Selected applications of ultrasonics in food processing

Ultrasonic processing in simple terms is the application of sound waves in the frequency range of 20 kHz-1 MHz which is above the range of human hearing. This review focuses on the applications of ultrasound to accelerate processes such as dehydration, drying, freezing and thawing, tenderization of meat, crystallization of lactose and fat and to improve processes such as cutting, extraction, emulsification, ageing of wines and esterification. The effect of ultrasound on physical properties such as viscosity, opacity, particle size and gel strength is also considered. We find that it is the physical effects of ultrasound that predominate in most applications considered to date. Ultrasound increases heat and mass transfer, disrupts aggregates and can break macromolecular chains.