Ultrasound-assisted modification of functional properties and biological activity of biopolymers: A review

In this review, the recent applications of power ultrasound technology in improving the functional properties and biological activities of biopolymers are reviewed. The basic principles of ultrasonic technology are briefly introduced, and its main effects on gelling, structural, textural, emulsifying, rheological properties, solubility, thermal stability, foaming ability and foaming stability and biological activity are illustrated with examples reviewing the latest published research papers. Many positive effects of ultrasound treatment on these functional properties of biopolymers have been confirmed. However, the effectiveness of power ultrasound in improving biopolymers properties depends on a variety of factors, including frequency, intensity, duration, system temperature, and intrinsic properties of biopolymers such as macromolecular structure. In order to obtain the desired outcomes, it is best to apply optimized ultrasound processing parameters and use the best conditions in terms of frequency, amplitude, temperature, time, pH, concentration and ionic strength related to the inherent characteristics of each biopolymer. This will help employ the full potential of ultrasound technology for generating innovative biopolymers functionalities for various applications such as food, pharmaceuticals, and other industries.     

Effects of ultrasound on the techno-functional properties of milk proteins: A systematic review

Techno-functional properties of proteins, including foaming capacity, water holding capacity, solubility, emulsifying properties, and gelling formation, are known to play an important role in food processing technologies and be considered significant contributors in the development of new food products. In recent years, research has proven that ultra-sonication can influence the techno-functional properties of proteins through modification of their molecular structure. In this study, Scopus, Web of Science, PubMed, Google Scholar, ProQuest, and FSTA (Food Science and Technology Abstracts) databases were searched to find all related articles from 2000 to 2021. The results showed that the improving effects of ultrasound on each of the functional properties of proteins is entirely dependent on the ultrasound conditions and the type of ultrasound-treated protein. The results of functional parameters of milk proteins also showed that ultrasound could modify these properties. However, further studies are required to reach conclusive results that permit the employment of ultrasound to improve the techno-functional properties of milk proteins.     

Effects of ultrasound pretreatment on functional property,antioxidant activity,and digestibility of soy protein isolate nanofibrils

Nanofibrils, an effective method to modulate the functional properties of proteins, can be promoted by ultrasound pretreatment. This study investigated the effect of ultrasound pretreatment on the structure, functional property, antioxidant activity and digestibility of soy protein isolate (SPI) nanofibrils. The results showed that high amplitude ultrasound had a significant effect on structure of SPI nanofibrils. SPI nanofibrils pretreated by 80% amplitude ultrasound showed a blueshift of the amide II band in Fourier transform infrared spectroscopy (FTIR), resulted in more tryptophan residues being buried and increased the crystallinity. Low amplitude ultrasound (20%) pretreatment significantly improved the solubility, emulsifying activity index (EAI) and water absorption capacity (WAC) of SPI nanofibrils, but 80% amplitude ultrasound pretreatment of SPI nanofibrils reduced emulsifying stability index (ESI). High amplitude ultrasound (60% and 80%) pretreatment of SPI nanofibrils improved the foaming capacity and foaming stability and decreased denaturation temperature. DPPH radical scavenging activity of SPI nanofibrils were significantly improved by ultrasound pretreatment. 20% amplitude ultrasound pretreatment improved DPPH, ABTS radical scavenging activity and ferric reducing antioxidant power of SPI nanofibrils. The digestion rate of 80% amplitude ultrasound-pretreated nanofibrils were consistently higher, and SPI nanofibrils pretreated by ultrasound were more fragmented and shorter after simulating gastrointestinal digestion. This study would expand the application of food-grade protein nanofibrils in the food industry.     

Recent advances in the application of ultrasound in dairy products: Effect on functional,physical, chemical,microbiological and sensory properties

Alternative methods for improving traditional food processing have increased in the last decades. Additionally, the development of novel dairy products is gaining importance due to an increased consumer demand for palatable, healthy, and minimally processed products. Ultrasonic processing or sonication is a promising alternative technology in the food industry as it has potential to improve the technological and functional properties of milk and dairy products. This review presents a detailed summary of the latest research on the impact of high-intensity ultrasound techniques in dairy processing. It explores the ways in which ultrasound has been employed to enhance milk properties and processes of interest to the dairy industry, such as homogenization, emulsification, yogurt and fermented beverages production, and food safety. Special emphasis has been given to ultrasonic effects on milk components; fermentation and spoilage by microorganisms; and the technological, functional, and sensory properties of dairy foods. Several current and potential applications of ultrasound as a processing technique in milk applications are also discussed in this review.     

Effect of ultrasound on the techno-functional properties of food components/ingredients: A review

Ultrasound (US) has been used in many food systems and model systems, such as starch, whey protein concentrates and soy, to modify their chemical and techno-functional properties. At present, the use of ultrasound has yielded diverse results, ranging from potentiating the technological and functional properties of various foods to different operating conditions. Similarly, the results that were obtained vary according to the ultrasonic equipment used and the power, frequency and times of sonication, as well as the characteristics of the food system used. However, not all results have been favourable because US can cause damage to the structure of some food components, such as starch, and affect the technological and functional properties of the food. In the literature, there is little research on the effect of sonication on fibre; this gap in the literature is worrisome because fibre is found in a wide variety of foods and provides health benefits. Such research would represent an opportunity for researchers to make use of this technology for the generation of knowledge and improve the techno-functional properties in fibre, which could benefit the human population and the food industry. In this review, we present current results obtained with US in different treatments affecting processes of strong importance in the food industry, emphasizing the effects in the different model systems.     

Sustainable emerging high-intensity sonication processing to enhance the protein bioactivity and bioavailability: An updated review

High-intensity ultrasound (HIU) is considered one of the promising non-chemical eco-friendly techniques used in food processing. Recently (HIU) is known to enhance food quality, extraction of bioactive compounds and formulation of emulsions. Various foods are treated with ultrasound, including fats, bioactive compounds, and proteins. Regarding proteins, HIU induces acoustic cavitation and bubble formation, causing the unfolding and exposure of hydrophobic regions, resulting in functional, bioactive, and structural enhancement. This review briefly portrays the impact of HIU on the bioavailability and bioactive properties of proteins; the effect of HIU on protein allergenicity and anti-nutritional factors has also been discussed. HIU can enhance bioavailability and bioactive attributes in plants and animal-based proteins, such as antioxidant activity, antimicrobial activity, and peptide release. Moreover, numerous studies revealed that HIU treatment could enhance functional properties, increase the release of short-chain peptides, and decrease allergenicity. HIU could replace the chemical and heat treatments used to enhance protein bioactivity and digestibility; however, its applications are still on research and small scale, and its usage in industries is yet to be implemented.     

A review of recent advances in the decontamination of mycotoxin and inactivation of fungi by ultrasound

Innovative technologies for the pasteurization of food products have increased due to the global demand for higher-quality food products. In this regard, the current article aimed to provide an overview regarding the latest research on US application in the decontamination of fungi in food products and highlight the parameters influencing the effectiveness of this method. Therefore, the related article with inactivation of fungi and mycotoxins by ultrasound among last four years (2018–2021) by using terms such as 'mycotoxin,' 'inactivation,' 'ultrasound,' 'decontamination' among some international databases such as PubMed, Web of Science, Embase and Google Scholar“ was retrieved. Ultrasound (US) is considered a non-thermal decontamination method for food products. In US, the release of energy due to the acoustic phenomenon destroys microorganisms. This technology is advantageous as it is inexpensive, eco-friendly, and does not negatively affect food products' food structure and organoleptic properties. The influence of the US on food structure and organoleptic properties dramatically depends on the intensity and energy density applied In addition, it can preserve higher levels of ascorbic acid, lycopene, and chlorophyll in sonicated food products. The treatment conditions, including frequency, intensity, duration, temperature, and processing pressure, influence the effectiveness of decontamination. However, US displays synergistic or antagonistic effects on bacteria, yeasts, molds, and mycotoxins when combined with other types of decontamination methods such as chemical and thermal approaches. Thus, further research is needed to clarify these effects. Overall, the application of US methods in the food industry for decreasing the microbial content of food products during processing has been applied. However, the use of US with other techniques needs to be studied further.     

Effect mechanism of ultrasound pretreatment on fibrillation Kinetics,physicochemical properties and structure characteristics of soy protein isolate nanofibrils

Self-assembly of soy proteins into nanofibrils is gradually considered as an effective method to improve their technical and functional properties. Ultrasound is a non-thermal, non-toxic and environmentally friendly technology that can modulate the formation of protein nanofibrils through controlled structural modification. In this research, the effect of ultrasound pretreatment on soy protein isolate nanofibrils (SPIN) was evaluated by fibrillation kinetics, physicochemical properties and structure characteristics. The results showed that the optimum ultrasound condition (20% amplitude, 15 min, 5 s on-time and 5 s off-time) could increase the formation rate of SPIN by 38.66%. Ultrasound reduced the average particle size of SPIN from 191.90 ± 5.40 nm to 151.83 ± 3.27 nm. Ultrasound could increase the surface hydrophobicity to 1547.67 in the initial stage of nanofibrils formation, and extend the duration of surface hydrophobicity increased, indicating ultrasound could expose more binding sites, creating more beneficial conditions for nanofibrils formation. Ultrasound could change the secondary and tertiary structure of SPIN. The reduction of α-helix content of ultrasound-pretreated soy protein isolate nanofibrils (USPIN) was 12.1% (versus 5.3% for SPIN) and the increase of β-sheet content was 5.9% (versus 3.5% for SPIN) during fibrillation. Ultrasound could accelerate the formation of SPIN by promoting the unfolding of SPI, exposure of hydrophobic groups and formation of β-sheets. Microscopic images revealed that USPIN generated a curlier and looser shape. And ultrasound reduced the zeta potential, free sulfhydryl groups content and viscosity of SPIN. SDS-PAGE results showed that ultrasound could promote the conversion of SPI into low molecular weight peptides, providing building blocks for the nanofibrils formation. The results indicated that ultrasound pretreatment could be a promising technology to accelerate SPIN formation and promote its application in food industry, but further research is needed for the improvement of the functional properties of SPIN.     

REVIEW: High pressure NMR study of proteins – seeking roots for function,evolution, disease and food applications

NMR experiments at variable pressure reveal a wide range of conformation of a globular protein spanning from within the folded ensemble to the fully unfolded ensemble, herewith collectively called “high-energy conformers”. The observation of “high-energy conformers” in a wide variety of globular proteins has led to the “volume theorem”: the partial molar volume of a protein decreases with the decrease in its conformational order. Since “high-energy conformers” are intrinsically more reactive than the basic folded conformer, they could play decisive roles in all phenomena of proteins, namely function, environmental adaptation and misfolding. Based on the information on high-energy conformers and the rules on their partial volume in its monomeric state and amyloidosis, one may have a general view on what is happening on proteins under pressure. Moreover, one may even choose a high-energy conformer of a protein with pressure as variable for a particular purpose. Bridging “high-energy conformers” to macroscopic pressure effects could be a key to success in pressure application to biology, medicine, food technology and industry in the near future.     

Application of ultrasound technology in processing of ready-to-eat fresh food: A review

With the increase in food standardization and the pace of modern life, the demand for ready-to-eat foods is growing. The strong processing conditions of traditional technology often accelerate the rate of deterioration of quality, and microbes are the safety hazard of ready-to-eat foods. Ultrasound technology is an environmentally friendly technology that hardly causes thermal damage to raw materials. In this paper, the ultrasound technology is used in the disinfection, sterilization, enzyme inactivation, desensitization, dehydration, curing, tenderization and cooking process of fresh food from the perspective of microbial safety and quality of fresh food. The cavitation effect of ultrasound can improve the mass transfer rate of infiltration processes such as dehydration and curing, promote the oxidation of lipids and proteins for enrich the flavor of meat products, improve the microbiological safety and reduce the sensitization by destroying the integrity of the microbial cells and the conformation of the protein. In addition, ultrasound as an auxiliary processing technology can reduce the damage of traditional production technology to reserve the quality and nutritional value of food. Ultrasound has proved to be an efficient and green processing technology for ready-to-eat food.     

Structural and physicochemical properties of the different ultrasound frequency modified Qingke protein

There is a burgeoning demand for modified plant-based proteins with desirable physicochemical and functional properties. The cereal Qingke is a promising alternative protein source, but its use has been limited by its imperfect functional characteristics. To investigate the effect of ultrasound treatment on Qingke protein, we applied single- (40 kHz), dual- (28/40 kHz), and tri- (28/40/50 kHz) frequency ultrasound on the isolated protein and measured subsequent physicochemical and structural changes. The results showed that the physicochemical properties of proteins were modified following ultrasound treatment, and many of these changes significantly increased with increasing frequency. Compared with the native Qingke protein (control), the solubility, foaming activity, stability, and water or oil holding capacity of tri-frequency ultrasound modified Qingke protein increased by 43.54%, 20.83%, 20.51%, 28.9%, and 45.2%, respectively. Furthermore, ultrasound treatment altered the secondary and tertiary structures of the protein resulting in more exposed chromophoric groups and inner hydrophobic groups, as well as reduced β-sheets and increased random coils, relative to the control. Rheological and texture characterization indicated that the values of G' and G'', hardness, gumminess, and chewiness decreased after ultrasound treatment. This study could provide a theoretical basis for the application of multi-frequency ultrasonic technology for modification of Qingke protein to expand its potential use as an alternative protein source.     

Ultrasound-assisted processing: Science,technology and challenges for the plant-based protein industry

The present-day consumer is not only conscious of the relationship between food consumption and positive health, but also keen on environmental sustainability. Thus, the demand for plant-based proteins, which are associated with nutrition and environmental sustainability. However, the plant-based protein industry still demands urgent innovation due to the low yield and long extraction time linked with traditional extraction methods. Although ultrasound is an eco-innovative technique, there exist limited data regarding its impact with plant-based protein. In this paper, the scientific principles of ultrasonication with regards to its application in plant-based protein research were reviewed. After comparing the cavitational and shearing impacts of different ultrasonic parameters, the paper further reviewed its effects on extracted protein characteristics and techno-functional properties. Additionally, current technological challenges and future perspectives of ultrasonication for the plant-based protein industry were also discussed. In summary, this review does not only present the novelty and environmental sustainability of ultrasound as a plant-based protein assisted-extraction method, but also highlights on the correlation between protein source, structure and subsequent functional properties which are important crucial factors for maximum application of ultrasound in the growing plant-based protein market.     

Application of ultrasound technology in the drying of food products

This study presents a state-of-the-art overview on the application of ultrasound technology in the drying of food products, including the ultrasound pre-treatment and ultrasound assisted drying. The effect of main parameters and ultrasound technology on the drying kinetics and food quality were discussed. Inconsistencies were pointed out and analyzed in detail. Results showed that for ultrasound pre-treatment, the food products may lose or gain water and increase of ultrasonic parameters (sonication time, amplitude and ultrasound power) promoted the water loss or water gain. When ultrasound technology was applied prior to drying, an increase in drying kinetics was always observed, though some different results were also presented. For ultrasound assisted drying, the ultrasound power always gave a positive effect on the drying process, however, the magnitude of ultrasound improvement was largely dependent on the process variables, such as air velocity, air temperature, microwave power and vacuum pressure, etc. The application of ultrasound technology will somehow affect the food quality, including the physical and chemical ones. Generally, the ultrasound application can decrease the water activity, improve the product color and reduce the nutrient loss.     

High intensity ultrasound treatment of protein isolate extracted from dephenolized sunflower meal: Effect on physicochemical and functional properties

The influence of high intensity ultrasound (HIUS) on physicochemical and functional properties of sunflower protein isolates was investigated. Protein solutions (10% w/v) were treated with ultrasound probe (20 kHz) and ultrasound bath (40 kHz) for 5, 10, 20 and 30 min. Thermal stability of protein isolates was reduced as indicated by differential scanning calorimetry. Minimum thermal stability was observed at 20 min of sonication and increased further with increase in treatment time indicating aggregation at prolonged sonication. SDS-PAGE profile of proteins showed a significant reduction in molecular weight. Further, surface hydrophobicity and sulfhydryl content increased after HIUS treatment indicating partial unfolding of proteins and reduction in the intermolecular interactions. The particle size analysis showed that HIUS treatment reduced the particle size. Less turbid solution were observed largely due to reduction in particle size. HIUS decreased the available lysine content in protein isolates. Solubility, emulsifying capacity, emulsion stability, foaming capacity, foam stability and oil binding capacity were improved significantly, while as, water binding capacity was decreased. The effect of HIUS on physicochemical and functional properties of sunflower protein isolates was more pronounced in probe sonication rather than bath sonication. Protein isolates with improved functional properties can be obtained using high intensity ultrasound technology.     

Structural and functional modification of proteins from black soybean Aquasoya via ultrasonication

Plant-based proteins obtained from agricultural by-products have garnered growing interest in response to consumer awareness of health and environmental issues. This study aimed to improve the functionalities of the proteins recovered from black soybean Aquasoya (PBSA) by modifying their structure via ultrasonication. PBSA was ultrasonicated with a frequency of 40 kHz at 350 W for different time periods (0, 20, 40, and 60 min), and its structural characteristics, physicochemical properties, and functional properties were investigated. Ultrasonication left the primary structure intact but altered the secondary and tertiary structures of the PBSA; α-helix and β-sheet contents decreased, random coil contents increased, and buried non-polar amino acid residues were exposed. Moreover, ultrasound promoted an increase in free sulfhydryl content and a reduction in particle size. Consequently, functional properties, such as solubility, emulsion stability, and foaming performance were improved by modifying the structure and physicochemical properties of PBSA. This work demonstrates the potential of ultrasound, which is favorable for modifying the spatial conformation and related functionalities of proteins, thus meeting the needs of manufacturers to use function-enhanced proteins as food additives.     

Enhancement of convective drying by application of airborne ultrasound – A response surface approach

Drying is one of the oldest and most commonly used processes in the food manufacturing industry. The conventional way of drying is by forced convection at elevated temperatures. However, this process step often requires a very long treatment time, is highly energy consuming and detrimental to the product quality. Therefore, an investigation of whether the drying time and temperature can be reduced with the assistance of an airborne ultrasound intervention is of interest.Previous studies have shown that contact ultrasound can accelerate the drying process. It is assumed that mechanical vibrations, creating micro channels in the food matrix or keeping these channels from collapsing upon drying, are responsible for the faster water removal. In food samples, due to their natural origin, drying is also influenced by fluctuations in tissue structure, varying between different trials. For this reason, a model food system with thermo-physical properties and composition (water, cellulose, starch, fructose) similar to those of plant-based foods has been used in this study.The main objective was, therefore, to investigate the influence of airborne ultrasound conditions on the drying behaviour of the model food. The impact of airborne ultrasound at various power levels, drying temperature, relative humidity of the drying air, and the air speed was analysed. To examine possible interactions between these parameters, the experiments were designed with a Response Surface Method using Minitab 16 Statistical Software (Minitab Inc., State College, PA, USA). In addition, a first attempt at improving the process conditions and performance for better suitability and applicability in industrial scale processing was undertaken by non-continuous/intermittent sonication.     

High-intensity ultrasound-based process strategies for obtaining edible sunflower (Helianthus annuus L.) flour with low-phenolic and high-protein content

The sunflower Helianthus annuus L. represents the 4th largest oilseed cultivated area worldwide. Its balanced amino acid content and low content of antinutrient factors give sunflower protein a good nutritional value. However, it is underexploited as a supplement to human nutrition due to the high content of phenolic compounds that reduce the sensory quality of the product. Thus, this study aimed at obtaining a high protein and low phenolic compound sunflower flour for use in the food industry by designing separation processes with high intensity ultrasound technology. First, sunflower meal, a residue of cold-press oil extraction processing, was defatted using supercritical CO₂ technology. Subsequently, sunflower meal was subjected to different conditions for ultrasound-assisted extraction of phenolic compounds. The effects of solvent composition (water: ethanol) and pH (4 to 12) were investigated using different acoustic energies and continuous and pulsed process approaches. The employed process strategies reduced the oil content of sunflower meal by up to 90% and reduced 83% of the phenolic content. Furthermore, the protein content of sunflower flour was increased up to approximately 72% with respect to sunflower meal. The acoustic cavitation-based processes using the optimized solvent composition were efficient in breaking down the cellular structure of the plant matrix and facilitated the separation of proteins and phenolic compounds, while preserving the functional groups of the product. Therefore, a new ingredient with high protein content and potential application for human food was obtained from the residue of sunflower oil processing using green technologies.     

高能核物理实验国际合作研究近期代表性成果

高能核物理实验的主要物理目标是在极端高温度和能量密度条件下研究核物质新形态?夸克-胶子等离子体的产生及演化特性。深入揭示当前物质世界的深层次结构,以及强核力相互作用在高温、高密多粒子体系中的行为、特性。探寻在此极端条件下的新物理现象。本工作概述我国所参与的主要高能核物理实验国际合作研究项目及其物理目标。介绍我国在国际合作研究中所做出的近期代表性成果,以及我国在该领域研究中的新物理探究方面所取得的典型成就。并对高能核物理下一步的研究发展方向做出展望。     

Hybrid high-intensity ultrasound and microwave treatment: A review on its effect on quality and bioactivity of foods

With the growing of consumer’s demand for products ready to eat that can be elaborated with greener technologies without affecting to their organoleptic characteristics, the application of ultrasound combined with microwaves has been widely studied on food preservation treatments (drying, frying), extraction of high-value added compounds and enzymatic hydrolysis of proteins. This review presents a complete picture of current knowledge on the ultrasound combined with microwaves including the mechanisms, influencing factors, advantages and drawbacks, emphasising in several synergistic effects observed in different processes of strong importance in the food industry. Recent research has shown that this hybrid technology could not only minimise the disadvantages of power US for drying and frying but also improve the product quality and the efficiency of both cooking processes by lowering the energy consumption. Regarding extraction, current studies have corroborated that the combined method presents higher yields in less time, in comparison with those in the respective ultrasound and microwave separately. Additionally, recent results have indicated that the bioactive compounds extracted by this combined technology exhibit promising antitumor activities as well as antioxidant and hepatoprotective effects. Remarkably, this hybrid technology has been shown as a good pre-treatment since the structural changes that are produced in the molecules facilitate the subsequent action of enzymes. However, the combination of these techniques still requires a proper design to develop and optimized conditions are required to make a scale process, and it may lead to a major step concerning a sustainable development and utilization of bioactive compounds from natural products in real life.