State-of-the-art in the Application of Airborne Power Ultrasonic Technologies in Atmospheric Freeze Drying Processes

Airborne power ultrasound (APU) has a great potential for food industry applications due to its ability to induce the desired physical changes in solid products such as vegetables and fruits. It has been extensively reported that the application of APU accelerates the drying rate without producing a significant impact on the final quality of the product. Currently, it has been shown that the application of APU is more effective at low temperature forced-air drying process, such as Atmospheric Freeze Drying (AFD), than at high temperature convective forced-air drying. In fact, at high temperatures, the kinetic rate is reduced as well as the final product quality. This work focus on the integration and testing of the typology of APU with cylindrical radiator transducer (CRT) to ensure efficient energy transmission, as well as on final product quality and cost reduction. The experimental results achieved confirm that this APU application leads to a significant intensification in the AFD processes.