The Use of Ultrasound for Drying, Degassing and Defoaming of Foods

In this chapter, some important applications of power ultrasound on food processing treatments such as defoaming, degassing and drying have been reviewed and discussed. Firstly, after an initial exposition on fundamentals of ultrasound and main mechanisms involved and devices, the review includes a section on defoaming and degassing of liquids showing the main relevant factors and uses in the fermentation industry. Special attention has been paid on the main advantages of airborne ultrasonic defoaming as compared to other methods. Secondly, it has also been addressed the benefits of ultrasonic intensification of the drying process of solid foods considering the kinetic aspects. The principles, modelling and applications are discussed, taking into account the limitations of the technique and possible improvements to accomplish further developments. Thirdly, the impact on the quality of the product during the assistance of ultrasound in food drying is also judged and described through studies about microbiological, physical, structural and chemical modifications.