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The use of new or non-conventional technologies widens the food processing innovation possibilities. Among technologies with a potential application, high intensity ultrasonics has emerged. Ultrasound is a mechanical wave that can affect transport phenomena. Accordingly, the effect associated to ultrasonic application will be dependent on the medium where ultrasound is travelling and on the material to be affected. In this work, ultrasonic applications in different media, such as liquid, gas and supercritical fluid, are addressed as innovative alternatives to enhance transport phenomena and highlight the main factors affecting the process. 14 Introduction 15Food processing is in constant evolution in response to different challenges. The changes in 16 consumer tastes and the need to produce safe and high quality foods are responsible for the 17 evolution of the established food processes or the development of the new ones. In this sense, 18the introduction of new technologies could lead to a reduction of the processing time or an 19 improvement in operating conditions. These aspects are closely linked to the search for high 20 quality products that preserve the natural characteristics of foods. Another important aspect that 21 must be taken into account is the reduction of the energy needs of the processes, thereby 22 decreasing both environmental and financial costs. Ultrasound is an example of new technology 23 and its application in food processing could lead to both these areas undergoing an 24 improvement. On the one hand, ultrasound could be applied as a diagnosis technique to control 25 aspects, food product or processes. On the other hand, ultrasound could be used to improve 26 food processes by affecting the kinetics, the yield or the product quality. This work will focus on 27 the latter. 28Acoustic waves are mechanical waves that need a material medium to propagate. Usually, they 33variations is used in diagnosis applications to characterize the medium. In these applications, 34the frequency of the waves is in the range of MHz and the power applied is not higher than 1 35W/cm 2 (Patist and Bates, 2008). When the applied power of ultrasound is higher, the acoustic 36 waves could affect the medium generating interesting effects for industrial applications. This use 37of ultrasonic technology is known as "power ultrasound" or "high intensity ultrasound" and the 38 2 main objective is to induce changes in products or processes. In this case, the frequency is in 39 the range of 20-100 kHz (Mason and Lorimer, 2002). 41The aim of this work was to address different power ultrasound applications in order to highlight factors affecting some innovative approaches to food processing. 42 Effects of ultrasound 43The effects produced by high power ultrasound when travelling across a medium are diverse 44and their relative importance depends on the characteristics of the medium. In general, 45ultrasound produces alternating compression and decompression of the media. In liquids, when 46 ultrasonic power attains a th...

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In this paper, changes in ultrasonic properties during thermoxidation of virgin olive oil were studied. Samples of virgin olive oil were heated over different periods of time from 2 to 16 h at 200 degrees C. Oil degradation was characterized by means of physical and chemical changes, i.e., viscosity, color, polar compounds, polymers, and polar fatty acids. Ultrasonic measurements were carried out while the oil sample was cooled from 35 to 25 degrees C. It was found that velocity and attenuation measurements were related to viscosity measurements through a classical equation for viscous liquids. The ultrasonic measurements were also related to the percentages of polar compounds and polymers, which shows the feasibility of using ultrasonic properties to monitor oil quality. Nevertheless, as long as the ultrasonic measurements are temperature dependent, this variable must be controlled in order to obtain repetitive and reliable measurements.

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