Ultrasonically assited atmospheric freeze-drying of orange peel: comparison between plate and tubular transducer arrangement

Abstract

Ultrasound application enhance atmospheric freeze-drying. Most studies are performed at laboratory level using cylindrical transducers. However, platetype transducers would allow a easier implementation at industrial scale. Orange peel is the main by-product of the juice industry and the ultrasonically assiste atmospheric freeze-drying could be an interesting alternative to preserve it. The aim of this work was to compare the efficiency of two different ultrasonic transducer, cylindrical and plate, on the atmospheric freeze-drying rate of orange peel. Ultrasound application significantly decreased drying time in every case tested, however, the magnitude depended of the power applied. Thus, the drying rate obtained with a cylindrical transducer at 50 W were in the same range of those of a plate transducer at 150 W. This result is a first steep to scale up the technique..