This work aims to show the most recent advances on the use of power ultrasound to improve the convective drying of foodstuff. Drying tests have been performed using airborne ultrasonic radiators working at 22 kHz and power capacities up to 200 W. The ultrasound efficiency for the improvement of the drying rate has been assessed considering the influence of different process variables.
Power ultrasound was able to drastically improve the drying rate, regardless whether the water removal is by evaporation or sublimation, of several fruits and vegetables. Although, process variables seriously influenced on the ultrasonic efficiency, the internal structure resulted crucial in determining the good coupling between the ultrasound waves and the material being dried. In addition, high power ultrasound also brought about the degradation of product structure during the drying process.
