Ultrasound Technologies for Food and Bioprocessing

Frontmatter

Chapter 1. The Physical and Chemical Effects of Ultrasound

Abstract

Ultrasound refers to sound waves above the human hearing range. The physical effects of ultrasound include the turbulence associated with cavitational bubble collapse, microjetting, and the streaming movement of cavitational microbubbles to the pressure antinodes of a standing wave field. These physical effects are strongest near to fluid/solid and fluid/fluid boundaries, which mean that ultrasound is extremely effective in enhancing heat and mass transfer within such boundary layers. Chemical effects arise from free radical production during transient cavitational collapse of bubbles.

Sandra Kentish, Muthupandian Ashokkumar

Chapter 2. Acoustic Cavitation

Abstract

The benefit of acoustic cavitation owes to its ability to concentrate acoustic energy in small volumes. This results in temperatures of thousands of kelvin, pressures of GPa, local accelerations 12 orders of magnitude higher than gravity, shockwaves, and photon emission. In a few words, it converts acoustics into extreme physics.

Olivier Louisnard, José González-García

Chapter 3. Ultrasound Applications in Food Processing

Abstract

Food scientists today are focused on the development of not only microbiologically safe products with a long storage life, but, at the same time, products that have fresh-like characteristics and a high quality in taste, flavor, and texture. This focus is based on the needs of the consumer, which is one of the main reasons for constant research in the so-called area of emerging technologies. Traditionally, thermal treatments have been used to produce safe food products. Pasteurization of juice, milk, beer, and wine is a common process in which the final product has a storage life of some weeks (generally under refrigeration). However, vitamins, taste, color, and other sensorial characteristics are decreased with this treatment. High temperature is responsible for these effects and can be observed in the loss of nutritional components and changes in flavor, taste, and texture, often creating the need for additives to improve the product.

Daniela Bermúdez-Aguirre, Tamara Mobbs, Gustavo V. Barbosa-Cánovas

Chapter 4. The Thermodynamic and Kinetic Aspects of Power Ultrasound Processes

Abstract

Most high intensity or power ultrasound applications involve a special transmission mode of sound waves in a medium that is composed of consecutive compressions and rarefactions. Since the propagation of such longitudinal waves is normally associated with a liquid medium, the use of power ultrasound is often termed as sonication. When the negative pressure in the rarefaction phase surpasses the tensile stress of the liquid, the liquid will be torn apart and cavities will be formed (Leighton, 1994). The inception of cavitation and the subsequent mechanical and chemical effects rising from the cavitation activity enable interactions between the acoustic energy and food and biological systems being processed. Such interactions take place at microscopic levels as the average diameters of cavitation bubbles are at 150–170 μm, for bubbles generated in water by 20 kHz ultrasound transducers (Awad, 1996; Vago, 1992).

Hao Feng

Chapter 5. Wideband Multi-Frequency, Multimode, and Modulated (MMM) Ultrasonic Technology

Abstract

Until recently, traditional high-intensity and fixed-frequency ultrasound has been applied in fields such as cleaning, plastic welding, mixing, and homogenization. However, new industrial ultrasound-related applications, such as sonochemistry, extractions, and waste water treatment, among others, are becoming increasingly important, where traditional fixed-frequency ultrasonic systems are showing certain limitations.

Miodrag Prokic

Chapter 6. Application of Hydrodynamic Cavitation for Food and Bioprocessing

Abstract

Hydrodynamic cavitation can be simply generated by the alterations in the flow field in high speed/high pressure devices and also by passage of the liquid through a constriction such as orifice plate, venturi, or throttling valve. Hydrodynamic cavitation results in the formation of local hot spots, release of highly reactive free radicals, and enhanced mass transfer rates due to turbulence generated as a result of liquid circulation currents. These conditions can be suitably applied for intensification of different bioprocessing applications in an energy-efficient manner as compared to conventionally used ultrasound-based reactors. The current chapter aims at highlighting different aspects related to hydrodynamic cavitation, including the theoretical aspects for optimization of operating parameters, reactor designs, and overview of applications relevant to food and bioprocessing. Some case studies highlighting the comparison of hydrodynamic cavitation and acoustic cavitation reactors will also be discussed.

Parag R. Gogate

Chapter 7. Contamination-Free Sonoreactor for the Food Industry

Abstract

A new sonoreactor technology is presented here, which should open vast development possibilities in various fields of chemical, pharmaceutical, and food industries. It should give a decisive impulse to sonochemistry in these various areas. These exclusive systems use high-power converging acoustic waves in a tube to produce a relatively large volume confined acoustic cavitation zone in flowing liquid reagents. It is well known that numerous chemical reactions are strongly accelerated when they take place inside such a zone. The new cylindrical sonoreactors do not contaminate the processed liquids with erosion products as other devices do. The processing conditions can be widely varied with pressure, power, temperature, and flow rate. The processing capacity of the largest models may be up to several tons per hour, using an electric power input of about 50 kW.

Jean-Luc Dion

Chapter 8. Controlled Cavitation for Scale-Free Heating, Gum Hydration and Emulsification in Food and Consumer Products

Abstract

Cavitation is defined as the sudden formation and collapse of bubbles in liquid by means of a mechanical force. As bubbles rapidly form and collapse, pressurized shock waves, localized heating events and tremendous shearing forces occur. As microscopic cavitation bubbles are produced and collapse, shockwaves are given off into the liquid, which can result in heating and/or mixing, similar to ultrasound. These shockwaves can provide breakthrough benefits for the heating of liquids without scale buildup and/or the mixing of liquids with other liquids, gases or solids at the microscopic level to increase the efficiency of the reaction.

Douglas G. Mancosky, Paul Milly

Chapter 9. Ultrasonic Cutting of Foods

Abstract

In the field of food engineering, cutting is usually classified as a mechanical unit operation dealing with size reduction by applying external forces on a bulk product. Ultrasonic cutting is realized by superpositioning the macroscopic feed motion of the cutting device or of the product with a microscopic vibration of the cutting tool. The excited tool interacts with the product and generates a number of effects. Primary energy concentration in the separation zone and the modification of contact friction along the tool flanks arise from the cyclic loading and are responsible for benefits such as reduced cutting force, smooth cut surface, and reduced product deformation. Secondary effects such as absorption and cavitation originate from the propagation of the sound field in the product and are closely related to chemical and physical properties of the material to be cut. This chapter analyzes interactions between food products and ultrasonic cutting tools and relates these interactions with physical and chemical product properties as well as with processing parameters like cutting velocity, ultrasonic amplitude and frequency, and tool design.

Yvonne Schneider, Susann Zahn, Harald Rohm

Chapter 10. Engineering Food Ingredients with High-Intensity Ultrasound

Abstract

The use of ultrasound in the food industry has increased in the last decades. Ultrasound has been used both to analyze food structure and composition at low ultrasonic intensities and high frequencies and to modify ingredients at high ultrasonic intensities and low frequencies. Application of the latter is referred to as high-intensity (power) ultrasonication and is generally carried out at frequencies of =0.1 MHz and ultrasonic intensities of 10–100 W cm⁻². In the food industry, power ultrasonication has proved to be a highly effective food processing and preservation technology, and use of high-intensity ultrasound with or without heat may be used, for example, to denature enzymes, aid in the extraction of valuable compounds from plants and seeds, tenderize meat, and homogenize or disperse two-phase systems such as emulsions or suspensions (Mason et al., 1996).

Jochen Weiss, Kristberg Kristbergsson, Gunnar Thor Kjartansson

Chapter 11. Manothermosonication for Microbial Inactivation

Abstract

Ultrasound is one of the new technologies of microbial inactivation that has been suggested as an alternative to heat treatments. Despite the improvement of current ultrasound generators some data indicate that the germ-killing efficacy of the process is relatively low under atmospheric pressure and room temperature. Therefore most investigators have tried to improve the efficacy of the process, either by increasing cavitation intensity or by designing combined processes to enhance the lethal effect. This chapter reviews the accumulated knowledge in the last 15 years concerning the microbial lethal efficacy of ultrasonic waves under pressure at room temperatures (manosonication, MS) as well as at mild temperatures (manothermosonication, MTS). The chapter focuses on the microbial MS/MTS resistance and inactivation kinetics, on the effect of physical parameters on the lethality of the treatment and on its control. The mechanisms of action and the possibilities to design combined processes are also discussed.

Santiago Condón, Pilar Mañas, Guillermo Cebrián

Chapter 12. Inactivation of Microorganisms

Abstract

Minimal processing techniques for food preservation allow better retention of product flavor, texture, color, and nutrient content than comparable conventional treatments. A wide range of novel alternative physical factors have been intensely investigated in the last two decades. These physical factors can cause inactivation of microorganisms at ambient or sublethal temperatures (e.g., high hydrostatic pressure, pulsed electric fields, ultrasound, pulsed light, and ultraviolet light). These technologies have been reported to reduce microorganism population in foods while avoiding the deleterious effects of severe heating on quality. Among technologies, high-energy ultrasound (i.e., intensities higher than 1 W/cm², frequencies between 18 and 100 kHz) has attracted considerable interest for food preservation applications (Mason et al., 1996; Povey and Mason, 1998).

Stella Maris Alzamora, Sandra N. Guerrero, Marcela Schenk, Silvia Raffellini, Aurelio López-Malo

Chapter 13. Ultrasonic Recovery and Modification of Food Ingredients

Abstract

There are two general classes of effects that sound, and ultrasound in particular, can have on a fluid. First, very significant modifications to the nature of food and food ingredients can be due to the phenomena of bubble acoustics and cavitation. The applied sound oscillates bubbles in the fluid, creating intense forces at microscopic scales thus driving chemical changes. Second, the sound itself can cause the fluid to flow vigorously, both on a large scale and on a microscopic scale; furthermore, the sound can cause particles in the fluid to move relative to the fluid. These streaming phenomena can redistribute materials within food and food ingredients at both microscopic and macroscopic scales.

Kamaljit Vilkhu, Richard Manasseh, Raymond Mawson, Muthupandian Ashokkumar

Chapter 14. Ultrasound in Enzyme Activation and Inactivation

Abstract

As discussed in previous chapters, most effects due to ultrasound arise from cavitation events, in particular, collapsing cavitation bubbles. These collapsing bubbles generate very high localized temperatures and pressure shockwaves along with micro-streaming that is associated with high shear forces. These effects can be used to accelerate the transport of substrates and reaction products to and from enzymes, and to enhance mass transfer in enzyme reactor systems, and thus improve efficiency. However, the high velocity streaming, together with the formation of hydroxy radicals and heat generation during collapsing of bubbles, may also potentially affect the biocatalyst stability, and this can be a limiting factor in combined ultrasound/enzymatic applications. Typically, enzymes can be readily denatured by slight changes in environmental conditions, including temperature, pressure, shear stress, pH and ionic strength.

Raymond Mawson, Mala Gamage, Netsanet Shiferaw Terefe, Kai Knoerzer

Chapter 15. Production of Nanomaterials Using Ultrasonic Cavitation – A Simple, Energy Efficient and Technological Approach

Abstract

Much effort is currently being devoted to the study of nanomaterials including metallic, inorganic, and polymeric material, due to their wide variety of applications. Nanomaterial science is defined as the creation of functional materials through control of matter on the nanometer length scale, which is normally 1–100 nm and which then exploits novel properties such as physical, chemical, biological, optical, or electronical that can be observed at that length scale. In short, nanoparticles have generated a large research effort because of their properties, which differ markedly from those of their bulk counterpart. It is well known that the properties or behavior of materials are size dependent and so with a change in size, totally different behavior of materials may be obtained. Such nanomaterials hold technological potential in various applications, which include magnetic data storage, ferrofluids, medical imaging, drug targeting, and catalysis, and thus their development is essential in this nanotechnological world. In this chapter, a detailed review has been made about the type of nanomaterials as well as the advantages that could be obtained using ultrasonic cavitation.

Sivakumar Manickam, Rohit Kumar Rana

Chapter 16. Power Ultrasound to Process Dairy Products

Abstract

Conventional methods of pasteurizing milk involve the use of heat regardless of treatment (batch, high temperature short time – HTST or ultra high temperature – UHT sterilization), and the quality of the milk is affected because of the use of high temperatures. Consequences of thermal treatment are a decrease in nutritional properties through the destruction of vitamins or denaturation of proteins, and sometimes the flavor of milk is undesirably changed. These changes are produced at the same time that the goal of the pasteurization process is achieved, which is to have a microbiological safe product, free of pathogenic bacteria, and to reduce the load of deteriorative microorganisms and enzymes, resulting in a product with a longer storage life.

Daniela Bermúdez-Aguirre, Gustavo V. Barbosa-Cánovas

Chapter 17. Sonocrystallization and Its Application in Food and Bioprocessing

Abstract

The chapter aims at understanding in detail, the application of ultrasound for intensification of crystallization operation and covers different aspects such as basic mechanism of expected intensification, reactor designs and overview of existing literature related to food and bioprocess industry applications with an objective of presenting optimum guidelines for maximizing the efficacy of using ultrasound. A case study of lactose recovery from whey has also been discussed in details so as to give quantitative information about the effects of ultrasound in different stages of the crystallization operation and guidelines for optimization of different geometric and operating parameters. Overall it appears that use of ultrasound can significantly improve the crystallization operation by significant reduction in the processing time with generation of better quality crystals and also the recent developments in the design of large scale sonochemical reactors have enhanced the possibility of the application in actual commercial practice.

Parag R. Gogate, Aniruddha B. Pandit

Chapter 18. Ultrasound-Assisted Freezing

Abstract

Freezing is a well-known preservation method widely used in the food industry. The advantages of freezing are to a certain degree counterbalanced by the risk of damage caused by the formation and size of ice crystals. Over recent years new approaches have been developed to improve and control the crystallization process, and among these approaches sonocrystallization has proved to be very useful, since it can enhance both the nucleation rate and the crystal growth rate. Although ultrasound has been successfully used for many years in the evaluation of various aspects of foods and in medical applications, the use of power ultrasound to directly improve processes and products is less popular in food manufacturing. Foodstuffs are very complex materials, and research is needed in order to define the specific sound parameters that aid the freezing process and that can later be used for the scale-up and production of commercial frozen food products.

A.E. Delgado, Da-Wen Sun

Chapter 19. Ultrasound-Assisted Hot Air Drying of Foods

Abstract

This chapter deals with the application of power ultrasound, also named high-intensity ultrasound, in the hot air drying of foods. The aim of ultrasound-assisted drying is to overcome some of the limitations of traditional convective drying systems, especially by increasing drying rate without reducing quality attributes. The effects of ultrasound on drying rate are responsible for some of the phenomena produced in the internal and/or external resistance to mass transfer.

Antonio Mulet, Juan Andrés Cárcel, José Vicente García-Pérez, Enrique Riera

Chapter 20. Novel Applications of Power Ultrasonic Spray

Abstract

Atomization is a process where a liquid is dispersed into droplets in a gas. Ultrasonic atomization was discovered in the 1920s (Loomis and Woods, 1927). Since then, atomization has seen diversified applications in devices such as drug nebulizers, room humidifiers, and air refreshers, as well as in industrial processes such as combustion, prilling, and web coating. In contrast to conventional liquid atomizers, ultrasound atomizers generally handle lower flow rates, and atomization of the liquid is achieved not by pressure, but by the vibration of ultrasonic waves (Morgan, 1993). This latter feature decouples the requirement of orifice geometry and pressure from the flow rate, allowing the flow to be controlled independently. Typically, ultrasonic atomizers excel in accurately processing low flow rates and slurry without clogging issues.

Ke-ming Quan

Chapter 21. High-Power Ultrasound in Surface Cleaning and Decontamination

Abstract

High-power ultrasound is being widely utilized for decontamination in different industrial applications. The same technology is also being investigated as an effective tool for cleaning of components in the decontamination of produce. An understanding of the basic technology and how it works in cleaning various industrial parts should help in applying it on a large scale in the food industry. The technology has evolved throughout the past four decades. Different frequencies were developed and are now industrially available. The frequency range is from 20 kHz to 1 MHz. Current sound technology provides a uniform ultrasonic activity throughout the cleaning vessel, which was a major disadvantage in the earlier technology. The two main driving forces that affect cleaning of surfaces are cavitation and acoustic streaming. Both are generated as a result of the direct interaction of high-frequency sound waves with fluids.

Sami B. Awad

Chapter 22. Effect of Power Ultrasound on Food Quality

Abstract

Recent food processing technology innovations have been centered around producing foods with fresh-like attributes through minimal processing or nonthermal processing technologies. Instead of using thermal energy to secure food safety that is often accompanied by quality degradation in processed foods, the newly developed processing modalities utilize other types of physical energy such as high pressure, pulsed electric field or magnetic field, ultraviolet light, or acoustic energy to process foods. An improvement in food quality by the new processing methods has been widely reported. In comparison with its low-energy (high-frequency) counterpart which finds applications in food quality inspection, the use of high-intensity ultrasound, also called power ultrasound, in food processing is a relatively new endeavor. To understand the effect of high-intensity ultrasound treatment on food quality, it is important to understand the interactions between acoustic energy and food ingredients, which is covered in Chapter 10. In this chapter, the focus will be on changes in overall food quality attributes that are caused by ultrasound, such as texture, color, flavor, and nutrients.

Hyoungill Lee, Hao Feng

Chapter 23. Ultrasonic Membrane Processing

Abstract

A membrane is a sermipermeable material that permits the passage of some molecules while retaining others. Ultrasound can enhance membrane operation through the asymmetric collapse of cavitating bubbles and through the turbulence associated with acoustic streaming. The added turbulence can lead to a looser, more porous fouling cake layer and may agglomerate fine particles, reducing pore blockage and cake compaction.These effects are dependent upon the ultrasonic intensity, the operating pressure, crossflow velocity and solids concentration.Membrane cleaning can also be enhanced by the use of ultrasound, but this application may not be economic when used in isolation. One of the greatest challenges facing the technology is the generation of a uniform acoustic field across the entire membrane surface in a full-scale module.

Sandra Kentish, Muthupandian Ashokkumar

Chapter 24. Industrial Applications of High Power Ultrasonics

Abstract

Since the change of the millennium, high-power ultrasound has become an alternative food processing technology applicable to large-scale commercial applications such as emulsification, homogenization, extraction, crystallization, dewatering, low-temperature pasteurization, degassing, defoaming, activation and inactivation of enzymes, particle size reduction, extrusion, and viscosity alteration. This new focus can be attributed to significant improvements in equipment design and efficiency during the late 1990 s. Like most innovative food processing technologies, high-power ultrasonics is not an off-the-shelf technology, and thus requires careful development and scale-up for each and every application. The objective of this chapter is to present examples of ultrasonic applications that have been successful at the commercialization stage, advantages, and limitations, as well as key learnings from scaling up an innovative food technology in general.

Alex Patist, Darren Bates

Chapter 25. Technologies and Applications of Airborne Power Ultrasound in Food Processing

Abstract

Applications of ultrasonic waves are generally divided into two groups: low intensity and high intensity. Low-intensity applications are those wherein the objective is to obtain information about the propagation medium without producing any modification of its state. On the contrary, high-intensity applications are those wherein ultrasonic energy is used to produce permanent changes in the treated medium.

Juan A. Gallego-Juárez, Enrique Riera

Backmatter