The impact of ultrasound duration on the structure of β-lactoglobulin

Impact of bee pollen cell-wall disrupting techniques on the structural integrity, functional attributes, and nutritional quality of bee pollen protein isolates for food application

This study standardized the protein extraction protocol from bee pollen by disrupting the cell wall to obtain bee pollen protein isolates (BPPI) using different pre-treatments: ultrasonication (US-BPPI), pectinase (PE-BPPI), and a combination of ultrasonication and pectinase (US-PEBPPI). The extraction and precipitation pH variables were also optimized, with an extraction pH of 10.5 and precipitation pH of 4.5 identified as ideal based on protein yield and purity. Compared to untreated BPPI, US-PE-BPPI demonstrated significant enhancement in yield (70 %) and purity (20 %) alongside an increase in solubility (88 %), water and oil holding capacity (286 % and 225 %), and emulsifying activity index (223 m2/g). Ultrasonication and pectinase synergistically disrupted the cell wall, with ultrasonication applying shear forces and pectinase degrading polysaccharides. These dual treatments induced molecular modifications in the protein secondary structure, evident from reduced crystallinity and expended coil regions, which correlated with improved techno-functional properties. Furthermore, the nutritional analysis highlighted the benefits of US-PE-BPPI, with a 1.2-fold increase in essential and non-essential amino acids, a 1.27-fold rise in essential amino acid index, and significant improvements in biological value (1.31-fold) and nutritional index (1.5-fold). This study is the first to reveal how ultrasonication and pectinase synergistically enhance the nutritional and functional quality of BPPI.

Ultrasound-assisted modification to improve the red pepper seed protein isolate structural, functional, and antioxidant properties

The study aims to extract protein from red pepper seeds and analyze the effect of ultrasound (US) on red pepper seed protein isolates (RPSPI) at pH 7 and 9. Circular dichroism (CD) spectroscopy analyzed structural changes in RPSPI, revealing that the increase in US treatment duration from 5 to 20 min was associated with decreased β-turn and α-helix while improving the β-sheet and random coil content. It demonstrates that US treatment stimulated protein unfolding and significantly disrupted distinct types of H bonds in the RPSPI, especially those involved in forming β-turns and α-helix. US treatment significantly improved the free sulfhydryl groups, revealing modified tertiary protein structures. The dissociation of large RPSPI aggregates into smaller ones significantly reduced the average particle size in aqueous suspensions. Ultimately, these changes enabled US-treated RPSPI samples to exhibit increased water solubility, emulsifying activity index, emulsifying stability index, water holding capacity, oil holding capacity, foaming characteristic, and foaming stability at pH 7 and 9, with maximum improvement of 25 %, 49.4 %, 45.11 %, 65.1 %, 46.2 %, 71.1 %, and 81.8 %, respectively. US treatments significantly increased the DPPH, ABTS, and OH scavenging ability (%) of RPSPI at pH 9, with a maximum improvement of 58 %, 33 %, and 36 %, respectively. Moreover, the principal component analysis demonstrated that the structural changes correlated with its functional and antioxidant properties.

Stability and functionality of bovine lactoferrin powder after 9 years of storage

Bovine lactoferrin (bLF) is a multifunctional protein widely used in food industries. Most bLF products are delivered in a powder form; however, their stability remains unclear. Herein, freeze-dried bLF powders were stored at 4 °C and 40 % relative humidity (RH) for 9 years since 2016. After the long-term storage, their functional properties, including antibacterial ability, antioxidant ability and iron-binding ability, were determined and compared with those of eight commercial LF powders. The bLF powder stored for 9 years demonstrated comparable physicochemical and functional properties with those of commercial LF powders (e.g. >93 % water solubility, >100 mg/100 g iron-binding ability, and >1.7 logCFU/mL bacterial growth reduction against Salmonella enteritidis). The haemolysis test indicated that the bLF stored for 9 years exhibited good biocompatibility at a concentration of <5 mg/mL. Therefore, bLF powders can be stored for extremely long periods (>9 years) with minimal side effects. These findings can expand the utilisation of lactoferrin to many specific cases such as voyage and aerospace foods.

Fabrication of novel pullulan/carboxymethyl chitosan-based edible film incorporated with ultrasonically equipped aqueous zein/turmeric essential oil nanoemulsion for effective preservation of mango fruits

This study aimed to develop ultrasonically-assisted, alcohol-free, and noncorrosive aqueous zein/turmeric essential oil (TEO)-loaded nanoemulsions (NEs) to stimulate pullulan/carboxymethyl chitosan (P/CMCS)-based edible films for mango fruit preservation. The influence of innovative sonicated zein/TEO-based NEs (ZTNEs) as nanofillers on the physico-mechanical characteristics of the resulting P/CMCS edible films was investigated. A stable and well-dispersed ZTNE was achieved using 20 % zein with 10 min of ultrasound treatment, leading to a reduced droplet size (194.23 ± 0.41 nm) and high ζ-potential (-48.72 ± 0.74 mV). Furthermore, the homogeneity of the ZTNE dispersion, evaluated via confocal laser microscopy (CLSM) analysis, indicated that it can be uniformly incorporated into P/CMCS edible films. In addition, the incorporation of ZTNE into P/CMCS edible films improved barrier properties, mechanical strength, oxidative stability, and antimicrobial properties compared with P/CMCS edible films without ZTNE, possibly due to hydrogen bonding in the film matrix, as confirmed by scanning electron microscopy (SEM) micrographs as well as Fourier transform infrared spectroscopy and X-ray diffraction. Interestingly, the results indicated that P/CMCS/ZTNE/US 10 min and P/CMCS/ZTNE 4 % films demonstrated substantial antibacterial activity against Escherichia coli (11.54 ± 0.72 and 16.62 ± 1.13 mm, respectively) and Staphylococcus aureus (12.81 ± 1.03 and 14.13 ± 0.69 mm), respectively. Moreover, P/CMCS/ZTNE/US 10 min and P/CMCS/ZTNE 4 % films were found to be effective in mango preservation over a 12-day storage period at 25 °C ± 1 °C, as assessed by fruit firmness, weight loss, total soluble solid content, total phenolic content, lipoxygenase activity, and electronic nose analysis. Consequently, these findings indicate that P/CMCS/ZTNE edible films may function as an effective biodegradable packaging solution for fruit preservation within the food industry.

Ultrasound-assisted fermentation effectively alleviates the weakening of wheat gluten network caused by long-chain inulin and the underlying mechanism

The main objective of the article is to elucidate the effects of ultrasonic treatment with different ultrasonic power (0 W, 200 W, 250 W, 300 W, 400 W and 500 W) on the rheology, water distribution, sulfhydryl disulfide bond content, microstructure, and gluten properties of FXL (Long-chain inulin) dough. When the ultrasonic power is 300 W, the protein polymerization can be promoted, thus improving the gluten network. The mechanical action and cavitation induced by ultrasound changed the water distribution of FXL dough and promoted the transition from weakly bound water to tightly bound water. The T21 value (tightly bound water relaxation time) was shortened from 0.25 to 0.16 and the A21 (tightly bound water content) was reduced from 6.35 to 5.18, an improvement of 22.6 %, at a power of 300 W. Ultrasound decreased the enthalpy of FXL dough, and increased the particle size and potential of gluten protein. The introduction of ultrasound increased the content of β-sheets structure (40.85) at 250 W. The microstructure of the FXL dough revealed that ultrasonic treatment induced a continuous tight membrane-like gluten network, while the application of 500 W ultrasonic power resulted in the exposure and depression of starch particles.

Does Transglutaminase Crosslinking Reduce the Antibody Recognition Capacity of β-Lactoglobulin: An Analysis from Conformational Perspective

Food allergies are a global concern, with β-lactoglobulin (β-LG) in bovine milk being a major allergenic protein. This study investigated the effects of transglutaminase (TGase)-mediated crosslinking on the antibody recognition capacity (ARC) and structural properties of β-LG, with the aim of developing hypoallergenic dairy products. β-LG solutions were treated with TGase at varying concentrations (0, 5, 10, 15, and 20 U/g) and durations (0, 6, 18, 24, and 42 h), followed by analysis using electrophoresis, enzyme-linked immunosorbent assay (ELISA), and spectroscopy. The results demonstrated that treatment with TGase at 20 U/g significantly reduced the ARC and immunoglobulin E (IgE) binding capacity of β-LG to 90.0 ± 0.4% and 58.4 ± 1.0%, respectively, with the optimal ARC reduction observed after 6 h of treatment (86.7 ± 1.2%, p < 0.05). Although electrophoresis did not reveal significant crosslinking of β-LG, ultraviolet absorption, fluorescence intensity, and hydrophobicity all increased with prolonged crosslinking time, while sulfhydryl content fluctuated irregularly. These findings suggest that β-LG underwent varying degrees of structural modification, which led to the masking of antigenic epitopes during the early stages (0-24 h), followed by their re-exposure at the later stage (42 h). Overall, these results highlight the potential of TGase to reduce β-LG potential allergenicity, presenting a promising strategy for the development of hypoallergenic dairy products.

Impact of ultrasonic pretreatment on pumpkin seed protein: Effect on protease activities, protein structure, hydrolysis kinetics and functional properties

Adding value to food by-products, such as pumpkin seeds, is an important strategy for the complete utilization of plant foods and advancing sustainability goals. This study aimed to maximize the production of bioactive peptides from pumpkin seed protein (PSP) by combining ultrasonic (US) pretreatment (40 kHz, 23.8 W/L) with enzymatic hydrolysis. The PSP's structure after sonication and its effects on the commercial proteases (Brauzyn®, Flavourzyme®, Neutrase®) activity and degree of hydrolysis were studied. The hydrolysis consequences regarding solubility and antioxidant activity of the resulting peptides were also evaluated. Sonication of PSP increased enzymatic activity by up to 21.3 % for Brauzyn®, 24.8 % for Flavourzyme® and 19.2 % for Neutrase®. Consequently, there was an increase in the degree of hydrolysis (up to 89 %) using sonicated PSP, particularly at 60 min/40 °C. These effects can be attributed to ultrasound-induced protein conformation changes, including increased intrinsic fluorescence intensity (<22 %), shifts in UV spectra, and alterations in FTIR amide bands, especially a decrease in β-sheet content (<7.14 %). Additionally, ultrasonic pretreatment reduced particle size (<43.9 %) and polydispersity index (<58 %), enhancing enzyme accessibility by fragmenting protein aggregates, as observed via scanning electron microscopy. As a result, the peptides obtained from the hydrolysis of sonicated PSP exhibited higher protein solubility (12 % to 49 % at pH 6.0) and improved antioxidant activity (5.6 % to 77 %). Overall, sonication of PSP for 60 min at 40 °C followed by hydrolysis with Neutrase® proved to be the most effective strategy for producing highly soluble peptides with enhanced antioxidant properties, highlighting the potential of ultrasound as a valuable tool for optimizing bioactive peptide production. Based on these results, the developed process is ready for scale-up by the food industry, aiming to obtain protein hydrolysates with improved functional and/or nutritional properties from a low-cost raw material. In parallel, further researches can focus on the potential application of these hydrolysates as ingredients in bakery, meet or dairy products.

Contribution of ultrasound-assisted protein structural changes in marinated beef to the improved binding ability of spices and flavor enhancement

BACKGROUND

Marination is an important part of air-dried beef processing, and traditional methods are inefficient and produce inconsistent results. Ultrasound, as a novel technology, can be combined with traditional marination methods. The study aimed to investigate the improvement of beef flavor by ultrasound-assisted marination. At the same time, the potential relationship between the alteration of meat protein and flavor quality by ultrasound-assisted marinating was further investigated to enable better flavor modulation and research.

RESULTS

Headspace solid-phase microextraction-gas chromatography-mass spectrometry revealed that the spice flavor of beef was significantly enhanced by 500 W ultrasound-assisted marination. Meanwhile, the experimental results demonstrated that the ultrasound-assisted marination promoted the unfolding of beef myofibrillar protein structure, which increased the number of hydrophobic and hydrogen bonding sites, enhanced the electrostatic effect and improved the functional properties of the protein. Ultrasound-assisted marination significantly enhanced the binding ability of beef myofibrillar proteins to flavor compounds compared with conventional marination. An electronic nose confirmed that this resulted in a significant increase in the flavor of the marinated meat.

CONCLUSION

Ultrasound-assisted marination effectively enhanced the flavor of marinated meat, which was closely related to the development of protein conformation. The results of this study have important implications for the food industry and the role of protein unfolding processes in flavor modulation. In particular, the findings can be practically applied to improving meat flavor under ultrasound-assisted marination. © 2024 Society of Chemical Industry.

New insights into ultrasound-assisted noncovalent nanocomplexes of β-lactoglobulin and neochlorogenic acid/cryptochlorogenic acid and its potential application for curcumin loading

The cross-linking sites and structure of protein-polyphenol complexes are susceptible to the type, structure, weight of polyphenols under nonthermal process. The low bioavailability and poor gastrointestinal instability of curcumin (CUR) hampers its application. Hence, changes in binding mechanism, structural and functional properties between β-lactoglobulin (β-LG) with two different configurations of chlorogenic acids (neochlorogenic acids (3-CQA) and cryptochlorogenic acids (4-CQA) by non-covalent binding under ultrasonic treatment, and the potential capacity for loading CUR were researched. The binding affinity scores of β-LG-4CQA was -7.1 kcal/mol. It is higher than β-LG-3CQA (-6.8 kcal/mol), which implied that the interaction between β-LG and 4-CQA was stronger. Circular dichroism calculations showed that the sonicated complex of the β-LG and 4-CQA with a decreased content of α-helices by 5.4 %, β-sheets by 4.6 %, and an increased content of irregular curls by 8.4 % (p < 0.05). The result demonstrated ultrasound and the binding of β-LG to 3/4-CQA improved the hydrophilicity, thermal stability, and antioxidant property of β-LG. Furthermore, the embedding rate of CUR in the ultrasound-assisted β-LG-4-CQA complex could reach 71.56 %. Consistent with the structural characterization results, the CUR release rate of ULG-4-CQA + CUR complex reached 17.36 % in simulated intestinal digestion, which was 8.09 % higher than free CUR. Indicating that after embedding with protein-polyphenol complexes, the stability and bioaccessibility of CUR was improved. This study reveals the potential application of ultrasound-assisted protein-polyphenol complexes for loading CUR.

Human milk whey proteins: Constituents, influencing factors, detection methods, and comparative analysis with other sources

Whey proteins, the most abundant proteins in human milk (HM), play a vital role in the growth and development of infants. This review first elaborates on the main components of HM whey proteins, including various proteins with specific functions, and details the functions of these proteins in terms of infant nutrition, immunity, as well as growth and development. Secondly, it analyzes factors that affect HM whey proteins, such as maternal differences, dietary habits, and geographical differences. Thirdly, it discusses detection methods for HM whey proteins, covering the principles, advantages, and limitations of different technical means. Finally, it compares whey proteins from different milk sources, highlighting their differences in composition, function, and characteristics. This review aims to comprehensively present the current research status of HM whey protein, provide a scientific basis for maternal and infant health, and contribute to optimizing infant feeding strategies and the research and development of related products.

Impact of ultrasonic and heat treatments on the physicochemical properties and rennet-induced coagulation characteristics of milk from various species

This study investigates the effects of heat and ultrasonic treatments on the physicochemical parameters and rennet-induced coagulation properties of milk from a variety of species, including cow, goat, buffalo, and donkey. Milk samples were subjected to heat treatments at different temperatures (65 °C, 80 °C, 90 °C, 100 °C) and ultrasonic treatment at varying power levels (200 W, 400 W, 600 W, 800 W, 1000 W). The results revealed that changes in turbidity, particle size, zeta potential, secondary structure, and surface hydrophobicity were altered by both ultrasonic and heat treatments, as well as the kind of milk. Ultrasonic treatment of cow milk decreased α-helix content while increasing β-turn content. Under similar ultrasonic treatment, goat milk showed a considerable increase in β-sheet content, whereas β-turn and random coil contents decreased compared to control samples. Notably, the water-holding capacity of gels formed from all four types of milk increased significantly with the intensity of ultrasonic and heat treatments. The hardness of buffalo milk gels increased significantly after ultrasonic and thermal treatments, ranging from 63 °C for 30 min to 90 °C for 15 min, but the hardness of cow and goat milk gels increased in varying degrees compared to their control samples. Furthermore, gels from cow and goat milk had higher storage modulus (G') and loss modulus (G'') than those from buffalo and donkey milk, and changes in G' and G'' from the examined milk were altered by ultrasonic and heat treatments. These findings offer important insights into refining milk processing procedures to improve dairy product quality and usefulness.

Effects of ultrasound pretreatment on the structure, IgE binding capacity, functional properties and bioactivity of whey protein hydrolysates via multispectroscopy and peptidomics revealed

Whey protein is an important food ingredient, but it is also considered a major food allergen. The aim of this study was to investigate the effect of ultrasound pretreatment on the structure, IgE binding capacity, functional properties and biological activity of whey protein isolate (WPI) hydrolysates (WPH), including WPI hydrolyzed by a combination of enzymes from Bromelain and ProteAXH (BA-WPI) and WPI hydrolyzed by a combination of enzymes from Papain W-40 and ProteAXH (PA-WPI). The IgE binding capacity of BA-WPI and PA-WPI was reduced to 40.28% and 30.17%, respectively, due to disruption/exposure/shielding of conformational and linear epitopes. The IgE binding capacity of sonicated WPI was increased, but ultrasound pretreatment further reduced the IgE binding capacity of the hydrolysates to 32.89% and 28.04%. This is due to the fact that ultrasound pretreatment leads to conformational changes including increased α-helix and β-sheet structure, exposure of aromatic amino acids, surface hydrophobicity, and increased sulfhydryl content, which increases the accessibility of allergenic epitopes to WPI by the enzyme. Multispectral and LC-MS/MS results further indicated that ultrasound pretreatment altered the conformational and primary structural changes of the hydrolysates. The thermograms showed that ultrasound pretreatment mainly altered the epitope spectra of β-lactoglobulin hydrolysates, while it had less effect on the epitope spectra of α-lactalbumin hydrolysates. Additionally, ultrasound pretreatment significantly improved the foaming properties, antioxidant activity, and α-glucosidase inhibition of the hydrolysates without impairing the solubility and emulsification properties of the hydrolysates. Therefore, ultrasound pretreatment is a feasible method to reduce the allergenicity of WPH and to improve their functional properties and bioactivity. Notably, ultrasonic pretreatment improved the effectiveness and efficiency of WPI hydrolysis, which is a feasible method to produce high-quality protein feedstock in a green, efficient, and economical way.

Preparation and functional characterization of pullulan-sodium alginate composite film enhanced with ultrasound-assisted clove essential oil Nanoemulsions for effective preservation of cherries and mushrooms

Clove essential oil (CEO) exhibited potent antibacterial efficacy and are obtained from Eugenia caryophyllata tree flower buds. Herein, CEO nanoemulsions were prepared using various concentrations of casein protein treated with ultrasound for different time interval. The study demonstrated that CEO nanoemulsions with 5% casein protein subjected to ultrasound for 10 min displayed the most minimal particle size. The pullulan‑sodium alginate film incorporated with nanoemulsions treated with ultrasound exhibited enhanced physico-mechanical characteristics. Based on the structural analysis, the application of ultrasonic treatment improved intermolecular compatibility and organized molecular structure by strengthening hydrogen bonds. Furthermore, the composite film displayed remarkable efficacy against E. coli and S. aureus as well as longer retention of essential oils. The use of the developed films to protect cherry fruits and mushrooms produced promising results, emphasizing their potential in food packaging applications.

Optimization and Preparation of Ultrasound-Treated Whey Protein Isolate Pickering Emulsions

This study aimed to create Pickering emulsions with varying oil fractions and assess the impact of ultrasonic treatment on the properties of Whey Protein Isolates (WPIs). At 640 W for 30 min, ultrasound reduced WPI aggregate size, raised zeta potential, and improved foaming, emulsifying, and water-holding capacities. FTIR analysis showed structural changes, while fluorescence and hydrophobicity increased, indicating tertiary structure alterations. This suggests that sonication efficiently modifies WPI functionality. Under ideal conditions, φ = 80 emulsions were most stable, with no foaming or phase separation. Laser scanning revealed well-organized emulsions at φ = 80. This study provides a reference for modifying and utilizing WPI.

Yeast Proteins: Proteomics, Extraction, Modification, Functional Characterization, and Structure: A Review

Proteins are essential for human tissues and organs, and they require adequate intake for normal physiological functions. With a growing global population, protein demand rises annually. Traditional animal and plant protein sources rely heavily on land and water, making it difficult to meet the increasing demand. The high protein content of yeast and the complete range of amino acids in yeast proteins make it a high-quality source of supplemental protein. Screening of high-protein yeast strains using proteomics is essential to increase the value of yeast protein resources and to promote the yeast protein industry. However, current yeast extraction methods are mainly alkaline solubilization and acid precipitation; therefore, it is necessary to develop more efficient and environmentally friendly techniques. In addition, the functional properties of yeast proteins limit their application in the food industry. To improve these properties, methods must be selected to modify the secondary and tertiary structures of yeast proteins. This paper explores how proteomic analysis can be used to identify nutrient-rich yeast strains, compares the process of preparing yeast proteins, and investigates how modification methods affect the function and structure of yeast proteins. It provides a theoretical basis for solving the problem of inadequate protein intake in China and explores future prospects.

Ultrasound-mediated host-guest self-assembly between different dietary fatty acids and sodium caseinate and their complexes improving the water dispersibility, stability, and bioaccessibility of quercetin

Quercetin (QUE) sufferred from poor processing adaptability and absorbability, hindering its application as a dietary supplement in the food industry. In this study, fatty acids (FAs)-sodium caseinate (NaCas) ligand complexes carriers were fabricated to improve the aqueous dispersibility, storage/thermal stability, and bioaccessibility of QUE using an ultrasound method. The results indicated that all six selected common dietary FAs formed stable hydrophilic complexes with NaCas and the FAs-NaCas complexes achieved an encapsulation efficiency greater than 90 % for QUE. Furthermore, the introduction of FAs enhanced the binding affinity between NaCas and QUE, but did not change the binding mode (static bursting) and types of intermolecular forces (mainly hydrogen bonding). In addition, a distinct improvement was discovered in the storage stability (>2.37-fold), thermal processing stability (>32.54 %), and bioaccessibility (>2.37-fold) of QUE. Therefore, the FAs-NaCas ligand complexes could effectively protect QUE to minimize degradation as fat-soluble polyphenol delivery vehicles.

Sonication-mediated modulation of macronutrient structure and digestibility in chickpea

Ultrasound processing is an emerging green technology that has the potential for wider application in the food processing industry. While the effects of ultrasonication on isolated macromolecules such as protein and starch have been reported, the effects of physical barriers on sonication on these macro-molecules, for example inside whole seed, tissue or cotyledon cells, have mostly been overlooked. Intact chickpea cells were subjected to sonication with different ultrasound processing times, and the effects of sonication on the starch and protein structure and digestibility were studied. The digestibility of these macronutrients significantly increased with the extension of processing time, which, however was not due to the molecular degradation of starch or protein but related to damage to cell wall macro-structure with increasing sonication time, leading to enhanced enzyme accessibility. Through this study, it is demonstrated that ultrasound processing has least effect on whole food structure, for example, whole seeds but can modulate the nutrient bioavailability without changing the properties of the macronutrients in seed fractions e.g. intact cells, offering new scientific knowledge on effect of ultrasound in whole foods at various length scales.

Exploring the binding mechanisms of thermally and ultrasonically induced molten globule-like β-lactoglobulin with heptanal as revealed by multi-spectroscopic techniques and molecular simulation

This work employed the model protein β-lactoglobulin (BLG) to investigate the contribution of microstructural changes to regulating the interaction patterns between protein and flavor compounds through employing computer simulation and multi-spectroscopic techniques. The formation of molten globule (MG) state-like protein during the conformational evolution of BLG, in response to ultrasonic (UC) and heat (HT) treatments, was revealed through multi-spectroscopic characterization. Differential MG structures were distinguished by variations in surface hydrophobicity and the microenvironment of tryptophan residues. Fluorescence quenching measurements indicated that the formation of MG enhanced the binding affinity of heptanal to protein. LC-MS/MS and NMR revealed the covalent bonding between heptanal and BLG formed by Michael addition and Schiff-base reactions, and MG-like BLG exhibited fewer chemical shift residues. Molecular docking and molecular dynamics simulation confirmed the synergistic involvement of hydrophobic interactions and hydrogen bonds in shaping BLG-heptanal complexes thus promoting the stability of BLG structures. These findings indicated that the production of BLG-heptanal complexes was driven synergistically by non-covalent and covalent bonds, and their interaction processes were influenced by processes-induced formation of MG potentially tuning the release and retention behaviors of flavor compounds.

Physico-chemical, functional, and structural properties of un-defatted, cold and hot defatted yellow lupin protein isolates

This study investigates the structure, physico-chemical and functional properties of yellow lupin isolate protein (YLPI) obtained by different processes (conventional wet and purely aqueous fractionation) from un-defatted (YLPIU), and hot (YLPIHD) and cold (YLPICD) defatted flour. The defatting process modified the physical, structural and functional characteristics of lupin protein isolates. Indeed, a decrease of α-helix, free sulfhydryl groups amount and an increase of disulfide bond levels were observed for defatted samples, improving their emulsifying stability. The defatting process exposes the hydrophobic groups present within the YLPI, which increases total sulfhydryl content and protein surface hydrophobicity. Hot and cold defatting induced a decrease in turbidity, water-holding capacity, oil adsorption capacity, tapped and poured bulk densities. In addition, the defatting process changed the particle size of protein isolates that induced changes in their viscosity. Tryptophan spectra and protein surface hydrophobicity indicated that YLPICD and YLPIHD underwent structural conformational change during the defatting process.

Study on stabilized mechanism of high internal phase Pickering emulsions based on commercial yeast proteins: Modulating the characteristics of Pickering particle via sonication

The primary significance of this work is that the commercial yeast proteins particles were successfully used to characterize the high internal phase Pickering emulsions (HIPPEs). The different sonication time (0,3,7,11,15 min) was used to modulate the structure and interface characteristics of yeast proteins (YPs) that as Pickering particles. Immediately afterward, the influence of YPs particles prepared at different sonication time on the rheological behavior and coalescence mechanism of HIPPEs was investigated. The results indicate that the YPs sonicated for 7 min exhibited a more relaxed molecular structures and conformation, the smallest particle size, the highest H0 and optimal amphiphilicity (the three-phase contact (θ) was 88.91°). The transition from extended to compact conformations of YPs occurred when the sonication time exceeded 7 min, resulting in an augmentation of size of YPs particles, a reduction in surface hydrophobicity (H0), and an elevation in hydrophilicity. The HIPPEs stabilized by YPs particles sonicated for 7 min exhibited the highest adsorption interface protein percentage and a more homogeneous three-dimensional (3D) protein network, resulting in the smallest droplet size and the highest storage (G'). The HIPPEs sample that stabilized by YPs particles sonicated for 15 min showed the lowest adsorption protein percentage. This caused a reduction in the thickness of its interface protein layer and an enlargement in the droplet diameter (D [3,2]). It was prone to droplet coalescence according to the equation used to evaluate the coalescence probability of droplets (Eq (2)). And the non-adsorbed YPs particles form larger aggregation structures in the continuous phase and act as "structural agents" in 3D protein network. Therefore, mechanistically, the interface protein layer formed by YPs particles sonicated 7 min contributed more to HIPPEs stability. Whereas the "structural agents" contributed more to HIPPEs stability when the sonication time exceeded 7 min. The present results shed important new light on the application of commercial YPs in the functional food fields, acting as an available and effective alternative protein.

Effect of ultrasonic frequency on the structural and functional properties of pea protein isolation

BACKGROUND

Pea protein, as a by-product of peas (Pisum sativum L.), is rich in a variety of essential amino acids that can meet the body's protein needs and is a valuable source of protein. Since the function of pea protein is closely related to its structure, pea protein has been subjected to different modifications in recent years to improve its application in food and to develop new products.

RESULTS

The effects of sonication frequency (primary and secondary time) on pea protein isolate's (PPI's) structural and functional properties were investigated. Sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that different sonication frequencies at the same power (600 W) treatment had no effect on PPI's molecular weight. Fourier-transform infrared spectroscopy revealed that treatment at different sonication frequencies caused secondary structural changes in PPI. The particle size distribution, foaming, stability, surface hydrophobicity, emulsification, and oxidation resistance of PPI were improved after primary and secondary sonication, but secondary sonication was not more effective than primary sonication for an extended period of time.

CONCLUSION

Overall, ultrasound is able to improve the structural and functional properties of pea proteins within a suitable range. It provides a theoretical basis for elucidating the modification of the structure and function of plant proteins by ultrasound and lays the foundation for the development of plant proteins in food applications as well as development. © 2023 Society of Chemical Industry.

Analysis of non-covalent interaction between β-lactoglobulin and hyaluronic acid under ultrasound-assisted treatment: Conformational structures and interfacial properties

Hyaluronic acid (HA) used as a food ingredient is gaining acceptance and popularity. However, the studies available for the effect of HA concentrations on the properties of β-lactoglobulin (β-LG) were limited. In this study, we investigated that the molecular characterization and functional properties of the complex formed by the non-covalent binding of β-LG and HA, as well as the ultrasound-assisted treatment at acidic pH. The optimal pH and ratio of β-LG/HA were set as 7 and 4:1, respectively. The fluorescence spectroscopy, circular dichroism spectroscopy, and molecular docking results revealed that the addition of HA and ultrasound induced a decrease in random coil and α-helix and an increase in β-sheet contents in β-LG. By the complexation with HA, the thermal stability, freezing stability, and antioxidant properties of β-LG were all improved under ultrasound treatment. The results of the present study can be useful for the modulation of HA based biopolymer complexes and the exploitation as encapsulating or structuring agents in food industry.

Improvement of physicochemical properties, microstructure and stability of lotus root starch/xanthan gum stabilized emulsion by multi-frequency power ultrasound

Multi-frequency power ultrasound was applied as an environmentally friendly technique to control the nanoparticles (LS/XG-NPs) embedded with lotus root starch/xanthan gum, with the aim of enhancing the stability of Pickering emulsions. The present investigation was centered on evaluating the impact of ultrasound technology on various aspects of the emulsions, encompassing their mean particle size, particle size distribution, zeta potential, microstructure, rheological characteristics, and environmental stability. The findings of this study indicate that ultrasonic treatment enhanced the adsorption of LS/XG-NP onto oil droplets surface, resulting in a reduction in their size. Additionally, ultrasonic treatment decreased the viscosity and Brownian motion rate of the emulsion stabilized by LS/XG-NP, leading to increased fluidity. Furthermore, the emulsion's thermal stability and resistance to environmental oxidation were significantly enhanced through ultrasonic treatment. The Pickering emulsions that were prepared using ultrasound demonstrated excellent resistance to acid, alkali (pH 2-8) and salt ions (50-300 mM NaCl) for a period of 30 days during storage. It was worth anticipating that ultrasound-assisted LS/XG-NPs could efficiently retard the volatilization of fishy odor components within fish oil. Taken together, the present research has evinced the efficacy of ultrasound in enhancing the stability of Pickering emulsions coated with LS/XG-NPs. These findings offer significant novel insights into the advancement of ultrasound-assisted Pickering emulsions that are stabilized with starch-based or biopolymeric materials.

Effect of high-intensity ultrasound on the structural and functional properties of proteins in housefly larvae (Musca demestica)

Insect protein has gradually attracted wide attention from the international research community as a promising source of high-quality protein that can replace traditional protein sources. The larvae of the housefly, a prevalent and widespread species, contain high levels of protein with beneficial properties, namely, anti-fatigue, anti-radiation, and anti-aging functions, as well as liver protection and immunity enhancement. This work thoroughly examined the impact of high-intensity ultrasound (HIUS) on the structural and functional characteristics of housefly larval concentrate protein (HLCP). HLCP samples were sonicated for 20 min at a frequency of 20 kHz with varying energies (0, 100, 200, 300, 400, and 500 W). The findings demonstrated that sonication considerably altered the secondary and tertiary structures of HLCP but had no effect on molecular weight. With an increase in ultrasonic power, HLCP's particle size shrank, more hydrophobic groups were exposed, more free sulfhydryl groups were present, the solution's stability improved, and HLCP's solubility rose. In addition, HLCP's emulsification and foaming abilities were improved by HIUS treatment. It is anticipated that this study's findings will offer fresh insights into the implementation of HLCP in the food sector.

Characterization of Nano-SiO2/Zein Film Prepared Using Ultrasonic Treatment and the Ability of the Prepared Film to Resist Different Storage Environments

This study has developed, ultrasound-assisted, a novel food packaging film (U-zein/SiO2) for food packaging applications. Incorporating an optimal concentration of 18 mg/mL of nano-SiO2 and subjecting the film to 10 min of ultrasonic treatment resulted in a remarkable increase of 32.89% in elongation at break and 55.86% in tensile strength. In addition, the incorporation of nano-SiO2 effectively reduces the water content and solubility of the composite film, resulting in improved water/oxygen barrier properties. These physiochemical properties were further improved with the application of ultrasound. The analysis of attenuated total reflectance-Fourier transform infrared, X-ray diffraction, differential scanning calorimetry, and scanning electronic microscope demonstrated that the ultrasound treatment improved the hydrogen bonds, improved thermal stability, molecular arrangement, structure stability, and intermolecular compatibility of the composite film, resulting in enhanced physio-mechanical properties of the film. In addition, the ultrasound treatment led to a smoother film surface and reduced the pores on the film's cross-section. Moreover, the U-zein/SiO2 film exhibited excellent mechanical and water/oxygen barrier properties in different storage environments over a period of 30 days. These results offer sound theoretical support for the practical application of the prepared preservative film.

Effect of high-intensity ultrasonic time on structural, mechanical, and physicochemical properties of β-conglycinin (7S)- Transglutaminase (TGase) composite edible films

The β-conglycinin (7S) was pre-treated with high-intensity ultrasonic (HIU) and subsequently formed into composite edible films with the transglutaminase (TGase) method. Effects of HIU pretreatment time (0, 5, 10, 15, and 20 min) on the conformation of 7S and structural and application properties of 7S-TGase films were evaluated. The analysis of 7S conformation results revealed that HIU pretreatment for 0-10 min significantly dissociated the 7S, exposed internal hydrophobic groups of protein, increased its intermolecular hydrogen bonds, and altered the protein secondary and tertiary structure. The structural properties of films were evaluated by SEM, XRD, and ATR-FTIR. SEM showed that HIU reduced film wrinkles and cracks and improved unevenness. XRD and ATR-FTIR indicated that the film obtained an enlarged crystallinity, and the amide I and amide II regions of films were peak-shifted which is usually associated with the formation of covalent bonds. Notably, analysis of intermolecular force showed that HIU facilitated the formation of hydrogen bonds, hydrophobic interactions, and ε-(γ-glutamyl) lysine bonds in 7S-TGase films. The above structural changes in 7S and films were beneficial for the application properties of films. Results indicated that 10 min HIU pretreatment effectively improved the mechanical properties and water resistance, reduced water vapor permeability and oxygen permeability, and decreased the opacity of 7S-TGase films. However, the color of the film was not affected by the HIU, with an overall bright and yellowish color.

Hemp seed protein and chlorogenic acid complex: Effect of ultrasound modification on its structure and functional properties

In this study, the effects of ultrasound and chlorogenic acid (CA) on the structural and functional properties of hemp seed protein (HSP) was investigated. Compared with natural HSP, the UV-vis spectra intensity of ultrasound-treated HSP (UHSP) and UHSP-CA increased, the fluorescence spectra intensity decreased with a red shift in the maximum intensity peak. The results showed that ultrasound modification and complexation with CA unfolded the structure of HSP exposing its internal groups. Fluorescence quenching analysis showed that the best binding between UHSP and CA (binding constant 2.94 × 10² L/mol) was achieved at 450 W for 15 min of ultrasound treatment. In addition, the same ultrasound conditions minimized the particle size and surface roughness of UHSP and UHSP-CA. The solubility of UHSP and UHSP-CA increased by 23.3 and 38.7 %, the emulsifying activity index increased by 16.9 and 16.2 %, and the emulsion stability index increased by 20.9 and 20.8 %, respectively. These results indicated that appropriate ultrasound treatment and complexation with CA can significantly modify the structural and functional properties of HSP, improving its application value in the food field.

Effect of high intensity ultrasonic treatment on structural, rheological, and gelling properties of potato protein isolate and its co-gelation properties with egg white protein

The study aimed to investigate the effect of high intensity ultrasonic (HIU) treatment at different times (0, 10, 20, and 30 min) on the structure and gel properties of water-soluble potato protein isolate (WPPI) and to further investigate the improvement of gel properties of ultrasonicated WPPI (UWPPI) by the addition of egg white protein (EWP). HIU reduced the particle size of WPPI, whose structure became loose and disordered, which improved gelling properties of UWPPI. Fourier transform infrared results indicated that α-helix content decreased, whereas the proportion of irregular curl increased with the increase in ultrasonication time (0-20 min), indicating that the initially ordered structure of UWPPI became disordered. After HIU treatment, the free sulfhydryl groups of UWPPI and surface hydrophobicity decreased and fluorescence intensity increased. These results demonstrated that the HIU loosened the structure of UWPPI, exposing more chromogenic groups while embedding more hydrophilic groups. After thermal induction, UWPPI gel hardness increased and exhibited excellent water holding capacity. After the addition of EWP, rheological properties stabilized, and the hardness of UWPPI-EWP gels increased significantly, forming internally structured protein gels with a tightly ordered structure and increased brightness. Thus, HIU changed the structure and gelling properties of WPPI, and the addition of EWP further enhanced the performance of hybrid protein gels. PRACTICAL APPLICATION: High intensity ultrasonic changed the structure of water-soluble potato protein isolate (WPPI) and improved the properties of WPPI gels. The addition of egg white protein significantly improved the quality of mixed protein gels which showed great potential industrial value.

Towards understanding the interaction between ultrasound-pretreated β-lactoglobulin monomer with resveratrol

Increasingly, studies are using ultrasound to elevate the functional properties of proteins, so the interaction between phenolic compounds and proteins induced by ultrasound needs to be further understood. β-Lactoglobulin (β-LG) at pH 8.1, which exists mainly as monomers, was ultrasound treated at 20 kHz ultrasonic intensity and 30% amplitude for 0-5 min and subsequently interacted with resveratrol. Fluorescence data showed that ultrasound pretreatment improved binding constant (K_a ) from (1.62 ± 0.45) × 10⁵ to (9.43 ± 0.55) × 10⁵  M^-1 and binding number from 1.13 ± 0.09 to 1.28 ± 0.11 in a static quenching mode. Fluorescence resonance energy transfer (FRET) analysis indicated that resveratrol bound to the surface hydrophobic pocket of native and treated proteins with no obvious changes in energy transfer efficiency (E) and Föster's distance (r). Thermodynamic parameters indicated that ultrasonication shifted the main driving force from the hydrophobic force for native and 1-min treated β-LG to van der Waals forces and hydrogen bonding for both 3-min and 5-min treated proteins. Ultrasonication and resveratrol addition generated significant differences in surface hydrophobicity and the surface charge of the protein (P < 0.05), whereas they had little influence on the secondary structure of β-LG. Compared with the native β-LG/resveratrol complex, ultrasound-treated protein complexes showed significantly stronger 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging capacity (P < 0.05), and kept relatively stable after 180-min irradiation. Data provided by this study can lead to a better comprehension of the structure and molecular events occurring during the complexing process between an ultrasound-pretreated protein with polyphenol.

Sonochemical effects on fabrication, characterization and antioxidant activities of β-lactoglobulin-chlorogenic acid conjugates

The β-lactoglobulin-chlorogenic acid (LG-CA) conjugate was explored to be formed through ultrasonication, redox-pair method and their combination, the ultrasonication used a probe ultrasonic machine with a 6 mm probe at 270 W, and the frequency was 20-25 kHz. The formation of the conjugate was confirmed by SDS-PAGE with a larger molecular weight. Besides, Fourier infrared spectroscopy (FTIR) and Circular dichroism (CD) indicated changes in the secondary structure of the LG-CA conjugate. The α-helix and β-sheet contents of LG decreased and the unordered content increased significantly after the formation of covalent complexes. In addition, both the ultrasonic treatment and its combination with redox-pair method could significantly improve the antioxidant properties of LG. The former increased to 23.16 μmol Trolox/g sample, the latter 82-106 μmol Trolox/g sample. Therefore, ultrasonication could be used both individually and in combination with the redox-pair method to produce LG-CA conjugates with stronger antioxidant activities.

Ultrasound-assisted development and characterization of novel polyphenol-loaded pullulan/trehalose composite films for fruit preservation

A novel food packaging film was developed by incorporating a tea polyphenols-loaded pullulan/trehalose (TP@Pul/Tre) into a composite film with ultrasound-assisted treatment of dual-frequency (20/35 kHz, 40 W/L) for 15 min to assess the physicochemical and mechanical properties of a composite film. The optimized ultrasound-assisted significantly increases elongation at break, tensile strength, and improves the composite film's UV/water/oxygen barrier properties. Structure analysis using attenuated total reflectance-Fourier transform infrared, X-ray diffraction and thermal stability revealed that these improvements were achieved through ultrasound-enhanced H-bonds, more ordered molecular arrangements, and good intermolecular compatibility. Besides, the ultrasound-assisted TP@Pul/Tre film has proven to have good antibacterial performance against Escherichia coli and Staphylococcus aureus, with approximately 100 % lethality at 4 h and 8 h, respectively. Moreover, the ultrasound-assisted TP@Pul/Tre film effectively delayed moisture loss, oxidative browning, decay, and deterioration in fresh-cut apples and pears, thereby extending their shelf life. Thus, ultrasound has proved to be an effective tool for improving the quality of food packaging films, with a wide range of applications.

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.

Alteration of the allergenicity of cow's milk proteins using different food processing modifications

Milk is an essential source of protein for infants and young children. At the same time, cow's milk is also one of the most common allergenic foods causing food allergies in children. Recently, cow's milk allergy (CMA) has become a common public health issue worldwide. Modern food processing technologies have been developed to reduce the allergenicity of milk proteins and improve the quality of life of patients with CMA. In this review, we summarize the main allergens in cow's milk, and introduce the recent findings on CMA responses. Moreover, the reduced effects and underlying mechanisms of different food processing techniques (such as heating, high pressure, γ-ray irradiation, ultrasound irradiation, hydrolysis, glycosylation, etc.) on the allergenicity of cow's milk proteins, and the application of processed cow's milk in clinical studies, are discussed. In addition, we describe the changes of nutritional value in cow's milk treated by different food processing technologies. This review provides an in-depth understanding of the allergenicity reduction of cow's milk proteins by various food processing techniques.

Effects of ultrasonic treatment on ovomucin: Structure, functional properties and bioactivity

The effects of ultrasonic treatment on the structure, functional properties and bioactivity of Ovomucin (OVM) were investigated in this study. Ultrasonic treatment could significantly enhance OVM solubility without destroying protein molecules. The secondary structure changes, including β-sheet reduction and random coil increase, indicate more disorder in OVM structure. After ultrasonic treatment, the OVM molecule was unfolded partially, resulting in the exposure of hydrophobic regions. The changes in OVM molecules led to an increase in intrinsic fluorescence and surface hydrophobicity. By detecting the particle size of protein solution, it was confirmed that ultrasonic treatment disassembled the OVM aggregations causing a smaller particle size. Field emission scanning electron microscopy (FE-SEM) images showed that ultrasonic cavitation significantly reduced the tendency of OVM to form stacked lamellar structure. Those changes in structure resulted in the improvement of foaming, emulsification and antioxidant capacity of OVM. Meanwhile, the detection results of ELISA showed that ultrasonic treatment did not change the biological activity of OVM. These results suggested that the relatively gentle ultrasound treatment could be utilized as a potential approach to modify OVM for property improvement.

Modifying the physicochemical properties, solubility and foaming capacity of milk proteins by ultrasound-assisted alkaline pH-shifting treatment

This study investigated the effects of different treatment of alkaline pH-shifting on milk protein concentrate (MPC), micellar casein concentrate (MCC) and whey protein isolate (WPI) assisted by the same ultrasound conditions, including changes in the physicochemical properties, solubility and foaming capacity. The solubility of milk proteins had a significant increase with gradual enhancement of ultrasound-assisted alkaline pH-shifting (p < 0.05), especially for MCC up to 99.50 %. Also, treatment made a significant decline in the particle size of MPC and MCC, as well as the turbidity of the proteins (p < 0.05). The foaming capacity of MPC, MCC, and WPI was all improved, especially at pH 11, and at this pH, the milk protein also showed the highest surface hydrophobicity. The best foaming capacity at pH 11 was the result of the combined effect of particle size, potential, protein conformation, solubility, and surface hydrophobicity. In conclusion, ultrasound-assisted pH-shifting treatment was found to be effective in improving the physicochemical properties and solubility and foaming capacity of milk proteins, especially MCC, with promising application prospect in food industry.

Influence of Farming System and Forecrops of Spring Wheat on Protein Content in the Grain and the Physicochemical Properties of Unsonicated and Sonicated Gluten

The potential for enhancing the spring wheat protein content by different cultivation strategies was explored. The influence of ultrasound on the surface and rheological properties of wheat-gluten was also studied. Spring wheat was cultivated over the period of 2018-2020 using two farming systems (conventional and organic) and five forecrops (sugar beet, spring barley, red clover, winter wheat, or oat). The obtained gluten was sonicated using the ultrasonic scrubber. For all organically grown wheat, the protein content was higher than for the conventional one. There was no correlation between the rheological properties of gluten and the protein content in the grain. Gluten derived from organically grown wheat was more elastic than those derived from the conventional one. Sonication enhanced the elasticity of gluten. The sonication effect was influenced by the forecrops. The most elastic gluten after sonication was found for organic barley and sugar beet. The lowest values of tan (delta) were noted for conventional wheat and conventional oat. Cultivation in the monoculture gave gluten with a smaller susceptibility to increase elasticity after sonic treatment. Sonication promoted the cross-linking of protein molecules and induced a more hydrophobic character, which was confirmed by an increment in contact angles (CAs). Most of the organically grown wheat samples showed a lower CA than the conventional ones, which indicated a less hydrophobic character. The gluten surface became rougher with the sonication, regardless of the farming system and applied forecrops. Sonication treatment of gluten proteins rearranged the intermolecular linkages, especially disulfide and hydrophobic bonds, leading to changes in their surface morphology.

Effect of pulsed electric field on soybean isoflavone glycosides hydrolysis by β-glucosidase: Investigation on enzyme characteristics and assisted reaction

This work aimed to investigate how pulsed electric field (PEF) technology as an alternative to enhance the enzymatic hydrolysis of soybean isoflavone glycosides (SIG). To achieve it, the effect of PEF treatment on the activity, kinetics, thermodynamics and structure of β-glucosidase (β-GLU) were evaluated. The parameters for PEF-assisted hydrolysis of soybean isoflavone glycosides were optimized by response surface methodology. The results showed that PEF treatment increased the relative activity and catalytic efficiency of β-GLU with moderate electric field intensity. Furthermore, PEF treatment induced the secondary and tertiary structural change of β-GLU, the α-helix content increased by 4.23% and the β-fold content decreased by 3.70%. The optimum conditions for PEF treatment were established as the highest yield of isoflavone aglycones achieved 94.58%. Therefore, these results indicated that PEF treatment could be used as an efficient process to improve the β-GLU properties, converting soybean isoflavone glycoside to their aglycones form.

Ultrasound-assisted assembly of β-lactoglobulin and chlorogenic acid for non covalent nanocomplex: fabrication, characterization and potential biological function

It is essential to understand the ultrasound-induced changes in assembly of proteins and polyphenols into non covalent nanocomplex. β-Lactoglobulin (LG) and chlorogenic acid (CA) with various biological activities can be combined to form food-grade nanocomplexes. This study systematically explored the role of high-intensity ultrasound pretreatment on the binding mechanisms of LG and CA, and the potential biological function for embedding curcumin (Cur). The scanning electron microscopy (SEM) revealed that ultrasound treatment could destroy the structure of LG, and the particle size of the protein was reduced to<50 nm. The change in secondary structure of the protein by ultrasound treatment could be revealed by the fourier transform infrared (FTIR) and fluorescence spectra. Besides, it was found that LG and CA were combined to form a complex under the hydrophobic interaction, and CA was bound in the internal cavity of LG with a relatively extended conformation. The result demonstrated that the ratio of Cur embedded in the ultrasonic sample could be effectively increased by 7% - 10%, the particle size in the emulsion was smaller, and the dispersion was more stable. This work contributes to the development of protein-polyphenol functional emulsion systems with the ability to deliver Cur.

Physicochemical and Functional Modifications of Hemp Protein Concentrate by the Application of Ultrasonication and pH Shifting Treatments

According to the Food and Agriculture Organization (FAO), protein demand is expected to increase globally by around 40% by 2030 as a response to the world's population growth. Due to their clean label, vegan or vegetarian based applications, nutritional value, and cost-efficient properties, plant-based proteins have been widely studied. However, most of the alternatives currently found in the market have some challenges because of their poor solubility, emulsifying, gelling, and foaming attributes. Hemp seed protein has gained increasing attention due to its unique amino acids and fatty acids profiles. In this study, commercial HPC mixtures were adjusted to pH 2, 4, 6, 8, 10, and 12 followed by ultrasonication (US) for 5 min (5 s on: 5 s off) and incubated for an hour before neutralizing to pH 7. Following the treatments, the samples were analyzed for their hydrodynamic diameter, conductivity, zeta potential, polydispersity index, surface hydrophobicity, solubility, electrophoresis (SDS-PAGE), free sulfhydryl group, and optical characteristics. The samples treated with ultrasound at pH 8 and 10 significantly (p < 0.05) enhanced the solubility of the hemp seed protein by 12.12% and 19.05%, respectively. Similarly, the samples treated with ultrasonication and pH shifting at pH 6, 8, and 10 also significantly increased the amount of free sulfhydryl content (p < 0.05) to 41.6, 58.72, and 46.54 mmol/g from 32.8 mmol/g, respectively. This study shows that the application of ultrasonication and pH shifting is a promising alternative method to modify the functional properties of HPC and widen their applications in the food, cosmetics, and pharmaceutical industries.