Acoustic drying of onion

Drying processes have long been used as a means of preserving foods and other biological materials. In recent years, the use of drying processes has had great impact on both the production and the processing phases of the agricultural industry. Dehydration of three thickness onion slices using sound waves was evaluated at two frequencies, two sound pressure levels and three temperatures. Compressed air served as the driving force of an aerodynamic siren (sound source) as well as the carrier of the evaporated moisture. Experimental results showed that drying rates are increased by acoustic vibrations and the increase depended on the sound frequency. The loss of pungency in onion (measured as the percent of remnant pyruvic acid) was not significantly different at a confidence level of 95% for all variables studied.