Laser-Based Measurements Of Water Activity In Solid Dosage Applications

By D.I. Duncan and J.R. Veale

Water activity a_w, or the relative humidity inside a package, is commonly measured by manufacturers in industries such as food and pharmaceuticals. The food industry has used water activity testing for more than two decades in development and quality control applications. The FDA and USDA consider water activity a key parameter to control mold, fungus and bacterial growth on packaged foods. Food producers also use water activity measurements in product development to understand how water migrates between the package and the product itself, and between the individual food components.