A new high-intensity ultrasonic technology for food dehydration

At present, there is a growing interest in the field of dehydration for preserving food. Ultrasonic energy represents a means to obtain dehydration without affecting the food. This paper deals with an experimental study about the use of high-intensity ultrasound for vegetable dehydration by using a new power ultrasound generator and a procedure in which ultrasonic vibrations are applied in direct contact with the product and under a certain static pressure. The drying effect of this new process is compared with that obtained from forced-air drying assisted by air-borne ultrasonic radiation and from a conventional hot-air drying. The results show that by using the new technology and procedure it is possible to reduce dramatically the treatment time and it is relatively easy to reach a final moisture content in the samples less than 1%. In addition, the product qualities are well preserved, the sample rehydration is higher than 70% and, because of the high efficiency of the new ultrasonic system employed, the energy consumption is low. As a consequence of the results a new technology for industrial applications is under development.