Chapter 10: Ultrasonic Food Processing

Active research into the ultrasonic processing of food began about 30 years ago but it is clear that some work had been done before this e.g. in the 1920's it was suggested that ultrasound could provide an excellent method of mixing and emulsification. Since then applications of ultrasound in food technology have expanded and fall into two broad fields: one in which it is used to change the properties of food in some way (power ultrasound) and the other in which it is used as a measurement technique (diagnostic ultrasound). This article will deal exclusively with the former.

It is the mechanical effects of ultrasound that are of most use in food processing and techniques such as cutting and emulsification are now well established. However with the advances in instrumentation and a greater realisation of the potential for ultrasonic applications the breadth of uses has expanded. Commercial interest has been shown in freezing, because the properties of the thawed product are much improved; in sterilisation where ultrasound affords both reduced times and lower temperatures and in processes such as marination and extraction which rely on the liquid penetration into a material.

In these days, when minimal and green processing is a driver for food preparation, power ultrasound can provide useful possibilities for the food technologist. It has several positive aspects which can provide a range of applications in processing but perhaps most significantly it can provide concurrent combinations that include mixing with sterilization, controlled crystallisation with improved heat transfer and many more.