Water activity can cause expensive problems for food manufacturers, including rancidity, vitamin loss, and microbial growth. That’s why it’s essential to know your products' water activity throughout the supply chain and during the research and development of new products. The three biggest impacts of water on a food product are microbial growth, chemical degradation, and physical deterioration, including loss of crispness, clumping and caking, and toughness in moist products.

Do you have the means to measure water activity? Here at Nyle Systems, we use the Rotronic Hygrow Palm AW, which is easy to use and costs around $3,300. We use the hand-held meter to measure water activity for samples we test dry for customers and prospects in our product testing laboratory.

Our Rotronic meter has a convenient mobile carrying case. It can store data sets into bins to be downloaded and accessed later. With this meter, our engineers can get accurate sample results in less than 10 minutes.

Water activity predicts stability and safety concerning microbial growth, biochemical and chemical reaction rates, and physical properties. By controlling water activity, you may be able to maintain the food's stability, identify microorganisms that may be potential sources of infection and spoilage, minimize non-enzymatic browning and lipid oxidization reactions, and prolong vitamin and enzyme activity, and optimize physical properties, like texture and moisture migration.

Water activity, not moisture content, determines the lower limit of “available” water for microbial growth. Since bacteria, molds, and yeast require “available” water to support growth, designing a product below a critical water activity level provides an effective way to prevent and control growth.

The U.S. Food and Drug Administration has incorporated water activity into safety regulations. For example, 21 CFR 113 states that thermally processed foods are described as being unsusceptible to bacterial growth if water activity is under 0.85 aw. Measuring water activity (aw) can simplify shelf-life determination. This can help stop product failure, predict and lengthen shelf life, and identify the most cost-effective packaging.