Analytical Methods: Ultrasonic Techniques

Ultrasound may be used to make analytical measurements in solids, liquids, and gases and hence can be used to establish certain physical properties of a number of different dairy products, and to monitor various manufacturing process parameters under a range of environmental conditions such as temperature, pressure, and pH. Ultrasound can be used to determine composition, density, compressibility, temperature, elastic modulus, texture, and microstructure, as well as to locate and characterize voids or inclusions, and monitor aggregation processes. In this article, the underlying theory of the most common ultrasonic measurement techniques is described, and the relationships between typical ultrasonic measurands and physical properties are presented. Practical considerations for ultrasonic tests are discussed, and the operating principles of a selection of specific ultrasonic process monitoring methods including level measurement, flow measurement, and tomographic imaging are outlined.