The effect of ultrasound treatment on the structural, physical and emulsifying properties of dairy proteins

Effects of pH-shifting and ultrasound on the structural and emulsifying properties of peanut globulin fractions

This work investigated and compared the structural and emulsifying properties of peanut globulin fractions (conarachin and arachin) after ultrasonication (US) and pH2.5-shifting treatments, singly and in combination. Results showed that pH2.5-shifting was more effective in degrading peanut protein subunits and unfolding their structures than US treatment. Conarachin tended to aggregate during US and pH2.5-shifting treatments possibly due to higher free sulfhydryl content, while high molecular weight arachin tended to disaggregate during these treatments. pH2.5-shifting or US+pH2.5-shifting treatments significantly increased the surface hydrophobicity of conarachin (from 72 to 314) and arachin (from 336 to 888), which may be responsible for the enhancement of protein emulsifying activity. All treatments significantly improved the physical stability of arachin-stabilized emulsions with higher absolute potentials but lowered that of conarachin-stabilized emulsions. However, pH2.5-shifting or US+pH2.5-shifting treatments could improve the stability of conarachin-stabilized emulsions in the presence of salts.

Exploring the effect of protein secondary structure on the solid state and physical stability of protein-based amorphous solid dispersions

Amorphous solid dispersions (ASDs) using proteins as carriers have emerged as a promising strategy for stabilizing amorphous drug molecules. Proteins possess diverse three-dimensional structures that significantly influence their own properties and may also impact the properties of ASDs. We prepared β-lactoglobulin (BLG) with different contents of β-sheet and α-helical secondary structures by initially dissolving BLG in different mixed solvents, containing different ratios of water, methanol/ethanol, and acetic acid, followed by spray drying of the solutions. Our findings revealed that an increase in α-helical content resulted in a decrease in the glass transition temperature (Tg) of the protein. Subsequently, we utilized the corresponding mixed solvents to dissolve both BLG and the model drug celecoxib (CEL), allowing the preparation of ASDs containing either β-sheet-rich or α-helix/random coil-rich BLG. Using spray drying, we successfully developed BLG-based ASDs with drug loadings ranging from 10 wt% to 90 wt%. At drug loadings below 40 wt%, samples prepared using both methods exhibited single-phase ASDs. However, heterogeneous systems formed when the drug loading exceeded 40 wt%. At higher drug loadings, physical stability assessments demonstrated that the α-helix/random coil-rich BLG structure exerted a more pronounced stabilizing effect on the drug-rich phase compared to the β-sheet-rich BLG. Overall, our results highlight the importance of considering protein secondary structure in the design of ASDs.

Ultrasound modification on milk fat globule membrane and soy lecithin to improve the physicochemical properties, microstructure and stability of mimicking human milk fat emulsions

Starting from the consideration of the structure of human milk fat globule (MFG), this study aimed to investigate the effects of ultrasonic treatment on milk fat globule membrane (MFGM) and soy lecithin (SL) complexes and their role in mimicking human MFG emulsions. Ultrasonic power significantly affected the structure of the MFGM-SL complex, further promoting the unfolding of the molecular structure of the protein, and then increased solubility and surface hydrophobicity. Furthermore, the microstructure of mimicking MFG emulsions without sonication was unevenly distributed, and the average droplet diameter was large. After ultrasonic treatment, the droplets of the emulsion were more uniformly dispersed, the particle size was smaller, and the emulsification properties and stability were improved to varying degrees. Especially when the ultrasonic power was 300 W, the mimicking MFG emulsion had the highest encapsulation rate and emulsion activity index and emulsion stability index were increased by 60.88 % and 117.74 %, respectively. From the microstructure, it was observed that the spherical droplets of the mimicking MFG emulsion after appropriate ultrasonic treatment remain well separated without obvious flocculation. This study can provide a reference for the screening of milk fat globules mimicking membrane materials and the further utilization and development of ultrasound in infant formula.

Thermosonication as an effective substitution for fusion in Brazilian cheese spread (Requeijão Cremoso) manufacturing: The effect of ultrasonic power on technological properties

In this initial study, the impact of thermosonication as an alternative to the traditional fusion in Brazilian cheese spread (Requeijão Cremoso) manufacture was investigated. The effect of ultrasound (US) power was evaluated considering various aspects such as gross composition, microstructure, texture, rheology, color, fatty acid composition, and volatile compounds. A 13 mm US probe operating at 20 kHz was used. The experiment involved different US power levels (200, 400, and 600 W) at 85 °C for 1 min, and results were compared to the conventional process in the same conditions (85 °C for 1 min, control treatment). The texture became softer as ultrasound power increased from 200 to 600 W, which was attributed to structural changes within the protein and lipid matrix. The color of the cheese spread also underwent noticeable changes for all US treatments, and treatment at 600 W resulted in increased lightness but reduced color intensity. Moreover, the fatty acid composition of the cheese spread showed variations with different US power, with samples treated at 600 W showing lower concentrations of saturated and unsaturated fatty acids, as well as lower atherogenicity and thrombogenicity indexes, indicating a potentially healthier product. Volatile compounds were also influenced by US, with less compounds being identified at higher powers, especially at 600 W. This could indicate possible degradation, which should be evaluated in further studies regarding US treatment effects on consumer perception. Hence, this initial work demonstrated that thermosonication might be interesting in the manufacture of Brazilian cheese spread, since it can be used to manipulate the texture, color and aroma of the product in order to improve its quality parameters.

Effect of ultrasound combined with pineapple protease treatment on the tenderness of dried shrimp

BACKGROUND

In order to improve the tenderness of dried shrimp products as well as to reduce the hardness of the meat during the drying process, shrimp were treated with ultrasound combined with pineapple protease and the tenderization condition was optimized by measuring the texture and shear force of dried shrimp. In addition, the sulfhydryl content, myofibril fragmentation index (MFI) and microstructure were also examined to clarify the mechanisms of shrimp tenderization.

RESULTS

The results showed UB1 group with ultrasonic power of 100 W, heating temperature of 50 °C and pineapple protease concentration of 20 U mL-1 were the optimum tenderization conditions, where shrimp showed the lowest hardness (490.76 g) and shear force (2006.35 gf). Microstructure as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis results suggested that during the tenderization process the muscle segments of shrimps were broken, degradation of myofibrillar proteins occurred, and MFI values and total sulfhydryl content increased significantly (P < 0.05) (MFI value = 193.6 and total sulfhydryl content = 93.93 mmol mg-1 protein for UB 1 group).

CONCLUSION

Ultrasound combined with bromelain could be used as a simple and effective tenderization method for the production of tender dried shrimp. The best conditions were 100 W ultrasonic power, 50 °C ultrasonic temperature, and 20 U mL-1 bromelain. © 2024 Society of Chemical Industry.

Investigating the influence of protein secondary structure on the dissolution behavior of β-lactoglobulin-based amorphous solid dispersions

Proteins acting as carriers in amorphous solid dispersions (ASDs) demonstrate a notable sensitivity to the spray drying process, potentially leading to changes in their conformation. The main aim of this study was to investigate the dissolution performance of ASDs based on proteins with different content of secondary structures, specifically β-sheet and α-helix structures. We prepared β-sheet-rich and α-helix-rich β-lactoglobulin (BLG), along with corresponding ASDs containing 10 wt% and 30 wt% drug loadings, through spray drying using celecoxib as the model drug. Circular dichroism and Fourier Transform Infrared Spectroscopy results revealed that even though changes in secondary structure were obtained in the spray-dried powders, the BLGs exhibited reversibility upon re-dissolving in phosphate buffer with varying pH levels. Both β-sheet-rich BLG and α-helix-rich BLG exhibited enhanced dissolution rates and higher solubility in the media with pH values far from the isoelectric point (pI) of BLG (pH 2, 7, 8, and 9) compared to the pH closer to the pI (pH 3, 4, 5, and 6). Notably, the release rate and solubility of the drug and BLG from both types of BLG-based ASDs at 10 wt% drug loading were largely dependent on the solubility of pure SD-BLGs. α-helix-rich BLG-ASDs consistently exhibited equivalent or superior performance to β-sheet-rich BLG-ASDs in terms of drug release rate and solubility, regardless of drug loading. Moreover, both types of BLG-based ASDs at 10 wt% drug loading exhibited faster release rates and higher solubility, for both the drug and BLG, compared to the ASDs at 30 wt% drug loading in pHs 2, 7, and 9 media.

Effect of Ultrasonic Treatment on the Physicochemical Properties of Bovine Plasma Protein-Carboxymethyl Cellulose Composite Gel

In order to improve the stability of bovine plasma protein-carboxymethyl cellulose composite gels and to expand the utilization of animal by-product resources, this study investigated the impact of different ultrasound powers (300, 400, 500, 600, and 700 W) and ultrasound times (0, 10, 20, 30, and 40 min) on the functional properties, secondary structure and intermolecular forces of bovine plasma protein-carboxymethyl cellulose composite gel. The results showed that moderate ultrasonication resulted in the enhancement of gel strength, water holding capacity and thermal stability of the composite gels, the disruption of hydrogen bonding and hydrophobic interactions between gel molecules, the alteration and unfolding of the internal structure of the gels, and the stabilization of the dispersion state by electrostatic repulsive forces between the protein particles. The content of α-helices, β-turns, and β-sheets increased and the content of random curls decreased after sonication (p < 0.05). In summary, appropriate ultrasound power and time can significantly improve the functional and structural properties of composite gels. It was found that controlling the thermal aggregation behavior of composite gels by adjusting the ultrasonic power and time is an effective strategy to enable the optimization of composite gel texture and water retention properties.

Ultrasonic and homogenization: An overview of the preparation of an edible protein-polysaccharide complex emulsion

Emulsion systems are extensively utilized in the food industry, including dairy products, such as ice cream and salad dressing, as well as meat products, beverages, sauces, and mayonnaise. Meanwhile, diverse advanced technologies have been developed for emulsion preparation. Compared with other techniques, high-intensity ultrasound (HIUS) and high-pressure homogenization (HPH) are two emerging emulsification methods that are cost-effective, green, and environmentally friendly and have gained significant attention. HIUS-induced acoustic cavitation helps in efficiently disrupting the oil droplets, which effectively produces a stable emulsion. HPH-induced shear stress, turbulence, and cavitation lead to droplet disruption, altering protein structure and functional aspects of food. The key distinctions among emulsification devices are covered in this review, as are the mechanisms of the HIUS and HPH emulsification processes. Furthermore, the preparation of emulsions including natural polymers (e.g., proteins-polysaccharides, and their complexes), has also been discussed in this review. Moreover, the review put forward to the future HIUS and HPH emulsification trends and challenges. HIUS and HPH can prepare much emulsifier-stable food emulsions, (e.g., proteins, polysaccharides, and protein-polysaccharide complexes). Appropriate HIUS and HPH treatment can improve emulsions' rheological and emulsifying properties and reduce the emulsions droplets' size. HIUS and HPH are suitable methods for developing protein-polysaccharide forming stable emulsions. Despite the numerous studies conducted on ultrasonic and homogenization-induced emulsifying properties available in recent literature, this review specifically focuses on summarizing the significant progress made in utilizing biopolymer-based protein-polysaccharide complex particles, which can provide valuable insights for designing new, sustainable, clean-label, and improved eco-friendly colloidal systems for food emulsion. PRACTICAL APPLICATION: Utilizing complex particle-stabilized emulsions is a promising approach towards developing safer, healthier, and more sustainable food products that meet legal requirements and industrial standards. Moreover, the is an increasing need of concentrated emulsions stabilized by biopolymer complex particles, which have been increasingly recognized for their potential health benefits in protecting against lifestyle-related diseases by the scientific community, industries, and consumers.

Non-thermal techniques as an approach to modify the structure of milk proteins and improve their functionalities: a review of novel preparation

BACKGROUND

Milk proteins (MPs) have been widely used in the food industry due to their excellent functionalities. However, MPs are thermal-unstable substances and their functional properties are easily affected by heat treatment. Emerging non-thermal approaches (i.e., high-pressure homogenization (HPH), ultrasound (US), pulsed electric field (PEF)) have been increasingly popular. A detailed understanding of these approaches' impacts on the structure and functionalities of MPs can provide theoretical guidance for further development to accelerate their industrialization.

SCOPE AND APPROACH

This review assesses the mechanisms of HPH, US and PEF technologies on the structure and functionalities of MPs from molecular, mesoscopic and macroscopic levels, elucidates the modifications of MPs by these theologies combined with other methods, and further discusses their existing issues and the development in the food filed.

KEY FINDINGS AND CONCLUSIONS

The structure of MPs changed after HPH, US and PEF treatment, affecting their functionalities. The changes in these properties of MPs are related to treated-parameters of used-technologies, the concentration of MPs, as well as molecular properties. Additionally, these technologies combined with other methods could obtain some outstanding functional properties for MPs. If properly managed, these theologies can be tailored for manufacturing superior functional MPs for various processing fields.

Emulsifying properties of wheat germ protein: Effect of different ultrasonic treatment

The effect of ultrasonic treatment on emulsifying properties of wheat germ protein (WGP) was studied in this paper. WGP was subjected to low frequency (20 kHz), high intensity ultrasonic treatment at different power (200, 400, 600, 800 W) for 10 min, or different time (2, 4, 6, 8, 10, 15, 20 min) at 400 W. The emulsifying activity index and emulsion stability index of WGP were significantly improved, and the emulsion droplet was smaller and more uniform after ultrasound treatment. Ultrasound increased the adsorbed WGP concentration at the oil-water interface and reduced the interfacial tension, which explained the improved emulsifying properties of WGP. The investigation on molecular properties and protein conformation showed that ultrasound processing increased solubility, but decreased particle size and surface charge of WGP. Ultrasound processing resulted in the unfolding of the protein molecular structure indicated by the increase of surface hydrophobicity and surface free sulfhydryl group levels, and the decrease of intrinsic fluorescence intensity. Correlation analysis showed that the changes in WGP solubility, particle size, and surface hydrophobicity were the main driven factors for the improved emulsifying properties of WGP.

Effect of konjac oligo-glucomannan on emulsifying properties of myofibrillar protein

BACKGROUND

The high viscosity of konjac glumannan (KGM) limits its application in meat processing. In this work, the effects of konjac oligo-glucomannan (KOG), as a derivative of KGM, on the emulsifying properties of myofibrillar protein (MP) and the related mechanism were investigated.

RESULTS

It was found that the addition of KOG had no significant effect on the secondary structure of MP, but altered the tertiary conformation of MP, resulting in exposure of tyrosine residues to polar microenvironments and decreased intrinsic fluorescence intensity. In addition, the addition of KOG increased the emulsifying activity of MP, resulting in decreased particle size and improved physical stability of the emulsion. The emulsifying activity of MP reached the maximum value when 1.0 wt% KOG was added. Moreover, the interfacial tension and interfacially adsorbed protein content of MP/KOG emulsions decreased with the increase in KOG concentration.

CONCLUSION

These findings demonstrated that KOG mainly interacted with MP and changed the amphipathy of the KOG-MP at the oil-water interface, forming a stable interface film to improve the emulsifying properties of MP. © 2023 Society of Chemical Industry.

Characterization and utilization of soy protein isolate-(-)-epigallocatechin gallate-maltose ternary conjugate as an emulsifier for nanoemulsions: Enhanced physicochemical stability of the β-carotene nanoemulsion

In this study, a ternary conjugate was prepared by covalent bonding of protein, polysaccharide, and polyphenol via ultrasound and the Maillard reaction. Subsequently, the β-carotene nanoemulsion was prepared with the soy protein isolate-(-)-epigallocatechin gallate-maltose (SPI-EGCG-maltose) conjugate as the emulsifiers via ultrasound. The SPI-EGCG-maltose conjugate showed superior solubility, emulsification and foaming properties at 4 h reaction time. Meanwhile, the retention rates of β-carotene in the nanoemulsion after 30 d of storage, 8 h of light, and 55 °C of heat were >60%, >75%, and >60%, respectively. Furthermore, ultrasound treatment at 500 W for 10 min produced an inhibitory effect on the degradation of β-carotene. This study indicates that the nanoemulsion based on the ternary conjugate can effectively inhibit the β-carotene degradation by the external environment and prevent the oxidation and degradation of β-carotene in the nanoemulsion.

Effects of dual succinylation and ultrasonication modification on the structural and functional properties of ovalbumin

In this study, the functional properties of ovalbumin (OVA) were improved through dual modification with succinylation (succinylation degrees of 32.1 % [S1], 74.2 % [S2], and 95.2 % [S3]) and ultrasonication (ultrasonication durations of 5 min [U1], 15 min [U2], and 25 min [U3]), and the changes in protein structures were explored. Results showed that as the succinylation degree was increased, the particle size and surface hydrophobicity of S-OVA decreased by the maximum values of 2.2 and 2.4 times, respectively, causing emulsibility and emulsifying stability to increase by 2.7 and 7.3 times, respectively. After ultrasonic treatment, the particle size of succinylated-ultrasonicated OVA (SU-OVA) had decreased by 3.0-5.1 times relative to that of S-OVA. Moreover, the net negative charge of S3U3-OVA had increased to the maximum value of - 35.6 mV. These changes contributed to the further enhancement in functional indicators. The unfolding of the protein structure and the conformational flexibility of SU-OVA were illustrated and compared with those of S-OVA via protein electrophoresis, circular dichroism spectroscopy, intrinsic fluorescence spectroscopy, and scanning electron microscopy. The dually modified OVA emulsion (S3U3-E) presented small droplets (243.33 nm), reduced viscosity, and weakened gelation behavior that were indicative of even distribution, which was visually proven by confocal laser scanning microscopy images. Furthermore, S3U3-E exhibited favorable stability, a particle size that was almost unchanged, and a low polydispersity index (<0.1) over 21 days of storage at 4 °C. The above results demonstrated that succinylation combined with ultrasonic treatment could be an effective dual modification method for enhancing the functional performance of OVA.

Characterization of sonicated gluten protein and subsequent rheological properties of model dough and noodles

BACKGROUND

The present study aimed to investigate the effects of the thermo-mechanical and rheological properties of a wheat gluten-sonicated model dough and noodles, as well as the effects of ultrasonic frequency (20, 28, 40, 68 and 80 kHz) on the functional properties and structural features of gluten.

RESULTS

Water absorption, stability and developmental time, and viscoelastic behavior of gluten-sonicated model dough were all found to be improved. Water absorption, tensile resistance and stretching distance of noodles increased markedly, whereas cooking loss decreased. Ultrasonication at different frequencies also significantly affected gluten structure, including its surface hydrophobicity, micro-network structure, and secondary and tertiary structures. These alterations then caused changes in its functional characteristics. Compared to untreated gluten, sonicated gluten exhibited significantly increased oil and water capacities (8.75-15.26% and 100.65-127.71% higher than the untreated gluten, respectively), foaming and emulsifying properties, and increased solubility (63.46-98.83% higher than control). In addition, these findings indicated that 40 kHz was the likely resonance frequency of the cavitation bubble in the gluten solution. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis electropherograms revealed that such treatments did not affect the molecular weight of gluten, which was also consistent with its unchanged disulfide bond content.

CONCLUSION

The present study clarified the impact of frequency on the properties of gluten and model dough. The best frequency for modification of gluten was 40 kHz. Collectively, these findings suggest that ultrasonic technology has the potential for use in modifying wheat gluten and commercial noodle processing. © 2022 Society of Chemical Industry.

Effects of ultrasound on the structural and emulsifying properties and interfacial properties of oxidized soybean protein aggregates

Oxidative attack leads to the oxidative aggregation and structural and functional feature weakening of soybean protein. We aimed to investigate the impact of ultrasonic treatment (UT) with different intensities on the structure, emulsifying features and interfacial features of oxidized soybean protein aggregates (OSPI). The results showed that oxidative treatment could disrupt the native soy protein (SPI) structure by promoting the formation of oxidized aggregates with β1-sheet structures through hydrophobic interactions. These changes led to a decrease in the solubility, emulsification ability and interfacial activity of soybean protein. After low-power ultrasound (100 W, 200 W) treatment, the relative contents of β1-sheets, β2-sheets, random coils, and disulfide bonds of the OSPI increased while the surface hydrophobicity, absolute ζ-potential value and free sulfhydryl content decreased. Moreover, protein aggregates with larger particle sizes and poor solubility were formed. The emulsions prepared using the OSPI showed bridging flocculation and decreased protein adsorption and interfacial tension. After applying medium-power ultrasound (300 W, 400 W, and 500 W) treatments, the OSPI solubility increased and particle size decreased. The α-helix and β-turn contents, surface hydrophobicity and absolute ζ-potential value increased, the structure unfolded, and the disulfide bond content decreased. These changes improved the emulsification activity and emulsion state of the OSPI and increased the protein adsorption capacity and interfacial tension of the emulsion. However, after a high-power ultrasound (600 W) treatment, the OSPI showed a tendency to reaggregate, which had a certain negative effect on the emulsification activity and interfacial activity. The results showed that UT at an appropriate power could depolymerize OSPI and improve the emulsification and interfacial activity of soybean protein.

Achieving “Non-Foaming” Rhamnolipid Production and Productivity Rebounds of Pseudomonas aeruginosa under Weakly Acidic Fermentation

The rhamnolipid production of Pseudomonas aeruginosa has been impeded by its severe foaming; overcoming the bottleneck of foaming has become the most urgent requirement for rhamnolipid production in recent decades. In this study, we performed rhamnolipid fermentation under weakly acidic conditions to address this bottleneck. The results showed that the foaming behavior of rhamnolipid fermentation broths was pH-dependent with the foaming ability decreasing from 162.8% to 28.6% from pH 8 to 4. The “non-foaming” rhamnolipid fermentation can be realized at pH 5.5, but the biosynthesis of rhamnolipids was significantly inhibited. Further, rhamnolipid yield rebounded from 8.1 g/L to 15.4 g/L after ultraviolet and ethyl methanesulfonate compound mutagenesis. The mechanism study showed that the species changes of rhamnolipid homologs did not affect the foaming behavior of the fermentation but had a slight effect on the bioactivity of rhamnolipids. At pH 8.0 to 5.0, increased surface tension, decreased viscosity and zeta potential, and aggregation of rhamnolipid molecules contributed to the “non-foaming” rhamnolipid fermentation. This study provides a promising avenue for the “non-foaming” rhamnolipid fermentation and elucidates the mechanisms involved, facilitating the understanding of pH-associated foaming behavior and developing a more efficient strategy for achieving rhamnolipid production.

Research Status and Prospect for Vibration, Noise and Temperature Rise-Based Effect of Food Transport Pumps on the Characteristics of Liquid Foods

In the field of food processing, the processing of liquid foods has always played an important role. Liquid foods have high requirements for the processing environment and equipment. As the core equipment in liquid foods processing, food transport pumps are widely used in liquid foods production, processing and transportation. Most liquid foods are non-Newtonian and vulnerable to vibration, noise, and temperature rise produced by rotary motions of food transport pumps in operation, which can finally affect foods safety. Therefore, this review summarizes the impact of mechanical vibration, noise, and temperature rise on liquid food products, with the aim of ensuring food safety while designing a cleaner, safer and more reliable food transport pumps in the future.

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.

Influence of milk fat globule membrane and milk protein concentrate treated by ultrasound on the structural and emulsifying stability of mimicking human fat emulsions

The primary objective of the present study was to investigate the effectiveness of ultrasonic treatment time on the particle size, molecular weight, microstructure and solubility of milk fat globule membrane (rich in phospholipid, MPL) and milk protein concentrate (MPC). The mimicking human fat emulsions were prepared using modified proteins and compound vegetable oil and the structural, emulsifying properties and encapsulation efficiency of emulsions were evaluated. After ultrasonic treatment, the cavitation caused particle size decreased and structure change of both MPL and MPC, resulting in the enhancement of protein solubility. While, there was no significant change in molecular weight. Modified proteins by ultrasonic may cause a reduction in particle size and an improvement in emulsifying stability and encapsulation efficiency of emulsions. The optimal ultrasonic time to improve functional properties of MPL emulsion and MPC emulsion were 3 min and 6 min, respectively. The emulsifying stability of MPL emulsion was superior to MPC emulsion, which indicated that MPL is more suitable as membrane material to simulate human fat. Therefore, the obtained results can provide basis for quality control of infant formula.

Ultrasound-assisted extraction of protein from Bombay locusts and its impact on functional and antioxidative properties

Impact of ultrasound-assisted process (UAP) on yield, functional properties, antioxidant properties and molecular characteristics of protein extracted from Bombay locusts (BL) (Patanga succinta L.) was studied. Different conditions of UAP were implemented for different amplitudes (40-60%) and times (10-30 min) during aqueous extraction. Notably, UAP could enhance yield and protein recovery, compared with those from typical process (TP) (continuously stirred at 100 rpm at room temperature for 1 h). UAP conditions used governed the change of surface hydrophobicity and free α-amino content of BL. UAP could improve solubility of BL, especially at pH levels higher than 2. UAP had no significant (p > 0.05) detrimental effects on foaming capacity and stability of BL. Nevertheless, UAP, particularly at 50-60% amplitudes, affected the emulsion activity and stability of BL. UAP provided BL with high radical scavenging activities and good electron donating ability, especially that from 60% amplitude for 20 min (UAP-60/20). UAP-60/20 showed the impact on change of isoelectric point and molecular characteristic monitored by Fourier transform infrared (FTIR) of BL, compared to those from TP. In addition, BL was also an excellent source of both essential and nonessential amino acids. Therefore, UAP potentially enhanced BL extraction efficiency, resulting the BL with good functional and antioxidative properties.

Investigation of the consequences of ultrasound on the physicochemical, emulsification, and gelatinization characteristics of citric acid-treated whey protein isolate

The effect of ultrasound (US) pretreatment (0, 200, 400, 600, and 800 W) on the physicochemical, emulsification, and gelatinization characteristics of citric acid (CA)-treated whey protein isolate (WPI) was investigated. Size exclusion chromatography demonstrated that when compared with untreated WPI, US pretreatment promoted production of more molecular polymers in the CA-treated WPI. There was a reduction in particle size of CA-treated WPI with the increase of US power (0-800 W), whereas its free sulfhydryl content, surface hydrophobicity, and intrinsic fluorescence strength increased. Furthermore, compared with untreated WPI, emulsifying ability index and emulsifying stability index of CA-treated WPI were increased by 14.04% and 10.10%, respectively, at 800 W. Accordingly, US pretreatment promoted the gel formation of CA-treated WPI, and its gel hardness was increased by 28.0% with US power ranging from 0 to 800 W. Therefore, US and CA treatment can be considered as an effective way to improve the emulsifying and gelatinization characteristics of WPI.

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.

Ultrasound-assisted Maillard reaction of ovalbumin/xylose: The enhancement of functional properties and its mechanism

This study aims to optimize the ultrasound treatment conditions for enhancing the degree of glycation (DG) of ovalbumin (OVA)-xylose conjugates through Maillard reaction and investigate the correlation between DG and functional properties affected by structural changes. The structural and functional properties of classical heating OVA, glycated OVA, ultrasonic treated OVA, and ultrasound-assisted glycated OVA were investigated to explore the interaction mechanism of ultrasound treatment on foaming and emulsifying properties improvement. Results indicated that the ultrasound assistance increased free sulfhydryl content, surface hydrophobicity and particle size of OVA-xylose conjugates, and thus enhancing the surface properties, which were strongly linear correlated with DG under different glycation parameters (pH, xylose/OVA ratio, heating time). Additionally, circular dichroism spectroscopy analysis revealed that ultrasound promoted the conversion of α-helices to β-sheets and unfolded structures, which was consistent with the formation of short amyloid-like aggregates that observed by atomic force microscopy phenomenon. Overall, our study provides new insights into the effects of ultrasound treatment on Maillard-induced protein functional properties enhancement, which may be a new strategy to tune the DG and functionality of protein-saccharide grafts during ultrasound processing.

Effects of Pulsed Electric Fields and Ultrasound Processing on Proteins and Enzymes: A Review

There is increasing demand among consumers for food products free of chemical preservatives, minimally processed and have fresh-like natural flavors. To meet these growing demands, the industries and researchers are finding alternative processing methods, which involve nonthermal methods to obtain a quality product that meets the consumer demands and adheres to the food safety protocols. In the past two decades’ various research groups have developed a wide range of nonthermal processing methods, of which few have shown potential in replacing the traditional thermal processing systems. Among all the methods, ultrasonication (US) and pulsed electric field (PEF) seem to be the most effective in attaining desirable food products. Several researchers have shown that these methods significantly affect various major and minor nutritional components present in food, including proteins and enzymes. In this review, we are going to discuss the effect of nonthermal methods on proteins, including enzymes. This review comprises results from the latest studies conducted from all over the world, which would help the research community and industry investigate the future pathway for nonthermal processing methods, especially in preserving the nutritional safety and integrity of the food.

Effects of high and low frequency ultrasound on the production of volatile compounds in milk and milk products - a review

The effects of low and high frequency ultrasound on the production of volatile compounds along with their derivation and corresponding off-flavours in milk and milk products are discussed in this review. The review will simultaneously discuss possible mechanisms of applied ultrasound and their respective chemical and physical effects on milk components in relation to the production of volatile compounds. Ultrasound offers potential benefits in dairy applications over conventional heat treatment processes. Physical effects enhance the positive alteration of the physicochemical properties of milk proteins and fat. However, chemical effects propagated by free radical generation cause redox oxidations which in turn produce undesirable volatile compounds such as aldehydes, ketones, acids, esters, alcohols and sulphur, producing off-flavours. The extent of volatile compounds produced depends on ultrasonic processing conditions such as sonication time, temperature and frequency. Low frequency ultrasound limits free radical formation and results in few volatile compounds, while high ultrasonic frequency induces greater level of free radical formation. Furthermore, the compositional variations in terms of milk proteins and fat within the milk systems influence the production of volatile compounds. These factors could be controlled and optimized to reduce the production of undesirable volatiles, eliminate off-flavours, and promote the application of ultrasound technology in the dairy field.