Non-contact ultrasonic quality measurements of food products

摘要

There is growing pressure within the food industry to improve food quality measurements, particularly within packaged food products. This inspection may include looking for physical changes occurring with time, non-uniformity of the product, or the presence of foreign body contamination. The need for reliable inspection is becoming increasingly critical due to the continued automation within the industry and the shift in consumer choice towards more prepared foods. This paper describes the applications of a non-contact ultrasonic inspection system which makes use of polymer-filmed electrostatic transducers and signal processing techniques. The system, which operates in through-transmission mode, was used to detect physiochemical changes and density variations in food. One of the applications was developed to evaluate coagulation processes, which were caused by destabilization in milk-based products. In addition, changes in oil properties due to temperature variation were also measured using the non-contact system. Imaging of foreign bodies in solid food and liquid drink were also performed. Measurement of the solidification process, caused by a change in temperature of a liquid medium, will also be shown. The advantage of the system is that these measurements can be achieved without contact to the test samples. This rapid, noncontact and non-destructive technique has shown itself to be a powerful method for investigating the quality and shelf-life of various types of food products. The method could also be applied to production-line situations.