Advances in Ultrasonic and Megasonic Processing of Foods

This article reviews the latest research in the airborne and aqueous-based applications of ultrasound across the wider range of frequencies in food processing. The effects of ultrasound at low and high frequencies, including stable and unstable sound-induced cavitation, microstreaming, biochemical stress responses and effects achieved through standing waves, are described in terms of food structural changes in dairy, meat and vegetable materials. Advances for recent applications in low- and/or high-frequency ultrasound, including enhanced drying and defoaming with airborne ultrasound, emulsification and homogenisation, green extraction methods and high-frequency ultrasound (megasonics) for non-solvent separation in oil extraction processes and separation or fractionation of milk fat. The manuscript concludes with recommendations for reactor design based on the experience gathered lately in installing transducers in industrial vessels for commercial applications in the oil and dairy industries.