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Applications of Ultrasonic Cutting in Food Processing
Journal of Food Processing and Preservation
Abstract
With regard to cutting materials, such as bread, rye bread and cake, a lot of methods can be applied. This paper studies the method of ultrasonic cutting in food processing. There are four major components in the typical ultrasonic food cutting system. They are the power supply, the transducer, the booster and the cutting tool. We not only focus on cutting in food processing through comparing the principle of ultrasonic cutting with conventional cutting, but also address practical applications of ultrasonic cutting in food processing through the performance of ultrasonic cutting of bread, rye bread and cake. The results show that ultrasonic cutting can be applied to cut thin slice of food, which the conventional cutting cannot do. Moreover, in order to extend practical applications of ultrasonic cutting in food processing, a novel kinematic mechanism is proposed to satisfy motions of ultrasonic cutting equipment.Practical ApplicationsTo evaluate ultrasonic cutting of foods, on the one hand, we have compared the principles of two methods, which are ultrasonic cutting of foods and conventional cutting of foods; on the other hand, we have investigated the performance of ultrasonic cutting of different materials, such as bread, rye bread and cake. The Results and Discussion section shows that ultrasonic cutting in the industry has not only general benefits and advantages, such as excellent cut surface, reduced crumbling, squeezing, debris and smearing, but also a special advantage, such as cutting thin slice, which cannot be realized by conventional cutting of foods. To extend applications of ultrasonic cutting in food processing, we have designed a novel kinematic mechanism of ultrasonic cutting equipment to demonstrate applications of ultrasonic cutting with intermittent motion.
... Because of the increasing demand for an improved quality of food-cutting processes with high accuracy, excellent cut faces, reduced smearing, low product loss, less deformation, less tendency to shatter for brittle products, and the ability to handle sticky or brittle foods, ultrasonic cutting is becoming increasingly important [6,42]. Ultrasonic cutting is the size-reduction operation that utilizes the vibrating energy of the ultrasound, which superposes with the conventional blade movement, to improve the cutting efficiency and quality of the product [43]. ...
... Ultrasonic cutting is the size-reduction operation that utilizes the vibrating energy of the ultrasound, which superposes with the conventional blade movement, to improve the cutting efficiency and quality of the product [43]. An ultrasonic cutting machine is composed of an ultrasonic transducer, a power supply unit, a horn, and a cutting knife, as shown in Figure 2. In the ultrasonic cutting mechanism, due to the high-frequency vibrations of the cutting blades, the food and cutter experience alternative contact and separation at a high deformation rate, though smaller deformations result in a reduced total cutting force and an avoidance of transversal cracks and crumbling, with a reduction of cutting-surface roughness [42]. The piezo-electric transducer converts the voltage that is supplied by a generator into a corresponding mechanical displacement at the outlet of the piezo element. ...
... The cutting mechanism is more effectively used for cutting viscoelastic and viscoplastic foods, fragile and frozen foods, as well as heterogeneous products. The quality of food cut by ultrasonics, and the cutting efficiency, depends on the geometry of the cutter, the direction of the vibration of the cutter relative to the cutting direction, the frequency and amplitude of the cutter, and the product's properties, such as its microstructure, moisture or fat content, or temperature sensitivity [6,42,44]. ...
The use of non-thermal processing technologies has grown in response to an ever-increasing demand for high-quality, convenient meals with natural taste and flavour that are free of chemical additions and preservatives. Food processing plays a crucial role in addressing food security issues by reducing loss and controlling spoilage. Among the several non-thermal processing methods , ultrasound technology has shown to be very beneficial. Ultrasound processing, whether used alone or in combination with other methods, improves food quality significantly and is thus considered beneficial. Cutting, freezing, drying, homogenization, foaming and defoaming, filtration, emulsification, and extraction are just a few of the applications for ultrasound in the food business. Ultrasounds can be used to destroy germs and inactivate enzymes without affecting the quality of the food. As a result, ultrasonography is being hailed as a game-changing processing technique for reducing organoleptic and nutritional waste. This review intends to investigate the underlying principles of ultrasonic generation and to improve understanding of their applications in food processing to make ultrasonic generation a safe, viable, and innovative food processing technology, as well as investigate the technology's benefits and downsides. The breadth of ultrasound's application in the industry has also been examined. This will also help researchers and the food sector develop more efficient strategies for frequency-controlled power ultrasound in food processing applications .
... The advantages of ultrasound cutting applied to muscle foods are reflected in the flat cutting surface, reduced wastage, and stable shape (less deformable) of the cut product. The ultrasound cutting technology is capable of handling fragile muscle foods, such as minced products, while maintaining an excellent level of hygiene (Liu, Jia, Xu, and Li 2015). The ultrasound cutting characteristics also depend upon the processing condition, e.g. ...
Traditional processing methods can no longer meet the demands of consumers for high-quality muscle food. As a green and non-thermal processing technology, ultrasound has the advantage of improving processing efficiency and reducing processing costs. Of these, the positive effect of power ultrasound in the processing of muscle foods is noticeable. Based on the action mechanism of ultrasound, the factors affecting the action of ultrasound are analyzed. On this basis, the effect of ultrasound technology on muscle food quality and its action mechanism and application status in processing operations (freezing-thawing, tenderization, marination, sterilization, drying, and extraction) is discussed. The transient and steady-state effects, mechanical effects, thermal effects, and chemical effects can have an impact on processing operations through complex correlations, such as improving the efficiency of mass and heat transfer. Ultrasound technology has been proven to be valuable in muscle food processing, but inappropriate ultrasound treatment can also have adverse effects on muscle foods. In the future, kinetic models are expected to be an effective tool for investigating the application effects of ultrasound in food processing. Additionally, the combination with other processing technologies can facilitate their intensive application on an industrial level to overcome the disadvantages of using ultrasound technology alone.
... Ultrasonic cutting assembly for slicing bread. Source: Adapted fromLiu et al. (2015) ...
Ready-to-eat (RTE) and packaged foods have gained popularity and have become an integral part of our daily life. The quality of RTE and packaged foods need to be maintained carefully to avoid any chance of foodborne illness. The probability of foodborne illness can be lowered by careful and real-time surveillance of quality during the supply chain. There are various technologies available such as active packaging, intelligent packaging, etc. which inform the customers about food quality. The technological advancement in the field of nanotechnology such as nanosensors and biosensors has permitted their use in determining food quality. Nanosensor systems such as indicator sensors, time-temperature, and oxygen indicators help to monitor the freshness and quality of food products. Such sensing technologies usually work by focusing on gas production, temperature, and microbial growth within the food package. To monitor the changes, sensors are incorporated inside the food package. All these kind of packaging not only enhances the shelf life but also helps to keep the food clean and protected from the external environment. Nanosensors help for detecting toxins, vitamins, fertilizers, dyes, smell, and even taste. In this chapter, various techniques which are having a great future for ensuring the quality, safety, and well-being of food after packaging are discussed. The technologies reviewed in this chapter have a great budding future in the food packaging field which helps in the real-time monitoring of food.
... HIU has also been used in slicing cheeses, which has gained interest amongst researchers, offering advantages such as accuracy, shorter cutting time, and minimum product loss (Liu, Jia, Xu, & Li, 2015). Most importantly, ultrasonic cutting helps minimize food processing equipment-based cross-contamination (Chávez-Martínez et al., 2020). ...
Background
Cheese preservation has become a major issue for the global cheese industry due to microbial spoilage and the effects of chemical preservatives on human health. Consumer health and environmental awareness have motivated researchers to introduce cheese products that contemplate safety, minimal processing, eco-labels, and clean labels.
Scope and approaches
Preservation strategies include a) advanced technologies comprising non-thermal processing (high pressure, cold plasma, pulsed light, ultrasound) and packaging technologies (bioactive films, coating, and modified atmospheric packaging), b) direct incorporation of natural antimicrobial agents, such as mycocins, endolysins, lactic acid bacteria and their bacteriocins and c) application of various plant extracts, essential oils and propolis.
Key findings and conclusion
Advanced technologies have shown broad-spectrum antimicrobial action with a minimal adverse effect on cheese quality. Methods such as the direct addition of plant extracts negatively affect cheese texture, sensory and physicochemical properties. However, encapsulated and film forms are known to minimize these drawbacks. This review comprehends the sustainable cheese preservation strategies, their effectiveness in shelf-life extension, and physiochemical and quality attributes of cheese post-preservation. Overall, this review can benefit the cheese industry by enhancing market value, consumer satisfaction, and environmental well-being.
... Such arrangements give less crumbling, squeezing, debris and smearing. The aim is to obtain perfect thin slices, better than those produced by conventional cutters in line cutting of bread, dough or cakes (Liu et al. 2015). ...
... The quality of the food cutting by an US cutter is affected by the geometry of the blade, the direction of vibration of the knife relative to the movement of the food, and the frequency and amplitude of the US (Arnold, Zahn, Legler, & Rohm, 2011). US cutting can be applied to cut thin slices of food, which conventional cutting cannot do (Liu, Jia, Xu, & Li, 2015). ...
... Although cutting (shearing) has several engineering applications (Atkins, 2009), food engineers have been more concerned with size reduction of dry solids (milling) than of fresh high-moisture material (Barbosa-Cánovas et al., 2006). Water jets, lasers, and ultrasonic cutters are potential alternatives for precise sizing and cutting operations in culinary practice (Becker & Gray, 1992;Liu, Jia, Xu, & Li, 2015;Mizrahi et al., 2016). ...
Modern consumers are increasingly eating meals away from home and are concerned about food quality, taste, and health aspects. Food engineering (FE) has traditionally been associated with the industrial processing of foods; however, most underlying phenomena related to FE also take place in the kitchen during meal preparation. Although chemists have positively interacted with acclaimed chefs and physicists have used foods as materials to demonstrate some of their theories, this has not been always the case with food engineers. This review addresses areas that may broaden the vision of FE by interfacing with cooking and gastronomy. Examples are presented where food materials science may shed light on otherwise empirical gastronomic formulations and cooking techniques. A review of contributions in modeling of food processing reveals that they can also be adapted to events going on in pots and ovens, and that results can be made available in simple terms to cooks. Industrial technologies, traditional and emerging, may be adapted to expand the collection of culinary transformations, while novel equipment, digital technologies, and laboratory instruments are equipping the 21st‐century kitchens. FE should become a part of food innovation and entrepreneurship now being led by chefs. Finally, it is suggested that food engineers become integrated into gastronomy's concerns about safety, sustainability, nutrition, and a better food use.
... Zahn et al. (2005) reported a better cutting surface appearance and less damage on product structures for yeast dumplings, hamburger buns, and whole-grain bread after UAC. UAC was also reported to reduce deformation, crumbling, and squeezing for porous foods (malted bread, cake) and get a clean cut of multiple-layer bakery products (puddingfilled cake) (Schneider et al., 2011;Liu, Jia, Xu, & Li, 2014). ...
This study was conducted to investigate the effects of ultrasound-assisted cutting (UAC) on surface topography and quality of selected cheese products (cheddar, mozzarella, and Swiss). All cheese samples were cut without (control) and with ultrasound at three amplitudes (30%, 40%, and 50%) with an ultrasonic knife. Quality attributes such as color, pH, peroxide values, surface topography, and sensory characteristics (color, taste, odor, off-flavor, and overall acceptability) of the cheeses were compared. With the set up used in this study, all cheeses cut with UAC exhibited a relatively shining and smooth surface appearance compared with the relatively dull and rough surfaces of the samples cut without ultrasound (control). A better quality was observed when the ultrasound amplitude was increased from 30% to 50%. The cheeses cut with ultrasound exhibited lower peroxide values compared to the control indicating less lipid degradation. UAC showed promise for cutting of foods with improved quality and thus will benefit consumers and the food industry. Industrial relevance Ultrasound-assisted cutting (UAC) has a potential to replace traditional cutting methods due to advantages such as high accuracy, low product lost, less deformation, reduced friction, less down time, and being able to handle sticky or brittle foods, among others. This study provided evidence that UAC improved product quality immediately after cutting and during storage. This will help decision makers in the food industry to apply UAC in their production lines to improve product quality.
Abstract
The need for high-quality and safe food has been steadily increasing. Whereas, the food processing sector is looking for new cost-effective, quick, and more efficient technologies than existing processes. With its vast application in numerous processes, ultrasonic technology has transformed the food processing industry, acting as a sustainable as well as low alternative. This nondestructive technology has various benefits, including faster procedures, increased process efficiency, reduction of process stages, higher product quality as well as retention of product attributes (nutrition value, texture, organoleptic features), and longer shelf life. Electromagnetic waves, on the other hand, are now often used for food processing in commercial, and industrial microwave ovens. Microwaves induce molecular mobility by causing ionic particles to migrate or dipolar particles to rotate. When considering the possible applications of microwave technology in the food sector, it is clear that microwaves offer numerous benefits, including time savings, improved final product quality (taste, color, and nutritional content), and rapid heat generation. However, microwave treatment for food processing with advanced technology has a favorable effect on energy, time, and nutritional value. Ultrasound and microwave (US-MW) are new technologies utilized to improve heat and mass transmission since they are inexpensive, simple, and energy-efficient. The current review focuses on the effects of ultrasonic and microwave processing on the textural, and nutritional aspects of food products and how process variables influence these properties.
Fermentation and emulsification are some of the basic techniques that are used to preserve the quality of food, prolong shelf life and provide special taste and texture. There are different technologies that assist them during the process. Ultrasound and microwave are two modern technologies that are used in many food processing techniques; also have their individual effects on fermentation and emulsification. However, these days microwave-ultrasound-assisted (hybrid processing) processing techniques are used in order to cover the defects possessed by each other. This synergic microwave-ultrasound technology has been studied widely these days. As both of these technologies are less expensive and more effective and valuable. This combination ranges from simple to flow system modification, safe and possible to use. As compared to the individual effect of ultrasound and microwave technologies; microwave-assisted ultrasound synergistically Promotes the peptide content, phenolic compound, and preserves bioactive properties of the products during fermentation and while improving the overall process efficiency it also enhances extraction, antioxidant and emulsification properties. microwave-assisted ultrasound intensifies the process and completes it in a short time with more accuracy. In this chapter, a brief review throws light on the individual and in recent developments combine effects of MW and US on fermentation and emulsification process.
The use of ultrasound in food extraction and processing has been well documented in the literature and there are a number of examples of industrial applications. Nevertheless, the lack of reliable equipment for multi-ton scale production has limited the exploitation of cavitation technologies in the food industry for many years. The technological advances achieved over the last decade, including powerful new units for continuous-flow sonication, have driven the successful transfer of ultrasound technology to industrial applications. The availability of equipment that satisfies the needs of the food industry will further increase the use of this unique non-thermal technology, which can preserve the taste, color and nutritional value of treated foods and beverages. This chapter summarizes the current state of the art and describes all of the main applications of ultrasound in the food industry together with its evident advantages.
Size reduction of solid foods and emulsification or homogenisation of liquid foods are used to change their organoleptic characteristics and their suitability for further processing. This chapter describes the theory of size reduction, the equipment used for milling, slicing, dicing, pulping and homogenisation, and the effects of processing on foods and microorganisms.
Cutting is an imperative operation in the food‐manufacturing factory, separating food into a predefined geometry. A broad range of solid foods, with various components, textures, and structures, pose enormous challenges to conventional cutting strategies. Additionally, the cutting performance is significantly impacted by the processing parameters, wherein trial‐and‐error or empirical methods are often used to select the parameters in source‐wasting and time‐consuming ways. Hence, there is a need to accelerate the development of advanced cutting techniques and novel modeling approaches in the food‐manufacturing industry. Recently, advanced cutting techniques (ultrasonic vibration‐assisted [UVA], laser, and waterjet cutting) are seen to be superior in processing foods of various textures, with the advantages of high cutting quality, low contamination, and easy operation. Compared with conventional cutting, advanced cutting techniques can dramatically reduce cutting force and energy consumption, resulting in high efficiency, energy‐and‐source saving, and low carbon footprint. Additionally, the finite element (FE) model does simulate the cutting process well, and artificial intelligence (AI) technology is competent to optimize the cutting parameters. This review is perhaps the first one focusing on the advanced cutting techniques applied in the food industry, serving as a summary of the cutting mechanisms, critical influence factors, and applications of conventional and advanced cutting techniques including UVA, laser, and waterjet cutting. In addition, the modeling approaches with respect to FE and AI models are emphasized. Finally, the challenges and future perspectives of advanced cutting techniques combined with modeling approaches are highlighted, and those approaches are promising in the future intelligent food‐manufacturing industry.
Practical Application
The review clearly demonstrates that advanced cutting techniques as having advantages such as high efficiency, energy‐and‐source saving, and low damages, thus exhibiting great potential in processing food of various textures with high cutting quality, low contamination, and easy operation. Additionally, the FE model does simulate the cutting process well and AI is competent in optimizing the cutting parameters, which possesses great potential in providing comprehensive cutting information and selecting the optimal combination of cutting parameters.
Ultrasound is a well-known technology to develop various effective, efficient, and reliable processing applications in the food industry. Ultrasound is a versatile technology and has been applied efficiently in food processes including extraction, drying, decontamination, mixing and homogenization, emulsification, freezing, thawing, and cutting of food. Some of the advantages of using ultrasound for food processing faster energy and mass transfer, shorter processing times, higher product yields, simpler equipment design, low processing costs and/or maintenance costs, flexibility to combine with other processes, and possibly reduced environmental footprints. This chapter presents current knowledge and application of ultrasound-assisted processes (excluding extraction) in bio-marine sector.
Background
The considerable demand for high-quality foods derives us to adapt and adopt novel automated technologies in order to reduce waste and increase nutrition and sensory quality of processed foods. The emerging area of laser-based technology has shown significant potential to enhance the quality and safety of foods due to the better monochromaticity and directivity of laser beams. Base on the applications of lasers in food packaging and food detection, laser-assisted food processing is a growing area arousing considerable interest among scientists in the past decade.
Scope and approach
This review critically evaluates relevant literatures to address the potential for laser technology applied to food processing. The key to the success of laser-assisted food processing is outlined and analyzed from the perspective of properties of both lasers and food materials. Aspects of processing mechanism via laser technology and application are discussed. The corresponding problems and future prospects for laser-assisted food processing are discussed along with research and development needs.
Key findings and conclusions
Base on thermal and photochemical process, lasers display great potential in the field of food processing including material pretreatment, drying, cooking, microbial inhibition, laser marking, extraction, fermentation and aging of liquid foods etc. The operational parameters of lasers and optical and thermal properties of the targeted material affect the quality of the products. To adapt current laser technology to industrial food processing it is necessary to offset some limitations, especially the control of thermal damage, establishment of mathematical models/databases, and automatic and safety processing equipment.
Constantly sharp knives have applications in industrial cutting, clean shaving, and precision surgery. With the purpose of increasing blade sharpness, an ultrasonic knife was built, operating at 134-kHz continuous ultrasound with an average temperature increase of 0.4 °C at the blade. The sharpness of the incisions made to a sheet of plain printer paper with a blunted blade under sonication were compared to those of the same blade without sonication and to industrially cut paper edges. The incisions from the sonicated blade were visibly sharper than those from the unsonicated blade, and at least as sharp as those from the industrially cut paper edge.
The aim of this study was to investigate the effect of the ultrasound‐assisted microwave vacuum frying (USMVF) technology on the quality parameters of pumpkin slices. Pumpkin slices fried for 15 min by different frying methods, such as USMVF, microwave‐assisted vacuum frying (MVF), and vacuum frying (VF), were compared in terms of parameters such as moisture content, oil content, color, texture, and microstructure. During the frying process, the effect of microwave powers (600 W, 800 W, and 1,000 W) and ultrasound powers (0 W, 300 W, and 600 W) was evaluated and compared with the conventional VF. The results showed that the application of ultrasound lowered the moisture content significantly (p < .05) in comparison to MVF and VF samples. The application of ultrasound also positively affected the oil content (low oil absorption) and texture (better crispness) of USMVF samples. Cellular structure of pumpkin chips was also preserved well when ultrasound‐assisted frying process. Color was not significantly influenced by applying ultrasound. In summary, the microwave and ultrasound applied in the VF process showed a synergistic effect in promoting the quality parameters of pumpkin chips.
Practical applications
The results showed that the application of ultrasound lowered the moisture content significantly in comparison to microwave‐assisted vacuum frying and vacuum frying (VF) samples. The application of ultrasound also positively affected the oil content (lower oil absorption) and texture (better crispness) of ultrasound‐assisted microwave vacuum frying (USMVF) samples. Microstructure of pumpkin chips was also preserved well when ultrasound‐assisted frying process. Color was not significantly influenced by applying ultrasound. In summary, the microwave and ultrasound applied in the VF showed a synergistic effect in promoting quality parameters of pumpkin chips.
The less-invasive non-embedded cell cutting or slicing technique provides opportunities for a bio-study at subcellular scale, but there are few effective solutions available at the current stage. This paper reports a robot-aided vibrating system for less-invasive non-embedded cell cutting and investigates the role of key vibrating parameters in the cell cutting process. First, a nanoknife with sharp angle 5° is fabricated from a commercial atomic force microscope cantilever by focused ion beam etching and a vibrating system is constructed from a piezo actuator. Then, they are integrated with a self-developed nanorobotic manipulation system inside an environment scanning electron microscope. After that, we choose yeast cells as the sample to implement the vibrating cutting and investigate the effect of vibrating parameters (frequency and amplitude) on cell cutting quality. The results clearly indicate that the vibrating nanoknife is able to reduce the cutting force and improve the cutting quality. It is also suggested that the repeated load-unload (impact) cycle is the main reason for the better performance of vibrating cutting. The effect of vibrating parameters at small scale benefits our fundamental understanding on cell mechanics, and this research paves a way for the low-destructive non-embedded cell cutting and promotes the practical cell cutting techniques.
Size reduction of solid foods and emulsification or homogenisation of liquid foods are used to change their organoleptic characteristics and their suitability for further processing. This chapter describes the theory of size reduction, the equipment used for milling, slicing, dicing, pulping and homogenisation, and the effects of processing on foods and microorganisms.
Acoustic energy as a form of physical energy has drawn the interests of both industry and scientific communities for its potential use as a food processing and preservation tool. Currently, most such applications deal with ultrasonic waves with relatively high intensities and acoustic power densities and are performed mostly in liquids. In this review, we briefly discuss the fundamentals of power ultrasound. We then summarize the physical and chemical effects of power ultrasound treatments based on the actions of acoustic cavitation and by looking into several ultrasound-assisted unit operations. Finally, we examine the biological effects of ultrasonication by focusing on its interactions with the miniature biological systems present in foods, i.e., microorganisms and food enzymes, as well as with selected macrobiological components. Expected final online publication date for the Annual Review of Food Science and Technology Volume 5 is February 28, 2014. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Applications involving high-power ultrasound are expanding rapidly as ultrasonic intensification opportunities are identified in new fields. This is facilitated through new technological developments and an evolution of current systems to tackle challenging problems. It is therefore important to continually update both the scientific and commercial communities on current system performance and limitations. To achieve this objective, this paper addresses two key aspects of high-power ultrasonic systems. In the first part, the review of high-power applications focuses on industrial applications and documents the developing technology from its early cleaning applications through to the advanced sonochemistry, cutting, and water treatment applications used today. The second part provides a comprehensive overview of measurement techniques used in conjunction with high-power ultrasonic systems. This is an important and evolving field which enables design and process engineers to optimize the behavior and/or operation of key metrics of system performance, such as field distribution or cavitation intensity.
In the food industry, ultrasonic cutting is applied to improve the quality of food segments by a reduction of the cutting force. This improvement is achieved by a modification of tool-workpiece interactions as the movement of the cutting device is superpositioned with ultrasonic excitation. The power consumption of the ultrasonic assembly depends on vibration amplitude and frequency, and on loading conditions during operation. Therefore the power delivered by the generator increases from the no-load status when cutting starts. In this study the influence of ultrasonic parameters, cutting velocity and the cutting material itself on the power demand of the ultrasonic generator was examined, and cutting force was recorded to verify power–force interrelations. Generally, the food properties showed a significant impact on power demand and energy consumption, but did not correlate with the reduction of cutting force. An increase of the vibration amplitude increases both the no-load power – the power necessary to maintain blade vibration in air – and the load share, i.e., the material-dependent fraction of the power consumption of the vibrating device. Higher frequencies lead to higher power demands when cutting with comparable maximum vibration speed. The reduction of ultrasonic cutting time by applying higher cutting velocities results in a reduced energy consumption. Hence, for an optimization of the vibration parameters during ultrasonic cutting the impact of the materials should be taken into account.
Cutting with devices excited by ultrasound is a promising alternative to conventional cutting when the materials contain particles which differ in stiffness and elasticity from the surrounding bulk or when they consist of layers which exhibit largely differing mechanical properties. Aim of the present study was to evaluate the impact of ultrasonic excitation and blade inclination (slice-to-push ratio) on cutting forces and cutting work of different foods with a fast-moving device which was excited in a way that the direction of vibration was parallel to the edge of the blade. The results show that ultrasonic excitation significantly reduces cutting force, that the magnitude of cutting force reduction largely depends on the product, and that cutting force and cutting work increase with increasing cutting velocity. Whereas these interactions are because of the micro-saw movement of the cutting tool, it was not possible to explain the product-dependent response to blade inclination.
The effects of vertical cutting velocity and the magnitude of ultrasonic excitation on the reduction of the work necessary to separate various food materials were investigated. Generally, cutting work increased with increasing cutting velocity but, at each particular cutting velocity, decreased with increasing magnitude of the ultrasonic excitation of the cutting tool. Interactions between cutting velocity and the maximum vibration speed at the cutting edge, which is determined by both excitation amplitude and excitation frequency, are significant. Depending on the food under action, the relative amount of cutting work reduction is either affected by the maximum vibration speed or, additionally, by vertical cutting velocity. No distinct effects of the excitation frequency (20 or 40 kHz) were observed.
Eight cheese varieties with different moisture (357–488gkg−1), fat (183–335gkg−1) and protein content (202–292gkg−1) were subjected to ultrasonic cutting using a 40kHz guillotine sonotrode. Cutting force curves were evaluated with respect to ultrasound-induced cutting work reduction and energy demand of the sonotrode. With cutting velocity and ultrasonic amplitude set to 2500mmmin−1 and 12μm, respectively, composition had a significant effect on the response of the cheeses. Whereas cutting work reduction was mainly determined by fat-in-dry matter, the energy demanded by the sonotrode to maintain vibration was inversely interrelated to the ratio of moisture to solids-non-fat. Three selected cheeses were subjected to cutting experiments with systematically varied cutting velocity and amplitude. The results indicate that the cheeses respond differently to the cutting parameters, and that their careful adjustment is helpful for a target-orientated design of the process.
There are a lot of food products where conventional cutting techniques provide an insufficient processing quality. Several problems could be solved or diminished using ultrasonic cutting technology. However, the prediction of special effects of ultrasound within the foodstuff is very difficult. Therefore, currently extensive pilot studies are widely used for process evaluation. The intention of the investigations presented in this paper was to establish an overview of suitable applications and recommendations for process parameters. Criteria for suitability of ultrasonic cutting based on structural and textural properties are proposed as a result of systematic investigations of foods and model substances.
Cutting with tools excited by ultrasound is increasingly applied in the food industry, especially for cheese, confectionary, and bakery products. Due to the lack of a thorough understanding of the separation process, most of the ultrasonic cutting systems are designed and applied on the basis of empirical knowledge. The aim of the study was to elaborate the impact of ultrasonic parameters, that is, amplitude and frequency, on the cutting process, and special emphasis was placed on resulting effects in the close vicinity of the cutting edge, which are reflected by the separation forces. To allow a direct investigation of the mechanical separation without artifacts due to secondary effects such as melting and cavitation, the crumb of different bakery products (for example, dark and white bread, yeast dumplings, and cake) were analyzed. The results show that the influence of ultrasonic amplitude and frequency can be expressed by the maximum vibration speed on the cutting edge. For each product, an increasing maximum vibration speed results in a particular reduction of the cutting force and an increased quality of the cut. The magnitude of the cutting force reduction is inversely related to a material-specific parameter cx, which was calculated from the mechanical properties according to the speed-of-sound concept. Therefore, the determination of cx allows a specific adjustment of ultrasonic amplitude and frequency to achieve optimum cutting quality.
Investigations into parameters affecting cutting forces in foods were undertaken to identify basic trends such as the relationship of cutting forces to cutting speeds and food temperatures. A simple plain blade was used to cut three typical foodstuffs (cheese, bacon and beef) at three feed speeds and three temperatures. After each cut the blade was passed through the product a second time to measure forces indicative of friction on the sides of the blade.Cutting forces for cheese decreased with increasing temperature and increased with cutting speed. The relatively homogeneous nature of the samples resulted in consistent and repeatable measurements. For bacon, variable salt content gave rise to different ice contents and thus hardnesses in samples at the same ‘frozen’ temperatures. Layers of fat and muscle boundaries also produced marked deviations from the average forces. Force results were therefore scattered but increased with decreasing temperature. The effect of cutting speed was not consistent for all forces, but higher speeds generally produced higher forces. For beef, there was a marked difference between frozen and unfrozen samples but little difference between samples at different unfrozen temperatures. In unfrozen samples, cutting speed had little effect on forces, whereas faster cutting speeds produced higher forces in frozen samples. The proportion of total cutting forces made up by friction was found to be consistent over all temperatures and speeds for cheese and bacon, but markedly higher in the frozen beef samples compared to the unfrozen samples.
The effect of ultrasonic treatments on Alicyclobacillus acidoterrestris in apple juice was investigated. In general, inactivation of the cells was more pronounced at an elevated power level and as the processing time increased. Approximately 60% of the cells were inactivated after treating the apple juice with 300-W ultrasound for 30 min. The reduction reached more than 80% when the juice was processed for 60 min. The linear inactivation rates (D values) of ultrasound on A. acidoterrestris were both process- and strain-dependent. The lowest D value at 36.18 min was found when using 600-W ultrasound to treat the A30 strain isolated from the air of a commercial apple juice processing plant, whereas the strain isolated from apple juice concentrate was found most resistant against ultrasound. Changes of sugar content, acidity, haze and juice browning were noted after ultrasonic treatments but did not adversely alter the juice quality.
Characterization of the effects of ultrasonic treatments on thermoacidophilic Alicyclobacillus acidoterrestris provides better understanding of how ultrasound technology could assist in alleviating the hard-to-detect spoilage caused by this spore former. Although ultrasonic technology might not be suitable as a standalone unit operation to inactivate high cell loads, the process could be integrated with other thermal or nonthermal technologies to enhance processing efficiencies, consequently preventing microbial spoilage caused by A. acidoterrestris.
It was often observed that friction forces can be reduced significantly if ultrasonic oscillations are superposed to the
macroscopic sliding velocity. This phenomenon can be used to improve machining processes by addition of ultrasonic vibration
to tools or workpieces, and forms the basis for many processes of ultrasonic machining. On the other hand, ultrasonic vibrations
can be used to generate motion. The thrusting force of ultrasonic motors is provided to the rotor through friction. In the
present paper, a simple theoretical model for friction in the presence of ultrasonic oscillations is derived theoretically
and validated experimentally. The model is capable of predicting the reduction of the macroscopic friction force as a function
of the ultrasonic vibration frequency and amplitude and the macroscopic sliding velocity.
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.
Ductile machining of brittle materials, even at a high critical depth-of-cut, has been realised by applying ultrasonic vibration
to a diamond tool tip. A surface roughness Ra of 100 nm at a 2 μm depth-of-cut was achieved. A discussion on fundamental principles
of ultrasonic machining, the material removal mechanism and the calculation of critical factors are presented in this paper.
In the food industry, ultrasonic cutting is used to improve separation by a reduction of the cutting force. This reduction can be attributed to the modification of tool-workpiece interactions at the cutting edge and along the tool flanks because of the superposition of the cutting movement with ultrasonic vibration of the cutting tool. In this study, model experiments were used to analyze friction between the flanks of a cutting tool and the material to be cut. Friction force at a commercial cutting sonotrode was quantified using combined cutting-friction experiments, and sliding friction tests were carried out by adapting a standard draw-off assembly and using an ultrasonic welding sonotrode as sliding surface. The impact of material parameters, ultrasonic amplitude, and the texture of the contacting food surface on friction force was investigated. The results show that ultrasonic vibration significantly reduces the sliding friction force. While the amplitude showed no influence within the tested range, the texture of the contact surface of the food affects the intensity of ultrasonic transportation effects. These effects are a result of mechanical interactions and of changes in material properties of the contact layer, which are induced by the deformation of contact points, friction heating and absorption heating because of the dissipation of mechanical vibration energy.
Qualitative process evaluation for ultrasonic cutting of food
- Schneider
Ultrasonic cutting of cheese and apples-effect on quality attributes during storage
- G Yildiz