Characterization of physicochemical and immunogenic properties of allergenic proteins altered by food processing:a review

Food allergens are mainly naturally-occurring proteins with immunoglobulin E(IgE)-binding epitopes.Understanding the structural and immunogenic characteristics of allergenic proteins is essential in assessing whether and how food processing techniques reduce allergenicity.We here discuss the impacts of food processing technologies on the modification of physicochemical,structural,and immunogenic properties of allergenic proteins.Detection techniques for characterizing changes in these properties of food allergens are summarized.Food processing helps to reduce allergenicity by aggregating or denaturing proteins,which masks,modifies,or destroys antigenic epitopes,whereas,it cannot eliminate allergenicity completely,and sometimes even improves allergenicity by exposing new epitopes.Moreover,most food processing techniques have been tested on purified food allergens rather than food products due to potential interference of other food components.We provide guidance for further development of processing operations that can decrease the allergenicity of allergenic food proteins without negatively impacting the nutritional profile.

The detection and regulation advances of food allergens

Food allergy has become an important food quality and safety issue,posing a challenge to the food industry and affecting consumer health.On the one hand,from the perspective of food processing industry,the diversity of food raw material ingredients,exogenous additives,and processing forms make the presence of allergens in modern food processing more complex.In addition,due to the lack of allergen identification,effective detection and allergenicity evaluation systems,there are serious deficiencies in the current theories and techniques for food allergen screening and detection,tracking and prediction,intervention and control;On the other hand,from the perspective of public health,meeting consumers'right to know whether there are raw materials containing food allergens in processed foods,and improving the credibility of government and people's satisfaction have become urgent matters;In addition,as people come into contact with more and more new borne novel foods,the probability of food allergy is also increasing.The food safety and health problems induced by increasingly complex,widespread and severe food allergy are difficult to avoid.In view of this,in response to the increasingly serious food allergy issues,this paper introduced the detection methods of food allergens,summarized the reduction and control techniques of food allergens,and elaborated hypoallergenic foods,which aims to provide the basis for preventing and controlling food allergy and ensuring the physical health of food allergy patients.

Allergenicity mitigation strategies of seafood allergens for hypoallergen

Introduction Seafood is a widely consumed and nutritionally rich food source,but it ranks among the top allergens,with shellfish and fish being major triggers of allergic reactions.These reactions,primarily caused by proteins such as tropomyosin(TM)in shellfish and parvalbumin(PV)in fish,can lead to life-threatening anaphylaxis in susceptible individuals.The development of hypoallergenic seafood is becoming increasingly important to provide safe alternatives for those with seafood allergies.This comment reviews recent advances in allergenicity mitigation strategies,highlighting the progress made and future potential in producing hypoallergenic seafood products.

Cross-reactivity between aeroallergens and food allergens

In patients with respiratory allergy,cross-reactivity between aeroallergens and foods may induce food allergy,symptoms ranging from oral allergy syndrome to severe anaphylaxis.Clinical entities due to Ig E sensitization to cross-reactive aeroallergen and food allergen components are described for many sources of plant origin(pollen-food syndromes and associations,such as birch-apple,cypress-peach and celery-mugwortspice syndromes,and mugwort-peach,mugwortchamomile,mugwort-mustard,ragweed-melon-banana,goosefoot-melon associations),fungal origin(Alternariaspinach syndrome),and invertebrate,mammalian or avian origin(mite-shrimp,cat-pork,and bird-egg syndromes).Clinical cases of allergic reactions to ingestion of food products containing pollen grains of specific plants,in patients with respiratory allergy to Asteraceae pollen,especially mugwort and ragweed,are also mentioned,for honey,royal jelly and bee polen dietary supplements,along with allergic reactions to foods contaminated with mites or fungi in patients with respiratory allergy to these aeroallergens.Medical history and diagnosis approach may be guided by the knowledge about the diverse cross-reacting allergens involved,and by the understanding of these clinical entities which may vary significantly or may be overlapping.The association between primary Ig E sensitization with respiratory symptoms to inhaled allergens and food allergy due to cross-reactive allergen components is important to assess in allergy practice.The use of molecular-based diagnosis improves the understanding of clinically relevant Ig E sensitization to cross-reactive allergen components from aeroallergen sources and foods.

Studies on BN rats model to determine the potential allergenicity of proteins from genetically modified foods

AIM： To develop a Brown Norway （BN） rat model to determine the potential allergenicity of novel proteins in genetically modified food. METHODS： The allergenicity of different proteins were compared, including ovalbumin （OVA）, a potent respiratory and food allergen, bovine serum albumin （BSA）, a protein that is considered to have a lesser allergenic potential, and potato acid phosphatase （PAP）, a non-allergenic protein when administered to BN rats via different routes of exposure （intraperitoneally or by gavage）. IgG and IgE antibody responses were determined by ELISA and PEA, respectively. An immunoassay kit was used to determine the plasma histamine level. In addition, possible systemic effect of allergens was investigated by monitoring blood pressure. RESULTS： OVA provoked very vigorous protein-specific IgG and IgE responses, low grade protein-specific IgG and IgE responses were elicited by BSA, while by neither route did PAP elicit anything. In either routes of exposure, plasma histamine level in BN rats sensitized with OVA was higher than that of BSA or PAP. In addition, an oral challenge with BSA and PAP did not induce any effect on blood pressure, while a temporary drop in systolic blood pressure in few animals of each routes of exposure was found by an oral challenge with OVA. CONCLUSION： BN rat model might be a useful and predictive animal model to study the potential allergenicity of novel food proteins.

Ultrathin metal-organic framework nanosheets (Cu-TCPP)-based isothermal nucleic acid amplification for food allergen detection

The rapid and accurate detection of peanuts and soybeans allergen is important to the food safety. In this study, Cu-TCPP nanosheet, a kind of ultra-thin metal-organic framework(MOF)was synthesized and applied in loop-mediated isothermal amplification(named Cu-TCPP@LAMP), which can inhibit the non-specific amplification by absorbing and precise temperature releasing of single primer. As thus, Cu-TCPP@LAMP can achieve high sensitivity and specific amplification of the target gene. As a result, peanut and soybean allergens genes contained in food were successfully detected with a favorable detection sensitivity(5 ng/μL for peanuts and 10 ng/μL for soybeans)and reliable repeatability(The coefficient of variation was 3.38% for peanuts and 3.33% for soybeans). Moreover, the established method was utilized for detection of several commercial products, and had a high consistency with the standard method. Apart from food allergens, this novel assay can be widely used in other areas, such as pathogen detection, tumor nucleic acid detection and so on.

Synchronously Detecting Allergenic Ingredients of Peanut and Sesame in Food by Real-time Fluorescent PCR

Peanut,sesame and other raw materials of food are allergens for special populations.In this study,specific primers and TaqMan probes labeled by different fluorescences were designed targeting Ara h 2 gene of peanut and Ses i 1 gene of sesame.After the optimization of reaction conditions,a real-time fluorescent PCR method was established for simultaneous detection of allergenic ingredients of peanut and sesame in food.Genomic DNA samples of peanut,sesame,rice,wheat,barley,soybean,celery,maize,potato,tomato,walnut,groundnut in shell,cashew nut,sunflower seed,almond,apple,pear and strawberry,pork,beef,mutton and fish were used as templates for PCR amplification with deionized water as negative control template.Results indicated that the established real-time fluorescent PCR method could specifically identify allergenic ingredients of peanut and sesame simultaneously.Sensitivity test showed that the minimum detection limit of this method was 0.01%.Therefore,the established real-time fluorescent PCR method is a specific,sensitive and effective assay for simultaneously detecting allergenic ingredients of peanut and sesame in food.

A Possible Hypoallergenic Cereal in Wheat Food Allergy and Baker’s Asthma

Background: Wheat is a potent allergen source and is one of the causes of baker’s asthma and food allergy. The best strategy for managing food hypersensitivity involves strict avoidance of the trigger. However, wheat is quite difficult to avoid. Several alternative strategies for the treatment of food allergy are under study. Spelt is a possible hypoallergenic crop that may be tried in patients with wheat allergy. Methods: We have evaluated the allergenic IgE hypersensitivity mediated by spelt in wheat allergic patients. Overall, 66 patients who suffered from baker’s asthma or food allergy (45 males and 21 females, mean age 28.6 ± 12.9 years) were included. We have also compared its reactivity with standard- ized extracts from wheat and with purified non-specific lipid transfer proteins from wheat (Tri a 14) and from peach (Pru p 3). Immunodetection with spelt and common bread wheat extracts (Triticum aestivum, cultivar Astral) was per- formed. Fresh wheat and spelt grain extracts were used both for oral and bronchial challenge and skin tests. Specific IgE detection to different cereals was performed using the Immuno CAP System (Phadia, Uppsala, Sweden). The bronchial challenge was positive with wheat Astral in 44 (67%) patients, all of them suffered from asthma. Thirteen (29.54%) of these 44 patients had negative the challenge with spelt. The oral challenge with wheat Astral was positive in 22 (33%) patients with wheat food allergy, and the same test was positive in only in 6 of them with spelt (27.3%). The diagnostic yield (sensitivity, specificity and predictive values) of routine tests in determining spelt allergy by specific positive challenge responses was determined. Prick tests for spelt versus positive challenge tests had a good sensitivity (94%, 86.5 - 99.4;95%CI) and specificity (86%, 84 - 90;95% CI) for the diagnosis of spelt allergy. Immunodetection detected minor differences among different extracts. Conclusion: In summary, the prick test and bronchial and oral challenges both efficiently detected sensitization to spelt and their levels were related to more severe clinical profiles, but the wheal area was significantly lower with spelt (p 0.001) and the percentage of positive challenge tests decreased. Our results suggest that spelt is an old crop that may be tried in patients with wheat allergy.

IgE Reactivity of Potential Allergens from the Swimming Crab Portunus trituberculatus and the Research of ELISA Reagent for Detecting Crab Food Anaphylaxis

Crustacean is one of the major allergic foods.It is of great significance to identify more crab allergens and research the detection methods for crab food anaphylaxis.In this study,IgE reactivity to three recombinant proteins from Portunus trituberculatus,including tropomyosin(rPtTM),myosin light chain(rPtMLC),and pancreatic lipase(rPtPL),were detected by enzyme-linked im-munosorbent assay(ELISA).The expressions of tropomyosin(TM)in various tissues of P.trituberculatus were detected by Western blot(WB).Furthermore,microplates were coated with rPtTM and the ELISA conditions were optimized.The cut-off value was deter-mined by the receiver operating characteristic(ROC)curve.Among 51 crab-allergic sera,21(41.2%)showed positive IgE to rPtTM.Other 70 crab-allergic sera more frequently recognized rPtPL(9/70;12.9%),followed by rPtMLC(1/70;1.4%).WB results showed that TM was mainly expressed in the muscle,followed by the heart and a small amount in gills and the testis.The optimal results showed that the coating condition of rPtTM was 50 ng per well with coating for 3 h at 37℃.The optimal blocking condition was 1.2%BSA with blocking for 3 h at 37℃,and the optimal dilution of the second antibody was 1:1500.The ROC curve showed that the ELISA reagent had high sensitivity(83.52%)and specificity(98.00%)when the cut-off value was 0.45.All results indicated that tropomyosin is the major allergen of P.trituberculatus,and myosin light chain and pancreatic lipase are the potential allergens.Addi-tionally,the ELISA reagent developed with the rPtTM was feasible for laboratory detection of crab anaphylaxis.

Determination of egg and milk allergen in food products by liquid chromatography-tandem mass spectrometry based on signature peptides and isotope-labeled internal standard

The aim of this work was to develop a liquid chromatography-tandem mass spectrometry method for the determination of milk allergen and egg allergen in food products.Signature peptides GGLEPINFQTAADQAR,VGINYWLAHK,VLVLDTDYK,FFVAPFPEVFGK,and NAVPITPTLNR were confirmed and synthesized as the quantitative peptide of ovalbumin,α-lactalbumin,β-lactoglobulin,α_(S1)-casein andα_(S2)-casein,the relative isotope-labeled internal standards were used in the quantitative analysis.Linear range was in the range of0.5-5000.0 nmol/L for egg and milk allergen in bread,cake,cookie,rice crust and wheat flour samples with free from egg and milk,the limits of detection of milk allergens and egg allergen were in the range between0.94 mg/100 g and 56.71 mg/100 g,limits of quantification of milk allergens and egg allergen were in the range between 2.36 mg/100 g and 141.78 mg/100 g.The recoveries ranged from 76.7%to 122.8%,the relative standard deviations were in the range of 1.60%-15.60%.The developed method has been successfully used for the detection of egg and milk allergen in various food samples.

Food Allergens and Food Safety： A Global Perspective with Respect to Codex Alimentarius

Over the last two decades, food allergens are being recognized as one of the food hazards. This serious food safety issue is being addressed in different countries not only in terms of their biological and clinical characteristics, but also in terms of various standards of allergen management in food industries. This abnormal immune response caused by food allergens affects the quality of life especially in children and influences their overall health and retards normal growth, along with they suffer from ailments like eating disorders, depression, sometimes even death which is the most adverse impact of food allergy. Every country has their own set of guidelines to deal with the food allergens especially developed countries, food allergen guidelines is not well documented in developing countries. FAO/WHO is providing assistance to developing countries in strengthening their food safety guidelines. The Codex Alimentarius was formulated by the two organizations FAO/WHO in the year 1960; it is a collection of food standards in a integrated, codified style, together with associated material such as codes of hygiene and good manufacturing practices that should be followed by industries during various production stages of a food item. In both developed and developing nations, the Food Chemical Codex or the Codex Alimentarius aims to protect public health and implement fair trade practises for the trading of food items.

Concerns arise: wheat allergy risk in pre-packaged food products from China

Understanding and monitoring the cross-contamination of food allergens is crucial for safeguarding public health and ensuring food safety.Food allergen risk assessment,derived from classical toxicological principles,can identify and quantify the risk of allergies.This study aimed to investigate the risk of wheat allergic reactions to prepackaged foods from China through the utilization of food allergen risk assessment.A total of 575 products have been surveyed,wheat/gluten,milk and egg were major allergens labelled on products.According to voluntary incidental trace allergen labelling 3.0(VITAL®3.0)program,the number of products belonged to Action Level 2 were 303.Integration of precautionary allergen labeling(PAL)analysis indicated that 9.57%products would pose a potential risk to wheat allergic individuals.The probabilistic risk assessment results suggest that 7984 allergic reactions may arise among wheat-allergic consumers during 10000 eating occasions due to the consumption of pre-packaged food products with incorrect wheat-related allergen labelling.This study demonstrated that a risk assessment-based approach can support the guidance of allergen labelling and management of food allergen for pre-packaged food products,providing protection for allergic individuals in food consumption and for food manufacturers in food production and trade.

Major allergens in 8 types of allergenic foods and allergen detection techniques

In recent years,the prevalence of allergens in food warning notices,both domestically and internationally,has become the second leading concern after microbial contamination.Among the various factors that threaten human health reported by the World Health Organization,food allergy ranks fourth,and food allergy has become a global security problem.As of now,no definitive treatment for food allergies exists,making the avoidance of allergen-containing foods the most effective prevention method.Consequently,labeling foods with allergen information serves as a crucial warning for allergic populations.Moreover,to enhance comprehension of food allergies,this article provides a brief overview of their definition and sensitization mechanisms.The main focus lies in highlighting the structure of primary allergens found in eight commonly allergenic foods and the resulting clinical symptoms they cause.Additionally,a summary of commonly employed allergen detection techniques is presented,with an analysis of their principles,advantages,and limitations.Looking ahead,the integration of diverse technological approaches to establish an efficient,accurate,and affordable allergen detection method remains a significant trend.This article has certain reference value for understanding the direction of food allergies.

Recent advances in the study of epitopes,allergens and immunologic cross-reactivity of edible mango

Mango(Mangifera indica L.)is a tropical fruit that is widely consumed as both fresh fruits and processed products around the world.The high incidence of mango allergy,on the other hand,has sparked widespread concern.Therefore,a summary and analysis of the current status and issues in mango allergen research can guide in-depth study on the mechanism of mango allergy and reveal effective desensitization methods.We described the incidence of fruit allergy,as well as the mechanism and clinical symptoms of mango allergy,in this review.We also looked into the structural properties of mango allergens,the effect of processing methods on mango allergens,prediction methods for mango allergen epitopes,and the current state of research on mango cross-reactive allergens and preventive measures.Finally,the research directions and ideas for the future are proposed and discussed.

Overview of allergenic risk of novel foods

The reported cases of food allergies are steadily increasing.With the invention of more novel foods,new and unfamiliar allergens are being introduced into our diets,which raises concerns about the potential risk of novel food allergies.The purpose of this review is to assess the allergenic risks associated with novel food components,strategies for assessing risk in relation to novel food allergens,and current regulations for managing food allergens in novel food products.

Potential of high hydrostatic pressure in reducing the allergenicity of seafood

Seafood,as a primary high-quality protein source,plays an increasingly vital role in diets around the world,while seafood allergy is a worldwide health problem that affects the quality of life and may even threaten lives.High hydrostatic pressure(HHP),a novel non-thermal processing technology,shows the unique potential in alleviating seafood allergenicity.This comment provides a brief introduction of potential of high hydrostatic pressure in reducing the allergenicity of seafood.

Adulteration detection of plant protein beverages by UPLC-MS/MS based on signature peptide of allergen

Plant protein beverage adulteration occurs frequently,which may cause health problems for consumers due to the hidden allergens.Hence,a novel method was developed for authentication by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).Almond,peanut,walnut and soybean were hydrolyzed,followed by separation by NanoLC-Triple TOF MS.The obtained fingerprints were identified by ProteinPilotTM combined with Uniprot,and 16 signature peptides were selected.Afterwards,plant protein beverages treated by trypsin hydrolysis were analyzed with UPLC-MS/MS.This method showed a good linear relationship with R2>0.99403.The limit of quantification(LOQ)were 0.015,0.01,0.5 and 0.05 g/L for almond,peanut,walnut and soybean,respectively.Mean recoveries ranged from 84.77%to 110.44%with RSDs<15%.The developed method was successfully applied to the adulteration detection of 31 plant protein beverages to reveal adulteration and false labeling.Conclusively,this method could provide technical support for authentication of plant protein beverages to protect the rights and health of consumers.

Dietary polyphenols reduced the allergenicity ofβ-lactoglobulin via non-covalent interactions:a study on the structure-allergenicity relationship

Studies showed that complexation of polyphenols with milk allergens reduced their immunogenic potential.However,the relationship between structures of polyphenols and their hypoallergenic effects on milk allergens in association with physiological and conformational changes of the complexes remain unclear.In this study,polyphenols from eight botanical sources were extracted to prepare non-covalent complexes withβ-lactoglobulin(β-LG),a major allergen in milk.The dominant phenolic compounds bound toβ-LG with a diminished allergenicity were identified to investigate their respective role on the structural and allergenic properties ofβ-LG.Extracts from Vaccinium fruits and black soybeans were found to have great inhibitory effects on the IgE-and IgG-binding abilities ofβ-LG.Among the fourteen structure-related phenolic compounds,flavonoids and tannins with larger MWs and multi-hydroxyl substituents,notably rutin,EGCG,and ellagitannins were more potent to elicit changes on the conformational structures ofβ-LG to decrease the allergenicity of complexedβ-LG.Correlation analysis further demonstrated that a destabilized secondary structure and protein depolymerization caused by polyphenol-binding were closely related to the allergenicity property of formed complexes.This study provides insights into the understanding of structure-allergenicity relationship ofβ-LG-polyphenol interactions and would benefit the development of polyphenol-fortified matrices with hypoallergenic potential.

Allergen degradation of bee pollen by lactic acid bacteria fermentation and its alleviatory effects on allergic reactions in BALB/c mice

Food allergy as a global health problem threatens food industry.Bee pollen(BP)is a typical food with allergenic potentials,although it performs various nutritional/pharmacological functions to humans.In this study,lactic acid bacteria(LAB)were used to ferment Brassica napus BP for alleviating its allergenicity.Four novel allergens(glutaredoxin,oleosin-B2,catalase and lipase)were identified with significant decreases in LAB-fermented BP(FBP)than natural BP by proteomics.Meanwhile,metabolomics analysis showed significant increases of 28 characteristic oligopeptides and amino acids in FBP versus BP,indicating the degradation of LAB on allergens.Moreover,FBP showed alleviatory effects in BALB/c mice,which relieved pathological symptoms and lowered production of allergic mediators.Microbial high-throughput sequencing analysis showed that FBP could regulate gut microbiota and metabolism to strengthen immunity,which were closely correlated with the alleviation of allergic reactivity.These findings could contribute to the development and utilization of hypoallergenic BP products.

Validation of Molecular Detection Methods for Gluten Allergens in Infant Formula

[Objectives]To verify the specificity,sensitivity,precision and negative-positive deviation of the foodproof gluten component de-tection kit for the detection of gluten allergens in milk powder matrix,and to establish a real-time fluorescent PCR legal method for the detec-tion of gluten allergens in milk powder.[Methods]The specificity,sensitivity,precision and negative-positive deviation of the detection method of foodproof gluten component detection kit(PCR-probe method)were verified by artificially adding different concentrations of wheat bran and extracting sample DNA by kit method,and applied to sample detection.[Results] The specific detection results of two kinds of milk powder with wheat bran and buckwheat added showed that the foodproof gluten component detection kit(PCR-probe method)had good speci-ficity for wheat gluten.The results of artificially added wheat bran positive samples showed that the false positive rate and false negative rate of the kit in the milk powder matrix were O,and the sensitivity and precision were high.[Conclusions]The kit is simple to operate and has high accuracy,which is suitable for the detection of gluten allergen components in milk powder.