Megasonic Separation of Food Droplets and Particles: Design Considerations (original) (raw)
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Ultrasonic Mass Transfer Enhancement in Food Processing
Food Preservation Technology, 2002
High intensity ultrasound produces a series of effects on a medium that can influence mass transfer processes. This influence could be linked to effects on external or internal mass transfer resistance. External mass transfer improvement is mainly due to the decrease in the boundary layer thickness. Internal effects could be linked to the changing pressure field within the product caused by ultrasounds. Two methodologies to measure the ultrasound intensity were compared: acoustic pressure and a calorimetric method. Four different types of products were examined in order to illustrate the influence of ultrasound on different mass transfer processes. Acoustically assisted air drying of carrots shows the problem of transmitting ultrasound in gas medium nevertheless it also shows the feasibility of improving food drying. On liquid applications mass transfer is also improved. In porous materials, ultrasound assists the exit of air from the pores which are replaced with the surrounding solution. In products with air filled pores, such as apples, the influence of ultrasound on mass transfer is greater than in materials with liquid filled pores, such as cheese. In some processes, ultrasound influence only appears when a threshold of intensity is exceeded. This is the case of loin brining.
Ultrasound is one of the emerging technologies that were developed to minimize processing, maximize quality and ensure the safety of food products. In recent years, ultrasound technology has been used as an alternative processing option to conventional thermal approaches. Although Ultrasonication methods have been used for years in research and diagnostics, major advances have been made in the last decade. The applications for which high power ultrasound can be used range from existing processes that are enhanced by the retrofitting of high power ultrasonic technology, to the development of processes up to now not possible with conventional energy sources. The present paper reviews the generation, principle mechanism, properties, process parameters, applications, merits and demerits and future trends of the ultrasound technology in the food processing.
Ultrasonic processing and mechanical testing in food technology and biotechnology
2012
Implementation of high intensity ultrasound in food technology and biotechnology (intensities above 1 W/cm, usually in range 10 – 1000 W/cm and frequencies 20 – 100 kHz) become one of the most progressive technologies that are used in many technological processes in food industry. The most represented are drying, mixing, homogenization, extraction, crystallization etc. Stability and physical/chemical properties of food emulsion usually depend on the method to create it. The application of ultrasonic homogenization influenced by high intensities of ultrasonic waves is defined by diameter of the ultrasonic probe and nominal power of ultrasonic processor.
Separation of solid-liquid suspensions with acoustic energy.
A theoretical and experimental study was carried out to investigate the possibility of separating solid-liquid suspensions of water and talcum powder, as well as in a process cooling water system, by means of a standing ultrasonic acoustic wave. Separation was successfully achieved with suspensions of water and talcum powder. The separation of suspended solids from the process cooling water was unsuccessful owing to the extremely small sizes of the suspended solid particles. a_~_ e~ E= F(po/ p,) = f= h= K(k)2/n = k= P= r..~. T= U ~ 2= /t= po pl-= NOMENCLATURE diameter of particles (mm) velocity of sound in water (m/s) energy density of the acoustic field (Nm/m 3) density fi~ctor frequency (Hz) reference position measured from node or antinode (m) amplitude factor 2rt/wavelength (m ~) radiation pressure (N) radius of particles (mm) time per~tod for movement of a particle to a node or antinode(s) particles velocity (m/s) wavelen~;th (mm) viscosity (kg/m.s) density of fluid (kg/m 3) density of particles (kg/m 3~
Ultrasonics in food engineering. Part I: Introduction and experimental methods
Journal of Food Engineering, 1988
The basic ideas underlying the use of ultrasound in non-destructive testing are reviewed with a special emphasis on their relevance to food engineering. Sound velocity is a valuable engineering tool because of its relative ease of measurement, ease of interpretation of the consequent data and its greater accuracy than attenuation measurements. It is a non-destructive, non-invasive, non-intrusive technique. Low-intensity applications are reviewed and their potential in the measurement of physical properties is emphasised. Such measurements include the determination of adiabatic compressibility, rigidity and, in two-phase systems, particle size and dispersed-_vhase volume fraction. Experimental techniques which the authors have found useful for measurements in food systems are described and the accuracy of available techniques is compared.
Applications and potential of ultrasonics in food processing
Trends in Food Science & Technology, 2004
Ultrasound has attracted considerable interest in food science and technology due to its promising effects in food processing and preservation. As one of the advanced food technologies it can be applied to develop gentle but targeted processes to improve the quality and safety of processed foods and offers the potential for improving existing processes as well as for developing new process options. Some applications like cutting or sieving have already found their place as state of the art technologies. Others are currently considered as possible candidates for industrial application. In this review selected and potential applications of ultrasound mainly in the field of food preservation and product modification are discussed. #
Airborne Power Ultrasonic Technologies for Intensification of Food and Environmental Processes
Physics Procedia, 2016
Airborne power ultrasound is a green technology with a great potential for food and environmental applications, among others. This technology aims at producing permanent changes in objects and substances by means of the propagation of high-intensity waves through air and multiphase media. Specifically, the nonlinear effects produced in such media are responsible for the beneficial repercussions of ultrasound in airborne applications. Processing enhancement is achieved through minimizing the impedance mismatch between the ultrasonic radiator source and the medium by the generation of large vibration displacements and the concentration of energy radiation thus overcoming the high acoustic absorption of fluids, and in particular of gases such as air. Within this work the enhancing effects of airborne power ultrasound in various solid/liquid/gas applications including drying of solid and semi-solid substances, and the agglomeration of tiny particles in air cleaning processes are presented. Moreover, the design of new ultrasonic devices capable of generating these effects are described along with practical methods aimed at maintaining a stable performance of the tuned systems at operational powers. Hence, design strategies based on finite element modelling (FEM) and experimental methods consolidated through the years for material and tuned assembly characterizations are highlighted.
High Intensity Ultrasound Processing in Liquid Foods
Food Reviews International, 2020
High-intensity ultrasound assisted food processing is a promising and emerging non-thermal method, having broad applications in various food processing operations such as homogenization, extraction, degassing, de-foaming, emulsification, crystallization, cleaning, etc. The shelf life of the liquid food materials can be augmented by the means of ultrasound due to its antimicrobial and enzyme inactivating property. The loss of volatile components such as aroma and flavorings, pigments, nutrients and vitamins, antioxidants, polyphenols, etc. can be restricted to a large extent by the application of a controlled ultrasound processing. However most of the research on food processing assisted by ultrasonication is reported to be conducted at laboratory scale therefore modelling remains a vital aspect that needs to be further studied for scaling up the process for the commercial purposes.
Separation of solid-liquid suspensions with ultrasonic acoustic energy
Water Research, 1997
A theoretical and experimental study was carried out to investigate the possibility of separating solid-liquid suspensions of water and talcum powder, as well as in a process cooling water system, by means of a standing ultrasonic acoustic wave. Separation was successfully achieved with suspensions of water and talcum powder. The separation of suspended solids from the process cooling water was unsuccessful owing to the extremely small sizes of the suspended solid particles. © 1997 Elsevier Science Ltd