Application of airborne ultrasound to intensify the convective drying of food materials

H.T. Sabarez, K. Knoerzer, J.A. Gallego-Juárez, E. Riera, V. Gaukel, S.M. Beck
Oral Presentation B-5-6, The 20th International Drying Symposium (IDS 2016), Gifu, JAPAM, 7-10 August 2016

The conventional way of drying foods is by forced convection at elevated temperatures. This often requires a very long drying time, is highly energy consuming and detrimental to the product quality. The limitations in convective drying processes may be overcome by combining other innovative technologies. One of such technologies that has been demonstrated in previous studies to intensify the convective drying process is by the combined application of airborne ultrasound. In this work, two ultrasonic designs based on airborne application were investigated to assist in convective drying of food materials. A computer-based ultrasonic drying setup was built to allow continuous recording of the process variables in real time and enabled simulation of dehydration to be accomplished under controlled conditions over a range of drying parameters. This enabled investigations of the impact of airborne ultrasound at various power levels and different levels of drying air conditions (i.e., temperature, relative humidity and velocity). This paper discusses the state-of-the-art of airborne ultrasound as applied for intensification to convective drying of food materials to provide insights of the opportunities and challenges with the application of the technology.