Application of high-power ultrasound for drying vegetables

High power ultrasound represents a means for food dehydration without affecting the main characteristics and quality of the product. The application of ultrasonic energy can be made alone  or in combination with other kind of energies such as hot -air. In this latter case ultrasound helps in  reducing temperature or treatment time. This paper deals with an experimental work in which the results obtained with different kind of  vegetables ( apple, carrots, mushroom, etc.) under the application of ultrasonic vibration at 20 kHz  are presented. Several experimental techniques such us direct contact of the ultrasonic vibration  with the product, standing wave and near-field conditions were tested, together with hot -air at  several temperatures.