ABSTRACT
The effects of high-power ultrasound waves on the physical, biochemical, and microbial properties of foods have attracted a great deal of interest in recent years. This is because ultrasound can produce a variety of effects depending on the ultrasound wave characteristics and product characteristics. Ultrasound can be used to characterize the products as non-destructive or to produce physical transformations. Ultrasound is important in many situations, including natural systems (e.g. communication between rats at ultrasonic frequencies [1]; echolocation by bats and dolphins; detection of ultrasound signals by fish and moths to avoid predators [2,3]), engineering design to minimize cavitation (e.g. erosion of impellers in pumps [4], non-destructive evaluation of manufactured products [5], enhancing the efficiency of industrial processes [6,7]), detection of underwater vessels and oceanography [8], identifying fish stocks [9], medical imaging [10], surgery [11], and physiotherapy [12]. Many of the techniques used in these situations have parallels in food processing, where ultrasound can either be used to monitor processes while minimizing any effects on product characteristics, or to become directly involved in the process, helping to bring about physical transformations in the product. This chapter will focus on the latter aspect, and will include an overview of the history of ultrasound development, the basic principles underlying the effects of sonication on properties of food systems, and the use of ultrasound in food processing, particularly microbial inactivation, heat and mass transfer, and homogenization.
