Review of conventional and novel food processing methods on food allergens

Lipid matrix-specific pretreatment method for enhancing the extractability and allergenicity maintenance of bovine milk allergens in ELISA detection

The presence of various components in the food matrix makes allergen detection difficult and inaccurate, and pretreatment is an innovative breakthrough point. Food matrices were categorised based on their composition. Subsequently, a pretreatment method was established using a combination of ultrasound-assisted n-hexane degreasing and weakly alkaline extraction systems to enhance the detection accuracy of bovine milk allergens. Results showed that more allergens were obtained with less structural destruction, as demonstrated using immunological quantification and spectral analysis. Concurrently, allergenicity preservation was confirmed through liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, a KU812 cell degranulation model, and western blotting. The method exhibited good accuracy (bias, 8.47%), repeatability (RSDr, 1.52%), and stability (RSDR, 5.65%). In foods with high lipid content, such as chocolate, the allergen content was 2.29-fold higher than that of commercial kits. Laser confocal scanning microscopy (LCSM) and scanning electron microscopy (SEM) analyses revealed a significant decrease in fat content after post-pretreatment using our method. In addition, colloidal stability surpassed that achieved using commercial kits, as indicated through the PSA and zeta potential results. The results demonstrated the superiority of the extractability and allergenicity maintenance of lipid matrix-specific pretreatment methods for improving the accuracy of ELISA based allergen detection in real food.

Prospects for developing allergen-depleted food crops

In addition to the challenge of meeting global demand for food production, there are increasing concerns about food safety and the need to protect consumer health from the negative effects of foodborne allergies. Certain bio-molecules (usually proteins) present in food can act as allergens that trigger unusual immunological reactions, with potentially life-threatening consequences. The relentless working lifestyles of the modern era often incorporate poor eating habits that include readymade prepackaged and processed foods, which contain additives such as peanuts, tree nuts, wheat, and soy-based products, rather than traditional home cooking. Of the predominant allergenic foods (soybean, wheat, fish, peanut, shellfish, tree nuts, eggs, and milk), peanuts (Arachis hypogaea) are the best characterized source of allergens, followed by tree nuts (Juglans regia, Prunus amygdalus, Corylus avellana, Carya illinoinensis, Anacardium occidentale, Pistacia vera, Bertholletia excels), wheat (Triticum aestivum), soybeans (Glycine max), and kidney beans (Phaseolus vulgaris). The prevalence of food allergies has risen significantly in recent years including chance of accidental exposure to such foods. In contrast, the standards of detection, diagnosis, and cure have not kept pace and unfortunately are often suboptimal. In this review, we mainly focus on the prevalence of allergies associated with peanut, tree nuts, wheat, soybean, and kidney bean, highlighting their physiological properties and functions as well as considering research directions for tailoring allergen gene expression. In particular, we discuss how recent advances in molecular breeding, genetic engineering, and genome editing can be used to develop potential low allergen food crops that protect consumer health.

Food allergen detection by mass spectrometry: From common to novel protein ingredients

Food allergens are molecules, mainly proteins, that trigger immune responses in susceptible individuals upon consumption even when they would otherwise be harmless. Symptoms of a food allergy can range from mild to acute; this last effect is a severe and potentially life-threatening reaction. The European Union (EU) has identified 14 common food allergens, but new allergens are likely to emerge with constantly changing food habits. Mass spectrometry (MS) is a promising alternative to traditional antibody-based assays for quantifying multiple allergenic proteins in complex matrices with high sensitivity and selectivity. Here, the main allergenic proteins and the advantages and drawbacks of some MS acquisition protocols, such as multiple reaction monitoring (MRM) and data-dependent analysis (DDA) for identifying and quantifying common allergenic proteins in processed foodstuffs are summarized. Sections dedicated to novel foods like microalgae and insects as new sources of allergenic proteins are included, emphasizing the significance of establishing stable marker peptides and validated methods using database searches. The discussion involves the in-silico digestion of allergenic proteins, providing insights into their potential impact on immunogenicity. Finally, case studies focussing on microalgae highlight the value of MS as an effective analytical tool for ensuring regulatory compliance throughout the food control chain.

A systematic review on the recent advances of wheat allergen detection by mass spectrometry: future prospects

Wheat is one of the three major staple foods in the world. Although wheat is highly nutritional, it has a variety of allergenic components that are potentially fatal to humans and pose a significant hazard to the growth and consumption of wheat. Wheat allergy is a serious health problem, which is becoming more and more prevalent all over the world. To address and prevent related health risks, it is crucial to establish precise and sensitive detection and analytical methods as well as an understanding of the structure and sensitization mechanism of wheat allergens. Among various analytical tools, mass spectrometry (MS) is known to have high specificity and sensitivity. It is a promising non immune method to evaluate and quantify wheat allergens. In this article, the current research on the detection of wheat allergens based on mass spectrometry is reviewed. This review provides guidance for the further research on wheat allergen detection using mass spectrometry, and speeds up the development of wheat allergen research in China.

Effects of Processing Technology on Protein Separation, Quality, and Functional Characteristics

Proteins provide the material foundation of all life activities and play an important role in the physiological and biochemical metabolism of the human body [...].

New Perspectives on Food Matrix Modulation of Food Allergies: Immunomodulation and Component Interactions

Food allergy is a multifactorial interplay process influenced not only by the structure and function of the allergen itself but also by other components of the food matrix. For food, before it is thoroughly digested and absorbed, numerous factors make the food matrix constantly change. This will also lead to changes in the chemistry, biochemical composition, and structure of the various components in the matrix, resulting in multifaceted effects on food allergies. In this review, we reveal the relationship between the food matrix and food allergies and outline the immune role of the components in the food matrix, while highlighting the ways and pathways in which the components in the food matrix interact and their impact on food allergies. The in-depth study of the food matrix will essentially explore the mechanism of food allergies and bring about new ideas and breakthroughs for the prevention and treatment of food allergies.

Recent advances in soybean protein processing technologies: A review of preparation, alterations in the conformational and functional properties

Currently, growing concerns about sustainable development and health awareness have driven the development of plant-based meat substitutes. Soybean proteins (SPs) are eco-friendly and high-quality food sources with well-balanced amino acids to meet consumer demand. The functionality and physicochemical attributes of SPs can be improved by appropriate processing and modification. With the burgeoning advances of modern processing technologies in the food industry, a multitude of functional foods and ingredients can be manufactured based on SPs. This review mainly highlights the conformational changes of SPs under traditional and emerging processing technologies and the resultant functionality modifications. By elucidating the relationship between processing-induced structural and functional alterations, detailed and systematic insights are provided regarding the exploitation of these techniques to develop different nutritional and functional soybean products. Some popular methods to modify SPs properties are discussed in this paper, including thermal treatment, fermentation, enzyme catalysis, high hydrostatic pressure, high-intensity ultrasound, atmospheric cold plasma, high-moisture extrusion, glycosylation, pulsed ultraviolet light and interaction with polyphenols. Given these processing technologies, it is promising to expand the application market for SPs and boost the advancement of the soybean industry.

Effect of thermal, nonthermal, and combined treatments on functional and nutritional properties of chickpeas

Cicer arietinum or chickpea is an important and highly nutritious pulse, a source of complex carbohydrates, proteins, vitamins, and minerals, considered non-allergenic, and non-GMO crop. Processing technologies play an important role in modifying some chickpea properties and thus increasing its nutritional and health benefits. Herein is summarized and compared the available data on nutritional and functional aspects caused by thermal, nonthermal, and combinations of treatments for chickpea processing. The study focuses on describing the processing conditions necessary to change chickpea matrices aiming to enhance compound bioavailability, reduce anti-nutritional factors and modify functional characteristics for industrial application in product development. Thermal and nonthermal treatments can modify nutrient composition and bioavailability in chickpea matrices. Thermal treatments, moist or dry, prevent microbial spoilage, increase product palatability and increase protein quality. Nonthermal treatments aim to shorten the processing time and use less energy and water sources. Compared to thermal treatments, they usually preserve organoleptic attributes and bioactive compounds in chickpea matrices. Some treatment combinations can increase the efficacy of single treatments. Combined treatments increase antioxidant concentration, protein digestibility and available starch contents. Finally, despite differences among their effects, single and combined treatments can improve the nutritional and physicochemical properties of chickpea matrices.

Designing healthier plant-based foods: Fortification, digestion, and bioavailability

Many consumers are incorporating more plant-based foods into their diets as a result of concerns about the environmental, ethical, and health impacts of animal sourced foods like meat, seafood, egg, and dairy products. Foods derived from animals negatively impact the environment by increasing greenhouse gas emissions, land use, water use, pollution, deforestation, and biodiversity loss. The livestock industry confines and slaughters billions of livestock animals each year. There are concerns about the negative impacts of some animal sourced foods, such as red meat and processed meat, on human health. The livestock industry is a major user of antibiotics, which is leading to a rise in the resistance of several pathogenic microorganisms to antibiotics. It is often assumed that a plant-based diet is healthier than one containing more animal sourced foods, but this is not necessarily the case. Eating more fresh fruits, vegetables, nuts, and whole grain cereals has been linked to improved health outcomes but it is unclear whether next-generation plant-based foods, such as meat, seafood, egg, and dairy analogs are healthier than the products they are designed to replace. Many of these new products are highly processed foods that contain high levels of saturated fat, sugar, starch, and salt, and low levels of micronutrients, nutraceuticals, and dietary fibers. Moreover, they are often rapidly digested in the gastrointestinal tract because processing disrupts plant tissues and releases the macronutrients. Consequently, it is important to formulate plant-based foods to reduce the levels of nutrients linked to adverse health effects and increase the levels linked to beneficial health effects. Moreover, it is important to design the food matrix so that the macronutrients are not digested and absorbed too quickly, but the micronutrients are highly bioavailable. In this article, we discuss how next-generation plant-based foods can be made healthier by controlling their nutrient profile, digestibility, and bioavailability.

Mitigating the allergenicity of peanut allergen Ara h 1 by cold atmospheric pressure argon plasma jet

BACKGROUND

Peanut allergy is recognized as a major food allergy that triggers severe and even fatal symptoms. Avoidance of peanuts in the diet is the main option for current safety management. Processing techniques reducing peanut allergenicity are required to develop other options. Cold plasma is currently considered as a novel non-thermal approach to alter protein structure and has the potential to alleviate immunoreactivity of protein allergen.

RESULTS

The application of a cold argon plasma jet to peanut protein extract could reduce the amount of a 64 kDa protein band corresponding to a major peanut allergen Ara h 1 using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but the overall protein size distribution did not change significantly. A decrease in peanut protein solubility was a possible cause that led to the loss of protein content in the soluble fraction. Immunoblotting and enzyme-linked immunosorbent assay elucidated that the immunoreactivity of Ara h 1 was significantly decreased with the time treated with plasma. Ara h 1 antigenicity reduced by 38% after five scans (approximately 3 min) of cold argon plasma jet treatment, and the reduction was up to 66% after approximately 15 min of treatment.

CONCLUSION

The results indicate that cold argon plasma jet treatment could be a suitable platform for alleviating the immunoreactivity of peanut protein. This work demonstrates an efficient, compact, and rapid platform for mitigating the allergenicity of peanuts, and shows great potential for the plasma platform as a non-thermal technique in the food industry. © 2023 Society of Chemical Industry.

Intrinsic Allergenicity Potential of Salt-Soluble Protein Extracts from the Diploid, Tetraploid and Hexaploid Wheats: Validation Using an Adjuvant-Free Mouse Model

Wheat allergies are potentially life-threatening and, therefore, have become a major health concern at the global level. It is largely unknown at present whether genetic variation in allergenicity potential exists among hexaploid, tetraploid and diploid wheat species. Such information is critical in establishing a baseline allergenicity map to inform breeding efforts to identify hyper-, hypo- and non-allergenic varieties. We recently reported a novel mouse model of intrinsic allergenicity using the salt-soluble protein extract (SSPE) from durum, a tetraploid wheat (Triticum durum). Here, we validated the model for three other wheat species [hexaploid common wheat (Triticum aestivum), diploid einkorn wheat (Triticum monococcum), and the ancient diploid wheat progenitor, Aegilops tauschii], and then tested the hypothesis that the SSPEs from wheat species will exhibit differences in relative allergenicities. Balb/c mice were repeatedly exposed to SSPEs via the skin. Allergic sensitization potential was assessed by specific (s) IgE antibody responses. Oral anaphylaxis was quantified by the hypothermic shock response (HSR). The mucosal mast cell response (MMCR) was determined by measuring mast cell protease in the blood. While T. monococcum elicited the least, but significant, sensitization, others were comparable. Whereas Ae. taushcii elicited the least HSR, the other three elicited much higher HSRs. Similarly, while Ae. tauschii elicited the least MMCR, the other wheats elicited much higher MMCR as well. In conclusion, this pre-clinical comparative mapping strategy may be used to identify potentially hyper-, hypo- and non-allergenic wheat varieties via crossbreeding and genetic engineering methods.

Assessment of the effect of glycation on the allergenicity of sesame proteins

Sesame allergy is a growing concern worldwide. In this study, sesame proteins was glycated with glucose, galactose, lactose and sucrose respectively, and the allergenicity of different glycated sesame proteins were assessed by a comprehensive strategy, including simulated gastrointestinal digestion in vitro, a BALB/c mice model, a rat basophilic leukemia (RBL)-2H3 cell degranulation model and a serological experiment. Firstly, simulated gastrointestinal digestion in vitro showed that glycated sesame proteins were more easily to digest than raw sesame. Subsequently, the allergenicity of sesame proteins was assessed in vivo by detecting the allergic indexes of mice, and results showed that the levels of total immunoglobulin E (IgE) and histamine were reduced in glycated sesame proteins treated mice. Meanwhile, the Th2 cytokines (IL-4, IL-5, and IL-13) were downregulated significantly, demonstrating that sesame allergy was relieved in glycated sesame treated mice. Thirdly, the RBL-2H3 cell degranulation model results showed that the release of β-hexosaminidase and histamine were decreased to different degrees in glycated sesame proteins treated groups. Notably, the monosaccharide glycated sesame proteins exhibited lower allergenicity both in vivo and in vitro. Furthermore, the study also analyzed the structure alteration of sesame proteins, and the results showed that the secondary structure of glycated sesame proteins were changed (the content of α-helix and β-sheet were reduced), and the tertiary structure of sesame proteins after glycation modification was also changed (microenvironment around aromatic amino acids was altered). Besides, the surface hydrophobicity of glycated sesame proteins was also reduced except sucrose glycated sesame proteins. In conclusion, this study demonstrated that glycation reduced the allergenicity of sesame proteins effectively, especially glycation with monosaccharides, and the allergenicity reduction might be related to structural changes. The results will provide a new reference for developing hypoallergenic sesame products.

Effects of Allergen-Specific and Non-Specific AGEs on the Allergenicity of Ovalbumin in a Mouse Model of Food Allergy

SCOPE

Epidemiologic studies suggest a link between the incidence of food allergy and the consumption of dietary advanced glycation end-products (AGEs). However, the pathogenic role of dietary AGEs in food allergy is largely unknown. This study aims to investigate the effect of allergen-specific and non-specific AGEs on the allergenic manifestation of ovalbumin (OVA), a typical food allergen in vivo.

METHODS AND RESULTS

OVA is glycated by methylglyoxal to prepare allergen-specific AGEs (i.e., OVA-AGE), and a standard AIN-93G diet is heated to obtain allergen-non-specific AGEs. A BALB/c mouse model orally sensitizes to OVA with different forms of AGEs is established and the outcomes are measured as clinical signs, specific antibodies, type-2/type-2 cytokines, immune cell subpopulations, intestinal barrier function, and gut microbiota (GM) composition. The OVA-AGE which has a lower immunoglobulin E (IgE)-binding level in vitro does not reduce the allergenicity of OVA but promotes a stronger T helper 2 cells (Th2)-response than native OVA in vivo. Both forms of AGEs up-regulate the expression of splenic RAGE and aggravate the destruction of gut barrier and GM dysbiosis, especially when exposes to non-relevant AGEs.

CONCLUSION

This study highlights the role of dietary AGEs in food allergy and helps to understand the biological consequences of immune-toxic compounds in modern diet.

Food processing to reduce antinutrients in plant-based foods

Antinutrients such as phytic acids, tannins, saponin, and enzyme inhibitors are phytochemicals that can decrease the bioavailability of micro- and macronutrients, thus causing them to be unavailable for absorptions in the digestive system. Antinutrients are a major concern especially in countries where plant-based commodities such as wheat, legumes, and cereals are staple foods, for the antinutrients can cause not only mineral deficiencies, but also lead to more serious health issues. Although various thermal and non-thermal processing methods such as cooking, boiling, and fermentation processes have been practiced to decrease the level of antinutrients, these processes may also undesirably influence the final products. More advanced practices, such as ozonation and cold plasma processing (CPP), have been applied to decrease the antinutrients without majorly affecting the physicochemical and nutritional aspects of the commodities post-processing. This review will cover the types of antinutrients that are commonly found in plants, and the available processing methods that can be used, either singly or in combination, to significantly decrease the antinutrients, thus rendering the foods safe for consumption.

Precautionary Allergen Labeling: What Advice Is Available for Health Care Professionals, Allergists, and Allergic Consumers?

In most countries, the use of precautionary allergen labeling (PAL) is not governed by regulation. PAL was initially identified as a judicious risk management measure to address instances of "unavoidable" cross-contact with priority food allergens during food processing. However, PAL has gradually been devalued in part due to overuse and inconsistent application by the food industry. Currently, most food products do not contain detectable allergen residue or contain only low concentrations of residue of the allergens declared using PAL; however, occasionally, high concentrations of allergen residue are reported, rendering it an ineffective risk communication tool for allergic consumers. In this context, several reasons exist that make the consumption of products bearing a PAL statement not advisable for people with food allergies. The main reason is that the risk is generally not correlated with the statement used by manufacturers. Because of the increased use of PAL on prepackaged food products, and to maximize food choices for allergic individuals, health care professionals increasingly advise some patients considered to be "not highly allergic" to consume products bearing a PAL statement. This article explains why the consumption of products with PAL is not advisable without having a full clinical evaluation and knowledge that an allergen risk assessment has been conducted. It also discusses the perspectives for a better use of PAL on the basis of the recent Food and Agricultural Organization/World Health Organization recommendations on food allergens.

Food preservation by cold plasma from dielectric barrier discharges in agri-food industries

BACKGROUND

Cold plasma (CP) can be defined as partially or wholly ionized gas carrying myriads of highly reactive products, such as electrons, negative ions, positive ions, free radicals, excited or non-excited atoms, and photons at ambient temperature. It is generated at 30-60°C under atmospheric or reduced pressure (vacuum). In contrast to thermal plasma, it requires less power, exhibits electron temperatures much higher than the corresponding gas (macroscopic temperature), and does not present a local thermodynamic equilibrium. Dielectric barrier discharges (DBD) are one of the most convenient and efficient methods to produce CP.

SCOPE AND APPROACH

Cold plasma technology has the potential to replace traditional agri-food processing purification methods because of its low energy requirements and flexible system design. CP technology works by reducing bacteria levels and removing pests and mycotoxins from your produce at harvest. It can also catalyze physiological and biochemical reactions and modify materials. It can meet microbial food safety standards, improve the physical, nutritional, and sensory characteristics of the products, preserve unstable bioactive compounds, and modulate enzyme activities. This manuscript also discusses the quality characteristics of food components before/after CP treatment.

KEY FINDINGS AND CONCLUSION

In the past decade, CP treatments of food products have experienced increased popularity due to their potential contributions to non-thermal food processing. There is no doubt that CP treatment is a flexible approach with demonstrated efficacy for controlling many risks across food and agricultural sustainability sectors. In addition, CP technologies also can be applied in food-related areas, including modification of chemical structures and desensitization treatments. There is a need to fully assess the benefits and risks of stand-alone CP unit processes or their integration as a processing chain as soon as the economic, ecological, and consumer benefits and acceptability are considered.

Sesame as a source of food allergens: clinical relevance, molecular characterization, cross-reactivity, stability toward processing and detection strategies

Sesame is an allergenic food with an increasing allergy prevalence among the European/USA population. Sesame allergy is generally life-persisting, being the cause of severe/systemic adverse immune responses in sesame-allergic individuals. Herein, clinical data about sesame allergy, including prevalence, diagnosis, relevance, and treatments are described, with focus on the molecular characterization of sesame allergens, their cross-reactivity and co-sensitization phenomena. The influence of food processing and digestibility on the stability/immunoreactivity of sesame allergens is critically discussed and the analytical approaches available for their detection in foodstuffs. Cross-reactivity between sesame and tree nuts or peanuts is frequent because of the high similarities among proteins of the same family. However, cross-reactivity phenomena are not always correlated with true clinical allergy in sensitized patients. Data suggest that sesame allergens are resistant to heat treatments and digestibility, with little effect on their immunoreactivity. Nevertheless, data are scarce, evidencing the need for more research to understand the effect of food processing on sesame allergenicity modulation. The demands for identifying trace amounts of sesame in foods have prompted the development of analytical methods, which have targeted both protein and DNA markers, providing reliable, specific, and sensitive tools, crucial for the effective management of sesame as an allergenic food.

Fish Processing and Digestion Affect Parvalbumins Detectability in Gilthead Seabream and European Seabass

Consumption of aquatic food, including fish, accounts for 17% of animal protein intake. However, fish consumption might also result in several side-effects such as sneezing, swelling and anaphylaxis in sensitized consumers. Fish allergy is an immune reaction to allergenic proteins in the fish muscle, for instance parvalbumin (PV), considered the major fish allergen. In this study, we characterize PV in two economically important fish species for southern European aquaculture, namely gilthead seabream and European seabass, to understand its stability during in vitro digestion and fish processing. This information is crucial for future studies on the allergenicity of processed fish products. PVs were extracted from fish muscles, identified by mass spectrometry (MS), and detected by sandwich enzyme-linked immunosorbent assay (ELISA) after simulated digestion and various food processing treatments. Secondary structures were determined by circular dichroism (CD) after purification by anion exchange and gel filtration chromatography. In both species, PVs presented as α-helical and β-sheet structures, at room temperature, were shown to unfold at boiling temperatures. In European seabass, PV detectability decreased during the simulated digestion and after 240 min (intestinal phase) no detection was observed, while steaming showed a decrease (p < 0.05) in PVs detectability in comparison to raw muscle samples, for both species. Additionally, freezing (−20 °C) for up to 12 months continued to reduce the detectability of PV in tested processing techniques. We concluded that PVs from both species are susceptible to digestion and processing techniques such as steaming and freezing. Our study obtained preliminary results for further research on the allergenic potential of PV after digestion and processing.

Detection of Parvalbumin Fish Allergen in Canned Tuna by Real-Time PCR Driven by Tuna Species and Can-Filling Medium

Canned tuna is considered one of the most popular and most commonly consumed products in the seafood market, globally. However, in past decades, fish allergens have been detected as the main concern regarding food safety in these seafood products and are listed as the top eight food allergies. In the group of fish allergens, parvalbumin is the most common. As a thermally stable and calcium-binding protein, parvalbumin can be easily altered with changing the food matrices. This study investigated the effect of a can-filling medium (tomato sauce, spices, and brine solutions) on the parvalbumin levels in canned tuna. The effect of pH, calcium content, and the DNA quality of canned tuna was also investigated before the parvalbumin-specific encoded gene amplification. The presence of fish allergens was determined by melting curve analyses and confirmed by agarose gel electrophoresis. The obtained results showed that the presence of parvalbumin in commercially canned tuna was driven by can-filling mediums, thermal conductivity, calcium content, and the acidity of various ingredients in food matrices. The intra-specific differences revealed a variation in fish allergens that are caused by cryptic species. This study proved that allergens encoding gene analyses by agarose electrophoresis could be used as a reliable approach for other food-borne allergens in complex food matrices.

High hydrostatic pressure treatment reduces the potential antigenicity of β-conglycinin by changing the protein structure during in vitro digestion

BACKGROUND

High hydrostatic pressure (HHP) treatment has been used to alleviate the allergenicity of soybeans, but there are little data about the potential antigenicity of β-conglycinin after HHP treatment.

RESULTS

We examined the effects of HHP treatment on the antigenicity and structure of β-conglycinin. When the pressure was 300 and 400 MPa, HHP treatment reduced the immunoglobulin (Ig)G binding capacity of β-conglycinin, while its IgE binding capacity did not change significantly. After in vitro digestion, both the IgE and IgG binding of β-conglycinin was obviously inhibited after HHP treatment at 400 MPa and 60 °C, although its binding capacity with linear epitope antibodies increased. Moreover, HHP treatment changed the secondary structure of β-conglycinin, the content of α-helix and random coils increased, while the β-sheet and β-turn decreased. After HHP treatment, the conformational structure was unfolded so that a large number of hydrophobic regions were exposed.

CONCLUSION

HHP treatment alleviated the potential antigenicity of β-conglycinin by modifying its structure, which facilitated in vitro digestion and destroyed epitopes. This research provides a new insight into the mechanism of HHP treatment that affects the sensitization of soy protein allergens. © 2022 Society of Chemical Industry.

Investigation of the Mechanism of 60Co Gamma-Ray Irradiation-Stimulated Oxidation Enhancing the Antigenicity of Ovalbumin by High-Resolution Mass Spectrometry

⁶⁰Co gamma-ray irradiation-induced antigenicity changes in ovalbumin (OVA) were investigated, and the molecular mechanism was analyzed. Irradiation treatment at 0-100 kGy could significantly enhance the IgG/IgE binding ability of OVA in a dose-dependent paradigm by concomitant oxidative modification, which exhibited color browning and an increase in carbonyl content caused by high-penetrable rays. More allergenic epitopes of OVA were exposed after irradiation treatment reflected by structural changes including the unfolding of tertiary structure, the conversion of α-helix structures to β-sheet and random coil structures, and the cleavage of several peptide bonds. Meanwhile, three oxidation sites of K46, T49, and N260 located in key linear epitopes were observed, which might increase the allergenic ability of OVA via the disaggregation of noncovalent bonds and the unwinding of α-helix structures. Conclusively, irradiation may enhance the potential allergenicity of OVA by oxidative modification, which provides theoretical guidance for effectively controlling the oxidation of proteins in the irradiation process.

Gastrointestinal fate of food allergens and its relationship with allergenicity

Food allergens are closely related to their gastrointestinal digestion fate, but the changes in food allergens during digestion and related mechanisms are quite complicated. This review presents in detail digestion models for predicting allergenicity, the fates of food allergens in oral, gastric and duodenal digestion, and the applications of digestomics in mapping IgE-binding epitopes of digestion-resistant peptides. Moreover, this review highlights the structure-activity relationships of food allergens during gastrointestinal digestion. Digestion-labile allergens may share common structural characteristics, such as high flexibility, rendering them easier to be hydrolyzed into small fragments with decreased or eliminated allergenicity. In contrast, the presence of disulfide bonds, tightly wound α-helical structures, or hydrophobic domains in food allergens helps them resist gastrointestinal digestion, stabilizing IgE-binding epitopes, thus maintaining their sensitization. In rare cases, digestion leads to increased allergenicity due to exposure of new epitopes. Finally, the action of the food matrix and processing on the digestion and allergenicity of food allergens as well as the underlying mechanisms was overviewed. The food matrix can directly act on the allergen by forming complexes or new epitopes to affect its gastrointestinal digestibility and thereby alter its allergenicity or indirectly affect the allergenicity by competing for enzymatic cleavage or influencing gastrointestinal pH and microbial flora. Several processing techniques attenuate the allergenicity of food proteins by altering their conformation to improve susceptibility to degradation by digestive enzymes. Given the complexity of food components, the food itself rather than a single allergen should be used to obtain more accurate data for allergenicity assessment. PRACTICAL APPLICATION: The review article will help to understand the relationship between food protein digestion and allergenicity, and may provide fundamental information for evaluating and reducing the allergenicity of food proteins.

Deciphering Changes in the Structure and IgE-Binding Ability of Ovalbumin Glycated by α-Dicarbonyl Compounds under Simulated Heating

As a complex reaction, biological consequences of the Maillard reaction (MR) on dietary proteins need to be deciphered. Despite previous studies on the structural and antigenic properties of ovalbumin (OVA) by MR, associated changes induced by specific MR intermediates and their downstream products are largely unknown. This study focused on the impacts of glycation by α-dicarbonyl compounds (α-DCs), intermediates of MR and precursors of advanced glycation end-products (AGEs), on the structural and IgE-binding properties of ovalbumin (OVA) under simulated heating. Methylglyoxal (MGO), glyoxal (GO), and butanedione (BU) were selected as typical α-DCs to generate glycated OVA with different AGE-modifications (AGE-Ms). The results showed that reactions between OVA and α-DCs generated OVA-AGE with various degrees of modification and conformational unfolding, and the reactivity of α-DCs followed the order GO > MGO > BU. Depending on the precursor type, the levels of 10 specific AGEs were verified, and the amounts of total AGEs increased with heating temperature and α-DC dosage. Compared to native OVA, glycated OVA showed reduced IgE-binding levels but with sRAGE-binding ligands, the extent of which was associated with the contents of total AGEs and Nε-carboxymethyllysine, and changes in certain protein conformational structures. High-resolution mass spectrometry further identified different AGE-Ms on the Lys and Arg residues of OVA, confirming variations in the glycation sites and their associations with the immunoreactive epitopes of OVA under different conditions.

Effects of Microwaves, Ultrasonication, and Thermosonication on the Secondary Structure and Digestibility of Bovine Milk Protein

Cow’s milk is considered an excellent protein source. However, the digestibility of milk proteins needs to be improved. This study aimed to evaluate the relationship between the functional properties of milk proteins and their structure upon microwave, ultrasound, and thermosonication treatments. The protein content, digestibility, and secondary-structure changes of milk proteins were determined. The results demonstrated that almost 35% of the proteins in the untreated samples had a α-helix structure and approximately 29% a β-sheet and turns structure. Regarding the untreated samples, the three treatments increased the α-helices and correspondingly decreased the β-sheets and turns. Moreover, the highest milk protein digestibility was observed for the ultrasound-treated samples (90.20–94.41%), followed by the microwave-treated samples (72.56–93.4%), whereas thermosonication resulted in a lower digestibility (68.76–78.81%). The milk protein content was reduced as the microwave processing time and the temperature increased. The final milk protein available in the sample was lower when microwave processing was conducted at 75 °C and 90 °C compared to 60 °C, whereas the ultrasound treatment significantly improved the protein content, and no particular trend was observed for the thermosonicated samples. Thus, ultrasound processing shows a potential application in improving the protein quality of cow’s milk.

Effects of an Electric Field on the Conformational Transition of the Protein: Pulsed and Oscillating Electric Fields with Different Frequencies

The effect of pulsed and oscillating electric fields with different frequencies on the conformational properties of all-α proteins was investigated by molecular dynamics simulations. The root mean square deviation, the root mean square fluctuation, the dipole moment distribution, and the secondary structure analysis were used to assess the protein samples’ structural characteristics. In the simulation, we found that the higher frequency of the electric field influences the rapid response to the secondary structural transitions. However, the conformational changes measured by RMSD are diminished by applying the electrical field with a higher frequency. During the dipole moment analysis, we found that the magnitude and frequency of the dipole moment was directly related to the strength and frequency of the external electric field. In terms of the type of electric fields, we found that the average values of RMSD and RMSF of whole molecular protein are larger when the protein is exposed in the pulsed electric field. Concerning the typical sample 1BBL, the secondary structure analysis showed that two alpha-helix segments both transit to turns or random coils almost simultaneously when it is exposed in a pulsed electric field. Meanwhile, two segments present the different characteristic times when the transition occurs in the condition of an oscillating electric field. This study also demonstrated that the protein with fewer charged residues or more residues in forming α-helical structures display the higher conformational stability. These conclusions, achieved using MD simulations, provide a theoretical understanding of the effect of the frequency and expression form of external electric fields on the conformational changes of the all-α proteins with charged residues and the guidance for anticipative applications.

An overview of tropomyosin as an important seafood allergen: Structure, cross-reactivity, epitopes, allergenicity, and processing modifications

Tropomyosin (TM) is a major allergen in crustaceans, which often causes allergy and is fatal to some consumers. Currently, the most effective treatment is to avoid ingesting TM, although most adverse events occur in accidental ingestion. In this review, the molecular characterization, epitopes, cross-reactivity, and pathogenesis of TM are introduced and elucidated. Modification of TM by traditional processing methods such as heat treatment and enzymatic hydrolysis, and innovative processing technologies including high-pressure treatment, cold plasma (CP), ultrasound, pulsed electric field (PEF), pulsed ultraviolet, microwave and irradiation are discussed in detail. Particularly, enzymolysis, PEF, and CP technologies show great potential for modifying TM and more studies are needed to verify their effectiveness for the seafood industry. Possible mechanisms and the advantages/disadvantages of these technologies for the mitigation of TM allergenicity are also highlighted. Further work should be conducted to investigate the allergenicity caused by protein segments such as epitopes, examine the interaction sites between the allergen and the processing techniques and reveal the reduction mechanism of allergenicity.

Enzymatic crosslinking and food allergenicity: A comprehensive review

Food allergy has become a major global public health concern. In the past decades, enzymatic crosslinking technique has been employed to mitigate the immunoreactivity of food allergens. It is an emerging non-thermal technique that can serve as a great alternative to conventional food processing approaches in developing hypoallergenic food products, owing to their benefits of high specificity and selectivity. Enzymatic crosslinking via tyrosinase (TYR), laccase (LAC), peroxidase (PO), and transglutaminase (TG) modifies the structural and biochemical properties of food allergens that subsequently cause denaturation and masking of the antigenic epitopes. LAC, TYR, and PO catalyze the oxidation of tyrosine side chains to initiate protein crosslinking, while TG initiates isopeptide bonding between lysine and glutamine residues. Enzymatic treatment produces a high molecular weight crosslinked polymer with reduced immunoreactivity and IgE-binding potential. Crosslinked allergens further inhibit mast cell degranulation due to the lower immunostimulatory potential that assists in the equilibration of T-helper (Th)1/Th2 immunobalance. This review provides an updated overview of the studies carried out in the last decade on the potential application of enzymatic crosslinking for mitigating food allergenicity that can be of importance in the context of developing hypoallergenic/non-allergenic food products.

Irradiation technology: An effective and promising strategy for eliminating food allergens

Food allergies are one of the major health concerns worldwide and have been increasing at an alarming rate in recent times. The elimination of food allergenicity has been an important issue in current research on food. Irradiation is a typical nonthermal treatment technology that can effectively reduce the allergenicity of food, showing great application prospects in improving the quality and safety of foods. In this review, the mechanism and remarkable features of irradiation in the elimination of food allergens are mainly introduced, and the research progress on reducing the allergenicity of animal foods (milk, egg, fish and shrimp) and plant foods (soybean, peanut, wheat and nuts) using irradiation is summarized. Furthermore, the influencing factors for irradiation in the elimination of food allergens are analyzed and further research directions of irradiation desensitization technology are also discussed. This article aims to provide a reference for promoting the application of irradiation technology in improving the safety of foods.

Effect of processing technologies on the digestibility of egg proteins

Egg and egg products are a rich source of highly bioavailable animal proteins. Several processing technologies can affect the structural and functional properties of these proteins differently and can influence their fate inside the gastrointestinal tract. The present review examines some of the processing technologies for improving egg protein digestibility and discusses how different processing conditions affect the digestibility of egg proteins under gastrointestinal digestion environments. To provide up-to-date information, most of the studies included in this review have been published in the last 5 years on different aspects of egg protein digestibility. Digestibility of egg proteins can be improved by employing some processing technologies that are able to improve the susceptibility of egg proteins to gastrointestinal proteases. Processing technologies, such as pulsed electric field, high-pressure, and ultrasound, can induce conformational and microstructural changes that lead to unfolding of the polypeptides and expose active sites for further interactions. These changes can enhance the accessibility of digestive proteases to cleavage sites. Some of these technologies may inactivate some egg proteins that are enzyme inhibitors, such as trypsin inhibitors. The underlying mechanisms of how different technologies mediate the egg protein digestibility have been discussed in detail. The proteolysis patterns and digestibility of the processed egg proteins are not always predictable and depends on the processing conditions. Empirical input is required to tailor the optimization of processing conditions for favorable effects on protein digestibility.

Nut Allergenicity: Effect of Food Processing

Nuts are considered healthy foods due to their high content of nutritional compounds with functional properties. However, the list of the most allergenic foods includes tree nuts, and their presence must be indicated on food labels. Most nut allergens are seed storage proteins, pathogenesis-related (PR) proteins, profilins and lipid transfer proteins (LTP). Nut allergenic proteins are characterized by their resistance to denaturation and proteolysis. Food processing has been proposed as the method of choice to alter the allergenicity of foods to ensure their safety and improve their organoleptic properties. The effect of processing on allergenicity is variable by abolishing existing epitopes or generating neoallergens. The alterations depend on the intrinsic characteristics of the protein and the type and duration of treatment. Many studies have evaluated the molecular changes induced by processes such as thermal, pressure or enzymatic treatments. As some processing treatments have been shown to decrease the allergenicity of certain foods, food processing may play an important role in developing hypoallergenic foods and using them for food tolerance induction. This work provides an updated overview of the applications and influence of several processing techniques (thermal, pressure and enzymatic digestion) on nut allergenicity for nuts, namely, hazelnuts, cashews, pistachios, almonds and walnuts.

Processes for reducing egg allergenicity: Advances and different approaches

Egg is a versatile ingredient and ubiquitous food. Nevertheless, egg proteins are a common cause of allergy mainly in childhood. Until now, egg eviction has been the best way to prevent this disorder, however, processed food can contribute to mitigate allergies and to guarantee life quality of allergic individuals. This review focuses on discussing and highlighting recent advances in processes to reduce egg allergenicity as well as new approaches to egg allergy management. In recent times, different methods have been developed to reduce egg allergies, by hiding the epitopes or changing the native or conformational structure of the proteins. Despite processing food has not yet been a solution to completely remove the allergenic potential of egg proteins, innovative strategies, such as addition of phenolic compounds, have been developed with promising results.

Aspects of high hydrostatic pressure food processing: Perspectives on technology and food safety

The last two decades saw a steady increase of high hydrostatic pressure (HHP) used for treatment of foods. Although the science of biomaterials exposed to high pressure started more than a century ago, there still seem to be a number of unanswered questions regarding safety of foods processed using HHP. This review gives an overview on historical development and fundamental aspects of HHP, as well as on potential risks associated with HHP food applications based on available literature. Beside the combination of pressure and temperature, as major factors impacting inactivation of vegetative bacterial cells, bacterial endospores, viruses, and parasites, factors, such as food matrix, water content, presence of dissolved substances, and pH value, also have significant influence on their inactivation by pressure. As a result, pressure treatment of foods should be considered for specific food groups and in accordance with their specific chemical and physical properties. The pressure necessary for inactivation of viruses is in many instances slightly lower than that for vegetative bacterial cells; however, data for food relevant human virus types are missing due to the lack of methods for determining their infectivity. Parasites can be inactivated by comparatively lower pressure than vegetative bacterial cells. The degrees to which chemical reactions progress under pressure treatments are different to those of conventional thermal processes, for example, HHP leads to lower amounts of acrylamide and furan. Additionally, the formation of new unknown or unexpected substances has not yet been observed. To date, no safety-relevant chemical changes have been described for foods treated by HHP. Based on existing sensitization to non-HHP-treated food, the allergenic potential of HHP-treated food is more likely to be equivalent to untreated food. Initial findings on changes in packaging materials under HHP have not yet been adequately supported by scientific data.

Combination Processing Method Reduced IgE-Binding Activity of Litopenaeus vannamei by Modifying Lysine, Arginine, and Cysteine on Multiple Allergen Epitopes

Allergic reactions occur after the whole food is ingested, rather than the purified allergen. The present study explores the low-allergenic food processing for Litopenaeus vannamei by analysis of macrostructure, digestibility, and immunoreactivity. Furthermore, the presence of modified amino acids on the reported IgE epitopes was analyzed by mass spectrometry. Results showed that the combination processing of Maillard reaction (shrimp meat with galactose) with high temperature-pressure at 115 °C obviously changed the macrostructure and increased the digestibility for the shrimp meat. Meanwhile, the processing significantly reduced the IgG/IgE-binding activity of the shrimp meat. The hypo-IgE-binding activity in processed shrimp may be due to the modification of lysine, arginine, and cysteine residues in antigen epitopes. This is a comprehensive assessment of the specific amino acid residues modified by glycation of multiple allergens in processed L. vannamei, which provides a new research method to explore the hypo-IgE-binding activity in food.

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

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

Influence of high-intensity ultrasound on the IgE binding capacity of Act d 2 allergen, secondary structure, and In-vitro digestibility of kiwifruit proteins

Kiwifruit can trigger allergic reactions that can lead to death, causing public health concerns worldwide. In the present study, we treated kiwifruit samples with high-intensity ultrasound (20 kHz, 400 W, 50% duty cycle) for 0 to 16 min to evaluate its effect on the IgE binding capacity of kiwifruit allergen Act d 2, secondary structure and in-vitro digestibility of kiwifruit proteins. The changes in the protein solubility and microstructures of kiwifruit were also analyzed. The results showed that treatment with powerful ultrasound caused a significant disruption in the microstructure of kiwifruit tissues, leading to the changes in the secondary structures of proteins, including a loss of alpha-helixes and an increase in beta-sheet structures. These structural changes were due to the ultrasound treatment, especially 16 min of treatment, resulted in a 50% reduction in Act d 2 allergen content and significantly improved in-vitro digestibility up to 62% from the initial level of 35%. Furthermore, the solubility of the total proteins present in kiwifruit samples was significantly decreased by 20% after 16-min ultrasound processing. The results of this work showed that high-intensity ultrasound treatment has a potential application in reducing the allergenicity of kiwifruit or related products.

Atmospheric cold plasma treatment of soybean protein isolate: insights into the structural, physicochemical, and allergenic characteristics

Currently, there has been a surge of interest in revealing the interactions between plasma and food matrices. In this study, we investigated the impacts of atmospheric cold plasma (ACP) treatment on the structural, physicochemical and allergenic characteristics of soybean protein isolate (SPI). SPI dispersions were subjected to ACP treatments at different frequencies (80 to 100 Hz) and durations (1 to 10 min) to investigate the effects of exposing conditions. Results showed that ACP induced reactive oxygen species-mediated oxidation of soy proteins, resulting in modifications in the secondary and ternary structures of SPI. As a consequence, functional properties of SPI, such as emulsifying (56 to 168%, compared with control) and foaming properties (60 to 194%) were influenced by varying degrees. In addition, under certain circumstance (120 Hz, 5 min), the IgE-binding level of SPI was decreased by up to 75%, when compared to the control. Moderate treatment yielded products with improved functionality and reduced allergenicity, while extensive exposure induced a loss of vendibility due to protein aggregation. PRACTICAL APPLICATION: In this study, we demonstrated for the first time, that plasma species reacted with soybean proteins, resulting in spatial structural changes which are closely related with protein functionality and allergenicity. ACP interacts with macromolecules in aqueous systems and thus can be an alternative and promising nonthermal approach in modifying soybean proteins, whereas the exact role of different processing parameters needs to be well-elaborated.

Electric field effects on proteins - Novel perspectives on food and potential health implications

Electric fields (EF) technologies have been establishing a solid position in emergent food processing and have seen as serious alternatives to traditional thermal processing. During the last decades, research has been devoted to elucidation of technological and safety issues but also fundamental aspects related with interaction of electric fields (EF) with important macromolecules, such as proteins. Proteins are building blocks for the development of functional networks that can encompass health benefits (i.e. nutritional and bioactive properties) but may be also linked with adverse effects such as neurodegenerative diseases (amyloid fibrils) and immunological responses. The biological function of a protein depends on its tridimensional structure/conformation, and latest research evidences that EF can promote disturbances on protein conformation, change their unfolding mechanisms, aggregation and interaction patterns. This review aims at bringing together these recent findings as well as providing novel perspectives about how EF can shape the behavior of proteins towards the development of innovative foods, aiming at consumers' health and wellbeing.

A Snapshot on Food Allergies: A Case Study on Edible Flowers

This perspective study addresses the main causes of adverse reactions to foods in humans, by taking into account the main allergic reactions that may occur as a result of food ingestion, as well the main allergens present in food and how their allergenicity change as a result of food preparation. In addition, European legislation on food labeling and novel foods was taken into account. The case study of this perspective is on the potential allergenicity of edible flowers as well as evidence of phytochemistry and toxic compounds and the risk associated with their ingestion. Regarding edible flowers, a key issue to address is if they are safe to consume or not. In the framework of the project “Innovative activities for the development of the cross-border supply chain of the edible flower” (ANTEA), we considered 62 different species and varieties of edible flowers. The results obtained by consulting two databases on allergens, COMPRISE and Allergen Nomenclature, marked two alerts for two species of edible flowers selected in the project. Moreover, based on edible flower consumption, about ten grams per serving, and on their protein content, we can also state that the risk of allergic reactions due to edible flower ingestion is very low.

Are Physicochemical Properties Shaping the Allergenic Potency of Plant Allergens?

This review searched for published evidence that could explain how different physicochemical properties impact on the allergenicity of food proteins and if their effects would follow specific patterns among distinct protein families. Owing to the amount and complexity of the collected information, this literature overview was divided in two articles, the current one dedicated to protein families of plant allergens and a second one focused on animal allergens. Our extensive analysis of the available literature revealed that physicochemical characteristics had consistent effects on protein allergenicity for allergens belonging to the same protein family. For example, protein aggregation contributes to increased allergenicity of 2S albumins, while for legumins and cereal prolamins, the same phenomenon leads to a reduction. Molecular stability, related to structural resistance to heat and proteolysis, was identified as the most common feature promoting plant protein allergenicity, although it fails to explain the potency of some unstable allergens (e.g. pollen-related food allergens). Furthermore, data on physicochemical characteristics translating into clinical effects are limited, mainly because most studies are focused on in vitro IgE binding. Clinical data assessing how these parameters affect the development and clinical manifestation of allergies is minimal, with only few reports evaluating the sensitising capacity of modified proteins (addressing different physicochemical properties) in murine allergy models. In vivo testing of modified pure proteins by SPT or DBPCFC is scarce. At this stage, a systematic approach to link the physicochemical properties with clinical plant allergenicity in real-life scenarios is still missing.