Evaluation of the structure-activity relationship between allergenicity and spatial conformation of ovalbumin treated by pulsed electric field

Mechanisms underlying the improvement in foaming properties of ovalbumin via non-covalent binding to polymeric proanthocyanidins from Averrhoa carambola fruits

The strong binding capacity of proanthocyanidins towards proteins provides a potential for natural modification of ovalbumin (OVA) and eventually altering its functionalities. In this study, polymeric proanthocyanidins from the fruit of Averrhoa carambola (APAs) were prepared and structurally characterized, and then the possibility and underlying mechanisms of enhancing OVA foaming properties via non-covalent binding to APAs were evaluated. Procyanidins consisting predominately of epicatechin units connected by both A- and B-type interflavan bonds were identified as APAs principal components. UV-vis absorption, fluorescence, CD, FT-IR spectroscopy and molecular docking results revealed that APAs could bind to OVA to form the ground-state complexes and statically quench the intrinsic fluorescence of OVA. The conformation of OVA was changed by its interaction with APAs, and the main binding forces between them were hydrogen bonding and hydrophobic interactions. Moreover, the surface hydrophobicity, contact angle and surface tension of OVA were declined after complexation with APAs, while the free sulfhydryl content, apparent viscosity and interfacial protein content were increased. The addition of APAs significantly promoted the foaming performance of OVA with an improvement of 15 % in foaming capacity and 7 % in foam stability. These results suggested that APAs might be applied as foaming additives in food industry.

Ultrasound assisted glycation decreased the potential allergenicity through changing epitope and structures of Ses i 3

Ses i 3 is one of the major allergens in sesame, and this study aimed to investigate the effect and mechanism of ultrasound-assisted glycation on the potential allergenicity of Ses i 3. Results showed that the IgG and IgE binding of Ses i 3 was significantly reduced after ultrasound-assisted glycation, and the KU812 cell degranulation results showed a significantly decrease of degranulation in the ultrasound-assisted glycation group, suggesting a reduction in the allergenicity of Ses i 3. Subsequently, results from the contents of free amino groups and available lysine showed that ultrasound pretreatment facilitated the glycation reaction. Moreover, five linear epitopes were predicted, with S-5 (AA 571-582) being identified as the effective B cell linear epitope through solid-phase peptide synthesis and serological experiments. Its spatial location was also determined using a AlphaFold 3 model. Besides, inhibited competitive ELISA results indicated that the addition of inhibitor (S-5) didn't reduce the IgE binding of Ses i 3 in the ultrasound-assisted glycation group, suggesting that ultrasound-assisted glycation might have masked or destroyed the S-5 epitope. Ultraviolet (UV) spectra and intrinsic fluorescence emission spectrum results revealed a blue shift in the maximum absorption peaks, along with a significant reduction in surface hydrophobicity, indicating substantial changes in both secondary and tertiary structures. In conclusion, this study demonstrated that ultrasound-assisted glycation effectively reduced the allergenicity of Ses i 3, with the reduction being closely linked to changes in the S-5 epitope and structures. These findings will provide a basis for the development of hypoallergenic sesame products.

Unveiling the regulatory mechanism of pulsed electric field modified instant soy milk powder: Exploring allergenicity, conformation, and epitopes

Glycinin and β-conglycinin are prominent allergens, limiting the safety of soy and soy products in a wide range of applications. The study investigated the effects of pulsed electric field (PEF) on allergenicity, conformation, and epitopes of instant soy milk powder (ISMP) and the simulated digestion products (SDP), and to preliminarily elucidate the regulatory mechanism using multispectroscopy and peptidomics. The allergenicity of SDP and ISMP treated at 20 and 30 kV/cm were reduced and conformations were altered, especially decrease or disappearance of α-helix, enhancement of random coil, and reduction of hydrogen and disulfide bonds in SDP (P < 0.05). Furthermore, their digestion-resistant linear epitopes (DRLE) were differed, such as RSQSDN, EEEEQRQQ, and SRNPIY, therein N and P might be critical amino acids affecting their allergenicity. Overall, PEF reduced the ISPM allergenicity by altering conformations, increasing sensitivities to gastrointestinal digestive enzymes, and modulating binding sites to IgE by covering or disrupting linear epitopes.

Modulating allergenicity of prawn tropomyosin (penaeus chinensis) via pulsed electric field-induced conformational changes

The effect of electric field intensities (EFIs, 5-20 kV/cm) and treatment times (0.5-2 h) on allergenicity and spatial conformation of prawn tropomyosin was evaluated. The results demonstrated that the IgG and IgE binding capacity of tropomyosin maximally increased by 24.34 % and 29.16 % respectively, followed by a subsequent decrease after 20 kV/cm treatment for 1 h. Interestingly, 5-10 kV/cm treatments significantly decreased the α-helix content (P < 0.05) and fluorescence intensity, while 20 kV/cm treatment promoted extensive spiralization, resulting in a tightly packed structure. The increased flexibility further exposed the hydrolysis sites and strengthened the gastrointestinal digestibility of tropomyosin. Additionally, molecular dynamic simulation indicated that extended EFIs increased structural flexibility and depolymerized the tropomyosin dimers through destroying intermolecular hydrogen bonds (formed within arginine and glutamate), which allowed tropomyosin to be easily recognized by IgG/IgE. Whereas, decrease of solvent-accessibility surface area (SASA), hydrophobic surface area induced conformation folded and caused epitopes masked.

Effects of high voltage pulsed electric field on structural properties and immune reactivity of arginine kinase in Fenneropenaeus chinensis

To evaluate the effect of high voltage pulsed electric field (PEF) treatment (10-20 kV/cm, 5-15 min) on the structural characteristics and sensitization of crude extracts of arginine kinase from Fenneropenaeus chinensis. By simulated in vitro gastric juice digestion (SGF), intestinal juice digestion (SIF) and enzyme-linked immunosorbent assay (ELISA), AK sensitization was reduced by 42.5% when treated for 10 min at an electric field intensity of 15 kV/cm. After PEF treatment, the α-helix content decreased, and the α-helix content gradually changed to β-sheet and β-turn. Compared to the untreated group, the surface hydrophobicity increased and the sulfhydryl content decreased. SEM and AFM analyses showed that the treated sample surface formed a dense porous structure and increased roughness. The protein content, dielectric properties, and amino acid content of sample also changed significantly with the changes in the treatment conditions. Non-thermal PEF has potential applications in the development of hypoallergenic foods.

Changes of structure properties and potential allergenicity of ovalbumin under high hydrostatic pressures

Egg proteins, notably ovalbumin (OVA), contribute to a prevalent form of food allergy, particularly in children. This study aims to investigate the impact of high hydrostatic pressure (HHP) treatment at varying levels (300, 400, 500, and 600 MPa) on the molecular structure and allergenicity of OVA. The structure of HHP-treated OVA was assessed through fluorescence spectroscopy, circular dichroism spectroscopy, and molecular dynamics (MD) simulation. HHP treatment (600 MPa) altered OVA structures, such as α-helix content decreased from 28.07 % to 19.47 %, and exogenous fluorescence intensity increased by 8.8 times compared to that of the native OVA. The free sulfhydryl groups and zeta potential value were also increased with HHP treatment (600 MPa). ELISA analysis and MD simulation unveiled a noteworthy reduction in the allergenicity of OVA when subjected to 600 MPa for 10 min. Overall, this study suggests that the conformational changes in HHP-treated OVA contribute to its altered allergenicity.

Investigation into Potential Allergenicity and Digestion-Resistant Linear Epitopes of Fish Skin Gelatin in Cell-Cultured Meat Scaffolds

As a key component of cell-cultured fish, fish skin gelatin (FSG)-based cell scaffold provides support structures for cell growth, proliferation, and differentiation. However, there are potential allergenicity risks contained in FSG-based scaffolds. In this study, 3D edible scaffolds were prepared by phase separation method and showed a contact angle of less than 90°, which indicated that the scaffolds were favorable for cell adhesion. Besides, the swelling ratio was greater than 200%, implying a great potential to support cell growth. The sequence homology analysis indicated that FSG was prone to cross-reaction with collagen analogues. Additionally, a food allergic model was constructed and represented that mice gavaged with cod FSG exhibited higher levels of specific antibodies, mast cell degranulation, vascular permeability, and intestinal barrier impairment than those gavaged with pangasius and tilapias FSG. Its higher allergenicity might be attributed to a higher number of digestion-resistant linear epitopes. Moreover, the higher hydrolysis degree linked to the exposure of linear epitopes to promote the combination with IgE, which was also responsible for maintaining the higher allergenicity of cod FSG. This study clarifies allergenic risks in cell-cultured fish and further study will focus on the allergenicity reduction of FSG-based cell scaffolds.

Traditional cooking methods decreased the allergenicity of egg proteins

Egg allergy is one of the most common food allergies globally. This study aimed to assess the impact of four traditional cooking methods on the allergenicity of egg proteins using a comprehensive strategy, including simulated gastrointestinal digestion in vitro, serology experiments, a rat basophilic leukemia (RBL)-2H3 cell degranulation model, and a passive cutaneous anaphylaxis (PCA) mice model, and the structure changes were detected by circular dichroism (CD) spectra and ultraviolet (UV) spectra. The results showed that the processed egg proteins were more readily digested compared to raw egg proteins. The serological experiments revealed a significant reduction in immunoglobulin E binding of egg proteins after thermal treatments (p < 0.05), particularly after frying. Subsequently, the RBL-2H3 cell degranulation experiment demonstrated a marked decrease in the level of egg allergens-induced β-hexosaminidase release after cooking (p < 0.05). Moreover, the results from the PCA mice model indicated that the increase in vascular permeability was effectively relieved in the treated groups, especially in frying group (p < 0.05). Additionally, the α-helix and β-turn contents of processed egg proteins were significantly decreased (p < 0.05) compared with native egg proteins. The UV spectra findings showed that all cooking treatments caused significant alterations in the tertiary structure, and fluorescence analysis indicated that cooking decreased the surface hydrophobicity of egg proteins. In conclusion, four traditional cooking methods reduced the allergenicity of egg proteins, particularly frying, and this reduction was associated with structural changes that could contribute to the destruction or masking of epitopes of egg allergens. PRACTICAL APPLICATION: Egg allergy has a serious impact on public health, and there is no ideal treatment method at present. This study demonstrated that four traditional cooking methods (boiling, steaming, baking, and frying) reduced the allergenicity of egg proteins, especially frying, and the results will provide a basis for the development of hypoallergenic egg products.

Conformation-Activity Mechanism of Alcalase Hydrolysis for Reducing In Vitro Allergenicity of Instant Soy Milk Powder

Effective reduction of the allergenicity of instant soy milk powder (ISMP) is practically valuable for expanding its applications. This study optimized the enzymolysis technology of ISMP using single-factor experiments and response surface methodology, combined serological analysis, cellular immunological models, bioinformatics tools, and multiple spectroscopy techniques to investigate the effects of alcalase hydrolysis on allergenicity, spatial conformation, and linear epitopes of ISMP. Under the optimal process, special IgE and IgG1 binding abilities and allergenic activity to induce cell degranulation of alcalase-hydrolyzed ISMP were reduced by (64.72 ± 1.76)%, (56.79 ± 3.72)%, and (73.3 ± 1.19)%, respectively (P < 0.05). Moreover, the spatial conformation of instant soy milk powder hydrolysates (ISMPH) changed, including decreased surface hydrophobicity, a weaker peak of amide II band, lower contents of α-helix and β-sheet, and an enhanced content of random coil. Furthermore, the linear epitopes of major soy allergens, 9 from glycinin and 13 from β-conglycinin, could be directionally disrupted by alcalase hydrolysis. Overall, the structure-activity mechanism of alcalase hydrolysis to reduce ISMP allergenicity in vitro was preliminarily clarified. It provided a new research direction for the breakthrough in the desensitization of ISMP and a theoretical basis for revealing the potential mechanism of alcalase enzymolysis to reduce the allergenicity of ISMP.

Ovalbumin interaction with polystyrene and polyethylene terephthalate microplastics alters its structural properties

Contaminating microplastics can interact with food proteins in the food matrix and during digestion. This study investigated adsorption of chicken egg protein ovalbumin to polystyrene (PS, 110 and 260 μm) and polyethylene terephthalate (PET, 140 μm) MPs in acidic and neutral conditions and alterations in ovalbumin structure. Ovalbumin adsorption affinity depended on MPs size (smaller > larger), type (PS > PET) and pH (pH 3 > pH 7). In bulk solution, MPs does not change ovalbumin secondary structure significantly, but induces loosening (at pH 3) and tightening (at pH 7) of tertiary structure. Formed soft corona exclusively consists of full length non-native ovalbumin, while in hard corona also shorter ovalbumin fragments were found. At pH 7 soft corona ovalbumin has rearranged but still preserved level of ordered secondary structure, resulting in preserved thermostability and proteolytic stability, but decreased ability to form fibrils upon heating. Secondary structure changes in soft corona resemble changes in native ovalbumin induced by heat treatment (80 °C). Ovalbumin is abundantly present in corona around microplastics also in the presence of other egg white proteins. These results imply that microplastics contaminating food may bind and change structure and functional properties of the main egg white protein.

Degree of hydrolysis is a poor predictor of the sensitizing capacity of whey- and casein-based hydrolysates in a Brown Norway rat model of cow's milk allergy

The use of infant formulas (IFs) based on hydrolyzed cow's milk proteins to prevent cow's milk allergy (CMA) is highly debated. The risk of sensitization to milk proteins induced by IFs may be affected by the degree of hydrolysis (DH) as well as other physicochemical properties of the cow's milk-based protein hydrolysates within the IFs. The immunogenicity (specific IgG1 induction) and sensitizing capacity (specific IgE induction) of 30 whey- or casein-based hydrolysates with different physicochemical characteristics were compared using an intraperitoneal model of CMA in Brown Norway rats. In general, the whey-based hydrolysates demonstrated higher immunogenicity than casein-based hydrolysates, inducing higher levels of hydrolysate-specific and intact-specific IgG1. The immunogenicity of the hydrolysates was influenced by DH, peptide size distribution profile, peptide aggregation, nano-sized particle formation, and surface hydrophobicity. Yet, only the surface hydrophobicity was found to affect the sensitizing capacity of hydrolysates, as high hydrophobicity was associated with higher levels of specific IgE. The whey- and casein-based hydrolysates exhibited distinct immunological properties with highly diverse molecular composition and physicochemical properties which are not accounted for by measuring DH, which was a poor predictor of sensitizing capacity. Thus, future studies should consider and account for physicochemical characteristics when assessing the sensitizing capacity of cow's milk-based protein hydrolysates.

Covalent polyphenols-proteins interactions in food processing: formation mechanisms, quantification methods, bioactive effects, and applications

Proteins and polyphenols are abundant in the daily diet of humans and their interactions influence, among other things, the texture, flavor, and bioaccessibility of food. There are two types of interactions between them: non-covalent interactions and covalent interactions, the latter being irreversible and more powerful. In this review, we systematically summarized advances in the investigation of possible mechanism underlying covalent polyphenols-proteins interaction in food processing, effect of different processing methods on covalent interaction, methods for characterizing covalent complexes, and impacts of covalent interactions on protein structure, function and nutritional value, as well as potential bioavailability of polyphenols. In terms of health promotion of the prepared covalent complexes, health effects such as antioxidant, hypoglycemic, regulation of intestinal microbiota and regulation of allergic reactions have been summarized. Also, the possible applications in food industry, especially as foaming agents, emulsifiers and nanomaterials have also been discussed. In order to offer directions for novel research on their interactions in food systems, nutritional value, and health properties in vivo, we considered the present challenges and future perspectives of the topic.

Insight into the allergenicity and structure changes of parvalbumin from Trachinotus ovatus induced by dense-phase carbon dioxide

Parvalbumin (PV) is a major allergen in fish, and traditional treatments cannot reduce its sensitization. The effects of dense-phase carbon dioxide (DPCD) treatment on the sensitization and spatial structure of PV in Trachinotus ovatus were evaluated in this study. Western blotting and indirect ELISA were used to determine the allergenicity changes and spatial conformations of PV treated by DPCD. Tris-tricine-SDS-PAGE, circular dichroism, surface hydrophobicity, endogenous fluorescence, UV spectrophotometry, free amino group, total sulfhydryl group and SEM analyses were applied to characterize PV structure. The results showed that DPCD treatment (15 MPa, 30 min, 50 °C) could reduce PV-induced allergic reactions by 39-41 %, which destroyed the normal conformational epitopes and reduced the risk of PV-induced allergy. The secondary structure changed from ordered to disordered with a decreased content of α-helical groups, while the internal hydrophobic groups were exposed. The total sulfhydryl group content decreased significantly (P < 0.05). The surface hydrophobicity and ultraviolet absorption spectrum were enhanced, and the endogenous fluorescence peak shifted to a long wavelength. Meanwhile, the content of free amino groups increased significantly (P < 0.05). This study could provide a theoretical basis and a promising technical approach for reduction of PV allergenicities.

Pulsed electric field treatment of soymilk: Impact on Kunitz trypsin inhibitor allergenicity, antinutritional factor, and aroma characteristics

Allergens, antinutritional factors, and lipoxygenase (LOX) enzyme present in soymilk limit its consumption as vegan milk. Therefore, the present study focuses on reducing these limiting factors using pulsed electric field (PEF) treatment. In this regard, 20-40 kV/cm electric field was applied to soymilk for the effective treatment periods of 450, 1350, and 2250 ms. After the treatment, a reduction in pH (6.60 ± 0.10 to 6.47 ± 0.12) and an increase in the conductivity (173.03 ± 0.40 to 177.33 ± 0.72 µS) were observed. Furthermore, FTIR (Fourier Transform Infrared Spectroscopy), UV (Ultra Violet) intrinsic spectra, and CD (Circular Dichroism) spectra (α-helix reduction and β-sheet increase) data indicated mild structural changes in the proteins of soymilk. As a result, PEF treatment reduced the soymilk allergenicity (67.33 ± 20.48%), LOX activity (69.45 ± 9.38%), and trypsin inhibitor activity (75.61 ± 4.04%). Apart from that, the color, viscosity, and volatiles of soymilk also had significant changes due to PEF treatment. The aroma changes in PEF-treated soymilk were highly influenced by two major principal component (PC1 & PC2) groups and they accounted for about 70% of the aroma variations. However, these changes were mild and did not induce any off-flavors and the treatment remained effective against the quality hazards like allergens, antinutritional factors, and LOX enzyme. PRACTICAL APPLICATION: PEF treatment of soymilk reduces the possible allergic reactions in human body at least by 30%. Further, it reduces the antinutritional factor and off-odor inducing compounds. Therefore, the PEF treatment can be used in industries as a pre-treatment to produce allergen and antinutritional compounds free protein isolates from soybeans.

Food Allergens: When Friends Become Foes-Caveats and Opportunities for Oral Immunotherapy Based on Deactivation Methods

Food allergies represent a serious health concern and, since the 1990s, they have risen gradually in high-income countries. Unfortunately, the problem is complex because genetic, epigenetic, and environmental factors may be collectively involved. Prevention and diagnoses have not yet evolved into efficacious therapies. Identification and control of allergens present in edible substances hold promise for multi-purpose biomedical approaches, including oral immunotherapy. This review highlights recent studies and methods to modify the otherwise innocuous native proteins in most subjects, and how oral treatments targeting immune responses could help cancel out the potential risks in hypersensitive individuals, especially children. We have focused on some physical methods that can easily be conducted, along with chemo-enzymatic modifications of allergens by means of peptides and phytochemicals in particular. The latter, accessible from naturally-occurring substances, provide an added value to hypoallergenic matrices employing vegetal wastes, a point where food chemistry meets sustainable goals as well.

Research progress in the application of emerging technology for reducing food allergens as a global health concern: A systematic review

Since the turn of the century, innovative food processing techniques have quickly risen to the top of the commercial and economic prominence food industry's priority list due to their many benefits over more conventional approaches. Compared to traditional food processing techniques, these innovative procedures retain better the distinctive aspects of food, including its organoleptic and nutritional attributes. Concurrently, there has been a discernible increase in the number of people, particularly infants and young children, who are allergic to certain foods. Although this is widely associated with shifting economic conditions in industrialized and developing countries, the rise of urbanization, the introduction of new eating patterns, and developments in food processing, it still needs to be determined how exactly these factors play a part. Under this circumstance, given the widespread presence of allergens that cause IgE-mediated reactions, it is critical to understand how the structural changes in protein as food is processed to determine whether the specific processing technique (conventional and novel) will be appropriate. This article discusses the impact of processing on protein structure and allergenicity and the implications of current research and methodologies for developing a platform to study future pathways to decrease or eliminate allergenicity in the general population.

Allergenicity, assembly and applications of ovalbumin in egg white: a review

Ovalbumin (OVA), the most abundant protein in egg whites, has been widely used in various industries. Currently, the structure of OVA has been clearly established, and the extraction of high-purified OVA has become feasible. However, the allergenicity of OVA is still a serious problem because it can cause severe allergic reactions and may even be life-threatening. The structure and allergenicity of the OVA can be altered by many processing methods. In this article, a detailed description on the structure and a comprehensive overview on the extraction protocols and the allergenicity of OVA was documented. Additionally, the information on assembly and potential applications of OVA was summarized and discussed in detail. Physical treatment, chemical modification, and microbial processing can be applied to alter the IgE-binding capacity of OVA by changing its structure and linear/sequential epitopes. Furthermore, research indicated that OVA could assemble with itself or other biomolecules into various forms (particles, fibers, gels, and nanosheets), which expanded its application in the food field. OVA also shows excellent application prospects, including food preservation, functional food ingredients and nutrient delivery. Therefore, OVA demonstrates significant investigation value as a food grade ingredient.

Research advance of non-thermal processing technologies on ovalbumin properties: The gelation, foaming, emulsification, allergenicity, immunoregulation and its delivery system application

Ovalbumin (OVA) is the most abundant protein in egg white, with excellent functional properties (e.g., gelling, foaming, emulsifying properties). Nevertheless, OVA has strong allergenicity, which is usually mediated by specific IgE thus results in gut microbiota dysbiosis and causes atopic dermatitis, asthma, and other inflammation actions. Processing technologies and the interactions with other active ingredients can influence the functional properties and allergic epitopes of OVA. This review focuses on the non-thermal processing technologies effects on the functional properties and allergenicity of OVA. Moreover, the research advance about immunomodulatory mechanisms of OVA-mediated food allergy and the role of gut microbiota in OVA allergy was summarized. Finally, the interactions between OVA and active ingredients (such as polyphenols and polysaccharides) and OVA-based delivery systems construction are summarized. Compared with traditional thermal processing technologies, novel non-thermal processing techniques have less damage to OVA nutritional value, which also improve OVA properties. OVA can interact with various active ingredients by covalent and non-covalent interactions during processing, which can alter the structure or allergic epitopes to affect OVA/active components properties. The interactions can promote OVA-based delivery systems construction, such as emulsions, hydrogels, microencapsulation, nanoparticles to encapsulate bioactive components and monitor freshness for improving foods quality and safety.

The microstructure and thermal properties of pulsed electric field pretreated oxidized starch

The structure and thermal properties of pulsed electric field (PEF) assisted sodium hypochlorite oxidized starch were investigated. The carboxyl content of the oxidized starch was increased by 25 % when compared with the traditional oxidation method. Dents and cracks were evident on the surface of the PEF-pretreated starch. Compared with native starch, the peak gelatinization temperature (T_p) of PEF-assisted oxidized starch (POS) was reduced by 10.3 °C, while that of the oxidized starch without PEF treatment (NOS) was only reduced by 7.4 °C. In addition, PEF treatment further reduces the viscosity and improve the thermal stability of the starch slurry. Therefore, PEF treatment combined with hypochlorite oxidation is an effective method to prepare oxidized starch. PEF showed great potential in expanding starch modification, to promote a wider application of oxidized starch in the paper, the textile and the food industry.

Pulsed Electric Field-Assisted Alcalase Treatment Reduces the Allergenicity and Eliminates the Antigenic Epitopes of Ovomucoid

Physically assisted chemical modifications can effectively reduce the allergenicity of ovomucoid (OVM). However, only a few studies have used pulsed electric field (PEF)-assisted alcalase hydrolysis to reduce the allergenicity of OVM. Herein, we investigated the effect of PEF-assisted alcalase treatment on the spatial conformation, allergenicity, and antigenic epitopes of OVM based on multispectroscopic analyses, bioinformatics, and mass spectrometry. The results showed that PEF-assisted alcalase treatment promoted the hydrolysis of OVM; moreover, the α-helix content and surface hydrophobicity of OVM significantly decreased, which disordered its spatial conformation and weakened its intermolecular interactions. Additionally, enzyme-linked immunosorbent assay (ELISA) results showed that the PEF-assisted alcalase treatment significantly reduced the binding levels of IgE and IgG1, which were 47.66 and 36.41%, respectively. Finally, eight epitopes of OVM were obtained by immunoinformatic tools. Nano-high performance liquid chromatography coupled to tandem mass spectrometry (nano-HPLC MS/MS) results showed that the hydrolysate of OVM and alcalase (HOVM) had nine more peptide-containing epitopes than the hydrolysate of PEF-treated OVM and PEF-treated alcalase (HOVM-PP'), indicating that PEF could promote the elimination of linear epitopes in OVM, thereby reducing OVM allergenicity.

Evaluating the influence of cold plasma bubbling on protein structure and allergenicity in sesame milk

BACKGROUND

Sesame is a traditional oilseed comprising essential amino acids. However, the presence of allergens in sesame is a significant problem in its consumption; thus, this study attempted to reduce these allergens in sesame oilseeds.

OBJECTIVE

The present study aimed to evaluate the effect of cold plasma processing on structural changes in proteins, and thereby the alteration of allergenicity in sesame milk. Method: Sesame milk (300 mL) was processed using atmospheric pressure plasma bubbling unit (dielectric barrier discharge, power: 200 V, and airflow rate: 16.6 mL/min) at different exposure times (10, 20, and 30 min).

RESULTS

The efficiency of plasma-bubbling unit as measured by electron paramagnetic resonance in terms of producing reactive hydroxyl (OH) radicals proved that generation of reactive species increased with exposure time. Further, the plasma-processed sesame milk subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetery analysis revealed that plasma bubbling increased the oxidation of proteins with respect to bubbling time. The structural analysis by Fourier transform infrared spectroscopy and circular dichroism revealed that the secondary structure of proteins was altered after plasma application. This change in the protein structure helped in changing the immunoglobulin E (IgE)-binding epitopes of the protein, which in turn reduced the allergen-binding capacity by 23% at 20-min plasma bubbling as determined by the sandwich-type enzyme-linked immunosorbent assay. However, 30-min plasma bubbling intended to increase allergenicity, possibly because of increase in IgE binding due to the generation of neo epitopes.

CONCLUSION

These changes proved that plasma bubbling is a promising technology in oxidizing protein structure, and thereby reducing the allergenicity of sesame milk. However, increase in binding at 30-min bubbling is to be studied to facilitate further reduction of the binding capacity of IgE antibodies.

Succinylated whey protein isolate-chitosan core-shell composite particles as a novel carrier: Self-assembly mechanism and stability studies

Single protein [whey protein isolate (WPI) or succinylated whey protein isolate (SWPI)] and composite particles of proteins with chitosan (CS) were tested for their ability to encapsulate and protect curcumin (CUR). Combining protein and CS resulted in changes in zeta-potential and surface hydrophobicity, particularly in the SWPI-H (high degree of succinylation, 90 %) and CS composite particle (H-CS). Furthermore, the secondary and tertiary structures were dramatically altered using Fourier transform infrared (FTIR), circular dichroism (CD), and X-ray diffraction (XRD). Scanning electron microscopy (SEM) and atomic force microscope (AFM) analyses revealed that H-CS exhibited a soft core-rigid shell morphology due to electrostatic interactions, hydrophobic interactions, and H-bond interactions. Fluorescence quenching results demonstrated that H-CS had a higher binding constant (K, 1.69 ×104 M-1) and encapsulation effectiveness (EE, 88.3 %) of CUR. Because of increased binding sites and steric hindrance, CUR was stabilized more effectively in H-CS in photostability and thermostability tests,. These results show that SWPI-CS composite particles can be utilized to build a protection system for water-insoluble nutritional supplements.

C-Terminal Modification on the Immunomodulatory Activity, Antioxidant Activity, and Structure–Activity Relationship of Pulsed Electric Field (PEF)-Treated Pine Nut Peptide

In this study, a novel peptide VNAVL was synthesized by removing the C-terminal histidine on the basis of a bioactive peptide VNAVLH obtained from pine nut (Pinus koraiensis Sieb. et Zucc) protein. The effects of removing histidine on antioxidant activity, immunomodulatory activity, and secondary structure of the PEF-treated peptide were discussed. Compared with VNAVLH, VNAVL only exhibited lower antioxidant activity, but no immunomodulatory activity to release TNF-α, IL-6, and NO by activating RAW 264.7 cells. In addition, both antioxidant and immune activities of VNAVLH were significantly more sensitive to treatment with 40 kV/cm than other field intensities, whereas VNAVL was not sensitive to field strength changes. CD spectra and DSSP analysis verified that both peptides consisted of a β structure and random coil, but the ability of VNAVL to transform the random coil via PEF treatment is weaker than that of VNAVLH. Therefore, PEF treatment might expose the key active site located on the C-terminal histidine by altering the secondary structure of the peptide.