Air-coupled ultrasonic evaluation of food materials

This research was performed with the aim of detecting foreign bodies and additives within food products, and to measure selected acoustic properties, without contact to the sample. This would allow use in manufacturing plants on production lines, where contacting the product for ultrasonic inspection would not be feasible. Images of internal structure are reported. The air-coupled system uses capacitive devices which are able to provide sufficient bandwidth for many measurements, including the detection of foreign bodies in cheese, the detection of deliberate additives to chocolate, the detection of fill level and content of metallic food cans, and measurements of frozen dough products. The approach demonstrates that ultrasound has the potential for application to many industrial food packaging environments where non-metallic objects within food need to be detected.