Investigation into predominant peptide and potential allergenicity of ultrasonicated β-lactoglobulin digestion products

Interactions between β-lactoglobulin and polyphenols: Mechanisms, properties, characterization, and applications

β-lactoglobulins (βLGs) have a wide range of applications in food because of their ability to emulsify, foam, and gel. This makes them good functional additives. However, their performance depends on temperature, pH, and mineral levels, so their functional qualities are limited in particular applications. How polyphenols (PPs) interact with βLG is crucial for the functional characteristics and quality of dietary compounds. In most food systems, a spontaneous interaction between proteins and PPs results in a "protein-PP conjugate," which is known to affect the sensory, functional, and nutraceutical qualities of food products. The βLG-PP conjugates can be used to enhance the quality of food. This article emphasizes analytical techniques for describing the characteristics of βLG-PP complexes/conjugates. It also goes over the functions of βLG-PP conjugates, including their solubility, thermal stability, emulsifying, and antioxidant qualities. The majority of βLG-PPs interactions is due to non-covalent (H-bonding, electrostatic interactions) or covalent bonds that are mostly caused by βLG or PP oxidation through enzymatic or non-enzymatic mechanisms. Furthermore, the conformation or type of proteins and PPs, as well as environmental factors like pH and temperature, have a significant impact on proteins-PPs interactions. Higher thermal stability, antioxidant activities, and superior emulsifying capabilities of the βLG-PP conjugates make them useful as innovative additives to enhance the quality and functions of food products.

Combined processing technologies: Promising approaches for reducing Allergenicity of food allergens

Food allergy is a severe threat to human health. Although processing technologies are widely used to reduce allergenicity, hypoallergenic foods produced by a single processing technology cannot satisfy consumer demands. Combined processing technology (CPT) is a promising strategy for efficiently producing high-quality hypoallergenic foods. This paper reviews the effects of CPT on the allergenicity of food allergens from three aspects: physical-biochemical CPT, biochemical-biochemical CPT, and physical-physical CPT. The synergistic mechanisms, strengths, and limitations of these technologies were discussed. It was found that CPT is generally more effective than single-processing technologies. Physical-biochemical CPT is the most widely studied and well-established because physical and biochemical processing technologies complement each other and effectively disrupt conformational and linear epitopes. Biochemical-biochemical CPT primarily disrupts linear epitopes, but most methods are time-consuming. Physical-physical CPT is the least studied; they mainly disrupt conformational epitopes and only rarely affect linear epitopes.

A comprehensive review of effects of ultrasound pretreatment on processing technologies for food allergens: Allergenicity, nutritional value, and technofunctional properties and safety assessment

Many proteins are essential food components but also major allergens. Reducing protein allergenicity while preserving its nutritional value and technofunctional properties has always been the goal of the food industry. Ultrasound (US) is a green processing method for modifying proteins. In addition, US pretreatment combined with other processing techniques (USPCT) has been increasingly used in the food industry. Therefore, this review presents an overview of recent advances in the impact of US and USPCT (US-combined enzymatic hydrolysis [USCE], US-combined glycation [USCG], and US-combined polyphenol conjugation [USCP]) on the allergenicity, nutritional value, and technofunctional properties of food allergens. We discuss the potential mechanisms, advantages, and limitations of these technologies for improving the properties of proteins and analyze their safety, challenges, and corresponding solutions. It was found that USPCT can improve the efficiency and effectiveness of different methods, which in turn can be more effective in reducing protein allergenicity and improving the nutritional value and functional properties of processed products. Future research should start with new processing methods, optimization of process conditions, industrial production, and the use of new research techniques to promote technical progress. This paper is expected to provide reference for the development of high-quality hypoallergenic protein raw materials.

Localization and antigenicity reduction of immunodominant conformational IgE epitopes on αs1-casein

αs1-Casein (αs1-CN) is the major allergen in cow milk; however, the understanding of its conformational epitopes remains limited due to the absence of a well-defined three-dimensional structure, which has impeded efforts to effectively reduce its antigenicity. This study employed molecular dynamics simulations (MD), ELISA, cell assays and peptidomes analysis to investigate the critical conformational epitopes of αs1-Casein. MD and immunological analyses identified a dominant conformational epitope encompassing the regions S55-E75 & Y154-T174 & F179-W199, which exhibited strong binding affinity to IgE and triggered the releasing of β-hexosaminidase, histamine and IL-6 in KU812 cells, thereby inducing allergic responses. Notably, the segments Y154-T174 and F179-W199 were particularly impactful. Furthermore, the presence of helical structures within the epitopes enhanced their binding to IgE to a certain extent. Peptidomes analysis further revealed that papain efficiently disrupted the key epitope (Y154-T174) by selectively cleaving the hotspot amino acid residues (Y154 and Y165), thereby significantly reducing the antigenicity of αs1-CN, decreasing IgE and IgG binding to 7.28 % and 10.39 %, respectively. These findings enhance the understanding of αs1-CN's antigenic epitopes and provides a theoretical and technical foundation for the targeted reduction of its antigenicity.

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.

Research progress in ultrasound and its assistance treatment to reduce food allergenicity: Mechanisms, influence factor, application and prospect

Food allergy is a serious public health problem, which is mainly induced by food allergens (mainly allergenic proteins). Ultrasound can change protein structure, suggesting its potential to decrease food allergenicity. The review concluded the mechanism and influence factors of ultrasound to reduce food allergenicity. The effects of ultrasound alone on some major allergenic foods such as tree nuts, shellfish, fish, egg, soy, milk, and wheat were also discussed. Moreover, ultrasound pre- and post-treatments were combined with heating, glycation, germination, hydrolysis, fermentation, irradiation and polyphenol treatment for reducing food allergenicity were also evaluated. It was found that ultrasound induced structural changes even degradation of protein to reduce the allergenicity mainly due to cavitation effects. The reduction of allergenicity through ultrasound alone was affected by ultrasound power, time, frequency and food types, while, apart from these factors, it was affected by ultrasound order and the assisted technologies conditions during ultrasound-assisted technologies. Compared to ultrasound alone treatment, the ultrasound-assisted technology exhibited high efficiency of allergenicity reduction because ultrasound treatment caused protein unfolding to accelerate allergen modification of the assisted technologies for masking and disrupting more epitopes. Thus, ultrasound treatment, especially ultrasound-assisted technologies under appropriate conditions, was promising for producing hypoallergenic foods.

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.

Bioactive Dairy-Fermented Products and Phenolic Compounds: Together or Apart

Fermented dairy products (e.g., yogurt, kefir, and buttermilk) are significant in the dairy industry. They are less immunoreactive than the raw materials from which they are derived. The attractiveness of these products is based on their bioactivity and properties that induce immune or anti-inflammatory processes. In the search for new solutions, plant raw materials with beneficial effects have been combined to multiply their effects or obtain new properties. Polyphenols (e.g., flavonoids, phenolic acids, lignans, and stilbenes) are present in fruit and vegetables, but also in coffee, tea, or wine. They reduce the risk of chronic diseases, such as cancer, diabetes, or inflammation. Hence, it is becoming valuable to combine dairy proteins with polyphenols, of which epigallocatechin-3-gallate (EGCG) and chlorogenic acid (CGA) show a particular predisposition to bind to milk proteins (e.g., α-lactalbumin β-lactoglobulin, αs1-casein, and κ-casein). Reducing the allergenicity of milk proteins by combining them with polyphenols is an essential issue. As potential 'metabolic prebiotics', they also contribute to stimulating the growth of beneficial bacteria and inhibiting pathogenic bacteria in the human gastrointestinal tract. In silico methods, mainly docking, assess the new structures of conjugates and the consequences of the interactions that are formed between proteins and polyphenols, as well as to predict their action in the body.

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.

Flavor substances of low-valued red swamp crayfish (Procambarus clarkii) hydrolysates derived from double enzymatic systems

To make better use of low-valued crayfish (Procambarus clarkii), double enzymatic systems containing endopeptidase and Flavourzyme® were applied to investigate their effect on the physicochemical properties and volatile substances of low-valued crayfish. The results demonstrated that the double enzymatic hydrolysis had a positive effect on reduced bitterness and increased umami. Among them, the highest degree of hydrolysis (31.67 %) was obtained using trypsin and Flavourzyme® (TF), which showed 96.32 % of peptides with molecular weight < 0.5 kDa and 101.99 mg/g of free amino acids. The quality and quantity analysis showed that the types and relative contents of volatile compounds especially benzaldehyde, 1-octen-3-ol, nonanal, hexanal, 2-nonanone, 2-undecanonewere increased in the double enzymatic hydrolysis. In addition, the increase of esters and pyrazines was also found in gas chromatography-ion mobility spectrometry (GC-IMS). The results indicated that different enzymatic systems could be performed to enhance the flavor substances of low-valued crayfish. In conclusion, double enzymatic hydrolysis may be used as an advisable technique to promote the high-value utilization of low-valued crayfish and provides valuable information for the shrimp products requiring enzymatic hydrolysis.

Isolation and allergenicity evaluation of glycated α-lactalbumin digestive products and identification of allergenic peptides

This study aimed to isolate and evaluate the allergenicity of glycated α-lactalbumin (ALA) digestive products and identify its allergenic peptides. The digestive products of native-, alone glycated- and ultrasound-assisted glycated ALA (ALA-D, ALA-gal-D, 100ALA-gal-D) were isolated into three fractions (F1, F2 and F3). High-resolution mass spectrometry showed that the digestion-resistant peptides of F2 and F3 mainly distributed in amino acid sequence (AA) 25-31, AA32-53, AA40-53, AA54-60, AA80-90, AA94-104. The allergenicity of the three fractions of glycated ALA was lower than that in ALA-D, indicating glycation of ALA could indeed reduce its allergenicity after digestion. Furthermore, most fractions isolated from high glycation-degree ALA had the lowest allergenicity. The IgG/IgE binding abilities of synthesized peptides indicated that AA94-104 firstly identified by us embodied the strongest allergenicity and might be the potential allergenic peptide. This will provide a theory for preparing hypoallergenic products based on the identified allergenic peptides.

Ultrasound Improved the Non-Covalent Interaction of β-Lactoglobulin with Luteolin: Regulating Human Intestinal Microbiota and Conformational Epitopes Reduced Allergy Risks

The present study aims to investigate the effects of ultrasound on the non-covalent interaction of β-lactoglobulin (β-LG) and luteolin (LUT) and to investigate the relationship between allergenicity and human intestinal microbiota. After treatment, the conformational structures of β-LG were changed, which reflected by the decrease in α-helix content, intrinsic fluorescence intensity and surface hydrophobicity, whereas the β-sheet content increased. Molecular docking studies revealed the non-covalent interaction of β-LG and LUT by hydrogen bond, van der Walls bond and hydrophobic bond. β-LG-LUT complex treated by ultrasound has a lower IgG/IgE binding ability and inhibits the allergic reaction of KU812 cells, depending on the changes in the conformational epitopes of β-LG. Meanwhile, the β-LG-LUT complex affected the composition of human intestinal microbiota, such as the relative abundance of Bifidobacterium and Prevotella. Therefore, ultrasound improved the non-covalent interaction of β-LG with LUT, and the reduction in allergenicity of β-LG depends on conformational epitopes and human intestinal microbiota changes.