the amount of water available within the finished product.
Product developers can use Aw testing to compare formulations and evaluate how formulation changes may influence:
Testing several prototypes can provide useful analytical data before a product enters full-scale production.
Water Activity Testing for Quality Control
Routine water activity testing can also support food manufacturing quality control programs.
Manufacturers may establish internal Aw specifications for particular products and periodically test finished products to verify consistency.
Routine laboratory testing can help identify unexpected changes caused by:
Consistent analytical testing can help companies identify changes before they result in larger product quality problems.
Why Choose EMSL Analytical for Water Activity Testing?
EMSL Analytical provides laboratory testing services to food manufacturers, processors, ingredient suppliers, restaurants, distributors, consultants, product developers, and other food industry professionals.
Our laboratory capabilities include a broad range of food microbiology and food chemistry testing services that can be used individually or as part of comprehensive product testing programs.
Testing services may include:
Combining water activity analysis with other laboratory services can provide food manufacturers with a more complete understanding of product quality and stability.
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