Free Sulfhydryl Groups Research Articles

Analysis of the effect mechanism of wet grinding on the film properties of pea protein isolate based on its structure changes

Pea protein isolate (PPI) is a spherical structure with low intermolecular crosslinking, resulting in low tensile strength and hydrophobicity of the PPI film. In this study, wet grinding (WG) treated pea protein isolate was used, and protein films were prepared from the wet-ground pea protein isolate (WG-PPI). The structural changes of WG-PPI were investigated, and the effect mechanism of wet grinding on the properties of PPI films was discussed by the analysis of the relationship between the structural changes of PPI and the properties of PPI films. The results showed that after wet grinding for 10 min, α-helix, and β-turn increased to 12.07% and 31.37% respectively, while β-sheet and random coil decreased to 31.80% and 24.76%. The particle size decreased from 1365.87 nm to 1068.03 nm, and the free sulfhydryl group increased from 3.91 μmol/g to 6.04 μmol/g. Meanwhile, tryptophan residues were exposed. These changes enhanced the protein-protein and protein-glycerol interactions. Therefore, after wet grinding for 10 min, the film opacity decreased to 1.15 A/mm, the water vapor permeability decreased to 3.45 × 10−9·g·m·m−2·s−1·Pa, the contact angle increased from 56.48° to 72.37°, the tensile strength increased from 1.20 MPa to 2.72 MPa, the elongation at break increased from 74.9% to 166.8%, and the surface of the film was uniform and dense. In conclusion, it could be seen that moderate WG could significantly improve the properties of PPI films.

Preparation and Properties of High-Soluble Wheat Gluten Protein Based Meat Analogues.

Wheat gluten protein (WGP) has poor solubility and does not easily form fibrous structures, the meat analogues, prepared from it, have unsatisfactory texture properties and poor water holding capacity. Our previous work indicated that pH-shifting combined with heat treatment can significantly improve the solubility and emulsibility of WGP. Therefore, in this work, WGP was treated by pH-cycling (m-WGP) to improve the solubility and then applied in the preparation of meat analogues by high moisture extrusion. The results indicated that the addition of m-WGP significantly improved the texture characteristics and water holding capacity (282.4%) of the extrudates and made the extrudates show a tighter organizational structure according to the SEM images. Additionally, MRI analysis showed that the addition of m-WGP resulted in a more uniform moisture distribution in the extrudate. And the free sulfhydryl group result showed that the addition of m-WGP significantly increased the free sulfhydryl group content, which was beneficial to the formation of disulfide bonds to enhance the tissue structure. When the addition content of m-WGP was 10%, the gluten extrudate exhibited good water holding capacity and uniform moisture distribution, but the excessive hardness and chewiness were not suitable for simulating meat. When the addition content of m-WGP reached 50%, the gluten extrudate has the closest textural characteristics to commercial plant-based meat and real meat, with the potential to be used as a raw material to simulate meat. Accordingly, this work improves the processing properties of WGP and explores plant-based ingredients for meat analogues. This article is protected by copyright. All rights reserved.

Insight into covalent conjugates of β-lactoglobulin with rutin: Characterizing allergenicity, digestibility, and antioxidant properties in vitro

β-lactoglobulin (β-LG) is an essential nutrient in milk, but it is the primary allergen causing dairy allergy in humans. Currently, researchers are focusing on using flavonoids to covalently modify β-LG for improving its functionality. However, the impact and underlying mechanisms of rutin covalent modification on the functional properties and allergenicity of β-LG remain unclear. Here, we aim to investigate the changes in allergenicity, digestive characteristics, and antioxidant properties of β-LG after covalent modification using a combination of spectroscopy, enzyme-linked immunosorbent assay (ELISA), simulated digestion, and antioxidant assays. The results indicate that rutin forms covalent bonds with the free amino group, sulfhydryl group, and tryptophan of β-LG, leading to alterations in the secondary structure of β-LG. Furthermore, the modified β-LG exhibits improved antioxidant capacity and decreased allergenicity, along with reduced resistance to pancreatin digestion in vitro. This study provides novel insights and strategies to expand the functional application of β-LG.

Modification of whey protein isolate by ultrasound-assisted pH shift for complexation with carboxymethylcellulose: Structure and interfacial properties

The application of whey protein isolate (WPI) is limited because of its compact spherical structure. In this study, ultrasound-assisted pH shift was employed to modify WPI for complexation with carboxymethylcellulose (CMC). The foaming and emulsifying properties of WPI/CMC complexes were investigated. The results demonstrate that the pretreatment of ultrasound-assisted pH 12 shift increased the content of free sulfhydryl groups from 16.5 μmol/g to 34.7 μmol/g and enhanced protein hydrophobicity from 311.4 to 370.6 (p < 0.05). Compared to the complexes formed by untreated WPI and CMC, the complexes pretreated with ultrasound-assisted pH 12 shift had a smaller size of 293.4 nm and a more uniform distribution. Furthermore, WPI/CMC complexes pretreated by ultrasound-assisted pH 12 shift exhibited higher emulsifying activity and emulsion stability index, which were increased by 8.9 % and 42.6 % respectively, in comparison with the control group (p < 0.05). A positive correlation was found between the surface hydrophobicity of WPI and emulsifying activity of WPI/CMC complexes. Ultrasound-assisted pH 2 shift improved the foaming capacity of complexes by 28.3 % over the control (p < 0.05). All the results indicate that the interfacial properties of WPI/CMC complexes can be improved significantly by the combination of pH shift and ultrasound.

Evaluation of ohmic heating modified soybean protein isolate structure and antioxidant film under different catechin concentrations

To produce edible films with excellent antioxidant properties, soy protein isolate (SPI) was pretreated using ohmic heating (OH) to create more catechin binding sites. Compared with untreated SPI, ohmic heating-pretreated SPI (OH-SPI) had a looser secondary structure, higher fluorescence intensity, more free sulfhydryl groups, higher hydrophobicity (H0), and lower protein particles, all of which facilitated covalent binding between SPI and catechin. The binding equivalent of OH-SPI and catechin increased from 128.90 to 237.43 nmol/mg protein. The above results proved that ohmic heating pretreatment benefited the covalent binding between SPI and catechin and the development of the antioxidant film. Scanning electron microscopy (SEM) showed that catechin-modified OH-SPI (OH-SPI-CC) films had a rough and aggregated structure. As the concentration of catechin increased, the mechanical properties of the film improved while the barrier properties slightly decreased. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) confirmed that the cross-linking between catechin and OH-SPI was covalent. In application testing of OH-SPI-CC film, OH-SPI-CC film at a catechin concentration of 4.0 mg/mL (OH-SPI-CC-4) showed the best DPPH and ABTS free radical scavenging rate and the highest cumulative release in food simulators. Therefore, cross-linking catechin with OH-SPI was an effective method for preparing antioxidant films.

Application of magnetic field for improving the frozen deterioration of wheat dough

This study was to investigate the protective effect of magnetic field (MF) on frozen dough processing quality. The texture, microstructure, rheological and physicochemical properties of wheat dough treated by freezing-thawing cycles under different magnetic flux densities (0, 2, 4, 6, 8, and 10 mT) were analyzed. Compared with conventional frozen dough, MF-treated frozen dough had lower hardness and higher elasticity. Scanning electron microscope exhibited that MF treatment minimized the freezing-induced damages on morphology of starch and gluten, which was consistent with the decreased tan δ in rheological analysis. Application of MF facilitated high relative crystallinity and gelatinization enthalpy in starch granules while the depolymerization of gluten macropolymer was inhibited as manifest with more ordered secondary structure and decreased free sulfhydryl groups. The integrated structure in MF-treated frozen dough resulted in lower free water content as shown by low field nuclear magnetic resonance. The results provided valuable knowledge for the MF-assisted freezing technology and made it possible to improve the freezing-induced deteriorations on wheat-based food.

The Effect of Heat Treatment on the Digestion and Absorption Properties of Protein in Sea Cucumber Body Wall.

This study was designed, for the first time, to investigate the effect of oxidation on the digestion and absorption properties of protein in boiled sea cucumber body wall (BSCBW) via simulated digestion combined with everted-rat-gut-sac models. Boiling heat treatments led to protein oxidation in SCBW, manifested by increases in free radical intensity, thiobarbituric acid reactive substances, carbonyl groups, disulfide bonds, dityrosine bonds, advanced glycation end products, protein hydrophobicity and aggregation, and declines in both free sulfhydryl groups and secondary structure transition from α-helix to β-sheet. Boiling for 2 h caused anti-digestion collagen unfolding, provided the action site for protease and improved protein digestion and absorption levels. On the contrary, excessive oxidative modification of 4 h BSCBW resulted in decreased protein digestion and absorption levels. From the perspective of texture, digestion and absorption properties, boiling for 2 h can obtain sea cucumber products with better edible and digestible properties, which is considered to be a better processing condition.

Enhancing the dispersibility of commercial pea protein ingredients using stirred media milling: Potential mechanisms of action

This study found that stirred media milling (SMM) showed great potential in enhancing the functional properties of commercial legume proteins. The effects of SMM on protein dispersibility and structure in 5% pea protein solutions were investigated. The milling increased pea protein dispersibility index from around 12 to 99%, over an 8-fold increase. During milling, the D[4,3] of protein particles decreased from around 122 μm to 320 nm and the magnitude of the zeta potential increased from 21.6 to 30.0 mV. Microscopy analysis revealed that the morphology of the protein particle changed from aggregated, irregular, and dense before milling to uniformly distributed and spherical after milling. And hydrophobic interactions were the primary intramolecular forces maintaining the structure of the water-dispersible protein particles. Intrinsic fluorescence intensity, surface hydrophobicity, and free sulfhydryl group analysis of the pea proteins increased after milling, and there was a net change in the secondary structure of the proteins from β-sheet and random coil to α-helix and β-turn. SDS-PAGE analysis revealed that insoluble protein aggregates transformed into water-dispersible ones after milling. These results suggested that the conformation and aggregate state of protein molecules were changed during milling. This study indicates that the stirred media milling is a simple and effective means of enhancing pea protein dispersibility, which could expand the application of plant protein in the food industry.

Synergistic improvement of quinoa protein heat-induced gel properties treated by high-intensity ultrasound combined with transglutaminase.

Quinoa protein is enriched with a wide range of amino acids, including all nine essential amino acids necessary for the human body, and in appropriate proportions. However, as the main ingredient of gluten-free food, it is difficult for quinoa to form a certain network structure for lack of gluten protein. The aim of this work was to enhance the gel properties of quinoa protein. Therefore, the texture characteristics of quinoa protein treated with different ultrasound intensities coupled with transglutaminase (TGase) were investigated. The gel strength of quinoa protein gel increased markedly by 94.12% with 600 W ultrasonic treatment, and the water holding capacity increased from 56.6% to 68.33%. The gel solubility was reduced and free amino content increased the apparent viscosity and the consistency index. Changes in the free sulfhydryl group and hydrophobicity indicated that ultrasound stretched protein molecules and exposed active sites. The enhanced intrinsic fluorescence intensity at 600 W demonstrated that ultrasonic treatment affected the conformation of quinoa protein. New bands emerged in sodium dodecylsulfate-polyacrylamide gel electrophoresis indicating that high-molecular-weight polymers were generated through TGase-mediated isopeptide bonds. Furthermore, scanning electron microscopy showed that the gel network structure of TGase-catalyzed quinoa protein was more uniform and denser, thereby improving the gel quality of quinoa protein. The results suggested that high-intensity ultrasound combined with TGase would be an effective way to develop higher-quality quinoa protein gel. © 2023 Society of Chemical Industry.

Functionalization of pine kernel protein by pH-shifting combined with ultrasound treatments: Further improvement with increasing acidity

As a novel plant protein, developing various aspects of pine kernel protein (PKP) functionality is essential to meet the demand for protein-rich foods. To achieve this, the PKP was functionalized by a combination of pH-shifting and ultrasound techniques. The solubility, emulsification and droplet stability of the PKP in the pH range suitable to food (pH 3 to 7) were further investigated. The pH 12-shifting was an effective strategy to increase the solubility of PKP under extreme acidic and neutral conditions, characterized by a higher content of β-sheets and random coils, a greater exposure of free sulfhydryl and hydrophobic groups. Furthermore, appropriate ultrasonic power (250 W) further improved the solubility of PKPs by disrupting intermolecular hydrogen and hydrophobic bonds. As the ambient acidity increased, the emulsions exhibited higher viscoelasticity and stronger protein interactions. Especially at pH 3, the oil droplets stabilized by U250-PKP-12 (PKP treated with 250 W ultrasound-assisted pH 12-shifting) were homogeneously dispersed and surrounded by dense protein, maintaining small particle size and large electrostatic repulsion, and there was no apparent creaming or phase separation in the emulsions after 10 days of storage. Thus, the functionality of PKP after pH-shifting combined with ultrasonic treatments is further enhanced by increasing the environmental acidity.

Comprehensive binding analysis of glycated myosin with furan derivatives via glucose by means of multi-spectroscopy techniques and molecular docking simulation

Myosin is an ideal binding receptor for aroma compounds and its functional properties are easily affected by glucose. The study comprehensively clarified the effects of glucose glycation-induced structural modifications of myosin on its binding ability with furan derivatives, including 2-methylfuran, 2-furfural, and 2-furfurylthiol. The results demonstrated that the binding levels of furan derivatives were obviously affected by the glycation levels of myosin due to the changes of myosin structure and surface. The increased glycation levels caused the unfolding of myosin structure and accelerated the aggregation, as were exhibited by the data of zeta potential, particle size, microstructure, and secondary structure. The glycated myosin with wrinkled surfaces favored the significant increase of hydrophobic interactions (31.59–69.50 μg), the more exposure of amino acid residues (3459–6048), the formation of free sulfhydryl groups (16.37–20.58 mmol/104g) and hydrogen bonds. These key (non)covalent linkages accounted for the generation of glycated myosin-odorants complex, including 2-furfurylthiol (29.17–47.87 %), thus enhancing the resultant binding ability as evidenced by the free furan derivatives concentrations, fluorescence quenching and molecular docking simulation analysis. The glycated myosin for 8 h bound highest concentrations of furan derivatives. The results will provide comprehensive data on the retention of aroma compounds in meat products.

PH-induced egg white protein foaming properties enhancement: Insight into protein structure and quantitative proteomic analysis at protein adsorption layer

The foaming properties of egg white protein (EWP) after pH-induced unfolding (pH 2, pH 4, pH 10 and pH 12) and refolding treatment (pH 2–7, pH 4–7, pH 10–7 and pH 12-7 (adjusting the above pH back to 7)) were studied by structure changes and quantitative proteomic analysis. It was found that all pH treatment improved foaming capacity (FC) and foaming stability (FS) of EWP, especially at pH 2 and pH 12, where EWP was in a molten globule state with unfolded structure (especially at pH 12), high surface hydrophobicity (except for pH 12-treated EWP), more free sulfhydryl groups and up-regulated adsorption proteins. However, adjusting the pH back to 7 limited the foaming properties due to protein refolding. Meanwhile the presence of down-regulated proteins was another reason for relatively poor FC at pH 2–7. Notably, the firmest foam and high FS at pH 12-7 were attributed to the generation of aggregates and the long-term stability of adsorbed proteins. The results of quantitative proteomics implied that lysozyme, ovalbumin and protein TENP were identified as key proteins associated with excellent FC at pH 2, pH 12 and pH 12-7, while β-ovomucin contributed the most to FC at pH 2–7. Moreover, protein TENP and ovomucoid were more relevant to maintaining and reducing FS. Overall, this work elucidated the mechanism of pH treatment to enhance the foaming properties of EWP, which would provide the necessary theoretical support for the quality improvement and product development of EWP powder.

Dynamic microfluidic-assisted transglutaminase modification of soy protein isolate-chitosan: Effects on structural and functional properties of the adduct and its antioxidant activity after in vitro digestion

In this study, soy protein isolate (SPI)-chitosan (CS) adducts were prepared by using dynamic microfluidic-assisted transglutaminase (TGase) modification. It was shown that the solubility and degree of binding of SPI-CS adducts prepared by dynamic microfluidic-assisted TGase modification were better. After the samples were treated twice at 400 bar, the degree of binding for SPI-CS adducts increased to 31.97 ± 1.31%, and the solubility increased to 66.25 ± 1.10%. With the increase of microfluidic pressure, the exposed free sulfhydryl groups increased, the particle size reduced, and the surface hydrophobicity first increased and then decreased. Under the action of the pressure generated by microfluidics, the structure of the protein in the SPI-CS adduct was unfolded and transformed from an ordered structure to a disordered one. The SPI-CS adducts prepared with assisted dynamic microfluidic treatment showed significantly higher ABTS radical scavenging rate, DPPH radical scavenging rate and reducing power after in vitro digestion compared with that of SPI-CS adducts prepared with TGase alone. This result indicated that appropriate dynamic microfluidic treatment improved the structural and functional properties of TGase-modified SPI-CS adducts and significantly increased the antioxidant activity after in vitro digestion.

Influence of self-assembly on the reactive sulfhydryl and antioxidant activity of aggregation-prone ovalbumin-derived peptides

Ovalbumin-derived peptides IFYCPIAIM, NIFYCPIAIM and YCPIAIMSA, containing a common region YCPIAIM, were previously identified as aggregation-prone peptides with variable fibril formation. In this study, we elucidated self-assembly mechanisms of the peptides, by determining the influence of self-assembly on sulfhydryl group accessibility. The free sulfhydryl group content and antioxidant capacity results demonstrate that the peptides assemble into β-sheets, possibly involving hydrogen bonding with the sulfhydryl groups. NIFYCPIAIM, IFYCPIAIM and YCPIAIMSA, in decreasing order, had the largest particle size, thioflavin T fluorescence, reactive sulfhydryl group content, and antioxidant activities. This demonstrates that the reactive sulfhydryl group content, which is influenced by the cysteine residue position relative to the N-terminal of the peptide, is dependent on fibrillation. Rheological studies further demonstrated the non-Newtonian shear-thinning behavior of the peptides. The results provide valuable insight on peptide self-assembly, which is imperative for future design of bioactive hydrogels with promising biomechanical properties for biomaterial applications.

Mechanism of Targeted Regulation of Ovalbumin Epitopes by Pulsed Electric Field-Assisted Alcalase Treatment.

Egg is one of the eight major food allergens, and ovalbumin (OVA) is the most abundant allergenic protein in eggs. In this study, the effects of pulsed electric field (PEF)-assisted Alcalase hydrolysis on the spatial conformation and potential allergenicity of OVA were studied, and the mechanism of its inhibiting allergic reactions effect was revealed. PEF-assisted Alcalase hydrolysis increased the degree of hydrolysis, surface hydrophobicity, and free sulfhydryl group content. Moreover, the reduction in the α-helix content, fluorescence intensity, and disulfide bond content suggested that PEF promoted the OVA hydrolysis by Alcalase. Additionally, enzyme-linked immunosorbent assay data indicated that PEF-assisted Alcalase hydrolysis hindered OVA binding to immunoglobulins E and G1. Finally, based on bioinformatics combined with mass spectrometry, PEF-assisted Alcalase reduced OVA-induced allergic reactions by destroying epitopes in OVA. Overall, PEF technology further destroyed the epitopes of allergens by targeting the binding sites of substrates and enzymes to improve the affinity of enzymes and substrates, reducing allergic reactions.

Wound-Healing Material with Antibacterial and Antioxidant Functions, Constructed Using Keratin, Hyperbranched Polymers, and MnO2.

Wound healing, a global medical issue, poses a substantial financial burden. Therefore, developing low-cost and highly efficacious wound-healing materials is essential. In this study, we prepared keratin-hyperbranched polymer hydrogel-M (KHBP-M), a multifunctional composite gel, by mixing reduced keratin containing free sulfhydryl groups extracted from human hair waste, hyperbranched polymer (HBP) with double bonds at the end, and MnO2 nanoparticles prepared using the biological template method. Keratin has intrinsic wound-healing properties, and MnO2 is a wound-healing material with both photothermal antibacterial and reactive oxygen species (ROS)-scavenging abilities. KHBP-M showed antibacterial effects against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. When exposed to irradiation (808 nm), the killing ratio for S. aureus reached 99.99%, which is especially suitable for wound environments. A similar trend was noted for E. coli. The composite hydrogel also showed excellent ROS-scavenging ability and could resist oxidative stress in L929 cells. Furthermore, in an animal model of infected wounds, the KHBP-M hydrogel treated with near-infrared light had the fastest wound-healing rate, reaching 82.98% on day 15. Our study provides a promising wound-healing material, with simple preparation methods, easy access to sources, and low cost involved.

Quantifying the effects of pre-roasting on structural and functional properties of yellow pea proteins

Roasting could modify the protein structure/conformation, contributing to changes in functional properties. Here we investigated the effects of pre-roasting on the extraction efficiency, structural and functional properties of pea protein concentrates and isolates (PPC and PPI) produced from yellow split peas. The shorter roasting times (150 °C, 10 and 20 min) had little effect on protein yields and could increase the solubility of PPC or PPI by ∼ 12% at pH 7 and enhance the solubility of PPI by ∼ 12% (10-min roasting) and ∼ 24% (20-min roasting) at pH 3. However, a longer duration of pre-roasting (150 °C, 30 min) significantly reduced the extraction efficiency of PPC and PPI by ∼ 30% and ∼ 61%, respectively. Meanwhile, pre-roasting had minor effects on SDS-PAGE profiles and the secondary structures of pea proteins but significantly altered tertiary structures by reducing free sulfhydryl groups, increasing disulfide bonds and surface hydrophobicity. As for the emulsifying properties, pre-roasting improved the emulsion ability index (EAI) of PPC and PPI but decreased the emulsion stability index (ESI) of PPC and had no significant effect on PPI. Moreover, PPC and PPI with shorter pre-roasting duration (10 and 20 min) had endothermic peaks and showed a slight decrease in the denaturation temperature (Td) and the onset temperature (To), respectively. Overall, the study demonstrated that controlled pre-roasting at 150 °C for 10 min and 20 min altered protein structures (mainly tertiary structures), improving the solubility and EAI of pea proteins at pH 7, while retaining their thermal properties in comparison to unroasted samples.

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.

Influence of cooking and texture attributes of far infrared radiated Japonica rice during storage

The impact of ceramic far infrared radiation drying (IRD) pretreatment method on cooking and texture properties based on stabilization of rice protein throughout the storage (8 months) of rough japonica rice was determined. Kinetic analysis showed that IRD significantly reduced the production of carbonyl compounds and free sulfhydryl groups by oxidation of byproducts. This may because of IRD prevented the transformation of ordered secondary structures into disordered, with a 3.3% and 6.6% increase in the content of α-helix and β-fold and the exposed hydrophobic area is reduced. During 8 months of storage at 35 °C, water uptake ratio and volume expansion ratio are 13.5% and 74.3% lower than that of air drying. Therefore, IRD can slow down protein oxidation of stored rice and promote the water absorption ability, expansion of rice kernel during gelatinization, and improve rice cooking quality and texture characteristics.

Hydrogen peroxide oxidation modifies the structural properties and allergenicity of the bee pollen allergen profilin

Bee pollen is a byproduct of pollination, which is a necessary process to produce foods. However, bee pollen can induce significant food-borne allergies. We previously identified a bee pollen-derived pan-allergen in the profilin family, Bra c p. Herein, we aimed to reduce Bra c p allergenicity via protein oxidation with hydrogen peroxide and explore the changes induced. Ion-mobility mass spectrometry revealed aggregation of the oxidized product; we also found irreversible sulfonation of the free sulfhydryl group of the Bra c p Cys98 residue to a more stable cysteine derivative. A significant proportion of the α-helices in Bra c p were transformed into β-sheets after oxidation, masking the antigenic epitopes. An immunoassay demonstrated that the IgE-binding affinity of Bra c p was decreased in vitro after oxidation. To our knowledge, this is the first report describing the application of protein oxidation to reduce the allergenicity of profilin family member in foods.