Methods for allergen analysis in food: a review

Study on the induced polymeric protein aggregation and immunoreactivity in biscuits enriched with peanut flour

This work deals with the study on the protein extractability of biscuits incurring different percentages of roasted peanut flour. The presence of two different flours influenced the rate of protein aggregation and protein extractability, according to the percentage of roasted peanut flour added to the formulation and assessing these features by testing the use of two buffers. Results showed that gluten network arrangement of biscuits was influenced by the flours mixture besides the baking, with possible different protein organizations. Protein extractability was affected, underlining a higher content of protein aggregates at high molecular weight especially with the addition of 20% of peanut flour, characterized by hydrophobic and reducible covalent bonds, as suggested by the higher extractability obtained with the buffer with chaotropic and reducing agents. These results suggested a possible induced supramolecular protein organization in these products, which could affect the immunoreactivity of the main allergens occurred in the formulation.

Mismanagement and poor transparency in the European processed seafood supply revealed by DNA metabarcoding

In the global processed seafood industry, disparate actors play different roles along the supply chain, creating multiple opportunities for mistakes, malpractice, and fraud. As a consequence, consumers may be exposed to non-authentic products, which hinder informed purchasing decisions and broader efforts to improve trade transparency and sustainability. Here, we characterised the taxonomic composition of 62 processed seafood products in Italian, British and Albanian retailers, purposefully obtained from different supply routes, using multiple DNA metabarcoding markers. By combining molecular results with metadata reported on labels, we revealed patterns of mislabelling in 24 products (39%) across sampling regions, denoting lack of transparency of processed seafood products based on resources sourced from either Europe or globally. We show that the accuracy of label claims and the mis-represented and underestimated levels of traded biodiversity are largely determined by the management of raw material by global processors. Our study shows that DNA metabarcoding is a powerful and novel authentication tool that is mature for application at different stages of the seafood supply chain to protect consumers and improve the sustainable management of fish stocks.

Effects of genetic diversity on the allergenicity of peanut (Arachis hypogaea) proteins: identification of the hypoallergenic accessions using BALB/c mice model and in silico analysis of Ara h 3 allergen cross-reactivity

This study investigated the effects of genetic diversity in the allergenicity of peanut and assessed the allergenic capacity of six Arachis hypogaea accessions using a Balb/c mouse model. It also explored potential cross-reactivities between Ara h 3 (peanut allergen) and Gly m (soybean allergen) using computational tools. Female Balb/c mice were injected with peanut protein extracts and alum. Serum-specific antibodies (IgE, IgGt, IgG1, IgG2a) were measured using ELISA, and allergic protein profiles were examined via western blot. Structural homology, B cell epitopes, and molecular interactions between Ara h 3 and Gly m with human IgE were also investigated. The mice developed high sIgE and sIgG1 responses, with antibodies recognizing 19 bands on western blot. Notably, Saharan accessions showed unique features such as no bands on western blot profiles, reduced anaphylactic symptoms, lower IgE titers, and less intestinal tissue damage. Molecular docking results suggest significant cross-allergenicity, supported by allergenicity predictions and structural homology analysis. This comprehensive analysis provides insights into shared epitopes, potential competition for binding sites, and molecular dynamics of cross-reactive responses, enhancing understanding of food allergen interactions. The study recommends using Algerian Sahara peanut accessions in breeding, genomics studies, and industry for safer peanut options for individuals with allergies. SIGNIFICANCE: The significance of this study lies in its contribution to addressing a major public health issue: peanut allergy, which represents a significant cause of anaphylaxis affecting numerous individuals and families worldwide. By exploring the genetic diversity of peanut proteins and identifying hypoallergenic accessions through experimental and computational approaches, this research offers valuable insights for mitigating allergic reactions. The findings highlight that certain accessions from the Saharan region exhibit reduced allergenicity, resulting in attenuated anaphylactic symptoms, lower IgE levels, and reduced intestinal damage in murine models. Furthermore, the study's in silico analysis sheds light on the issue of cross-reactivity between peanut and soybean allergens, providing crucial information for understanding allergen interactions at the molecular level. Overall, this research contributes to advancing knowledge in the field of food allergen research and has practical implications for improving the quality of life for individuals allergic to peanuts, particularly through the selection of safer peanut varieties and their cultivation.

Sesame Detection in Food Using DNA-Functionalized Gold Nanoparticles: A Sensitive, Rapid, and Cost-Effective Colorimetric Approach

Food safety control is a key issue in the food and agriculture industries. For such purposes, developing miniaturized analytical methods is critical for enabling the rapid and sensitive detection of food supplements, allergens, and pollutants. Here, a novel bioanalytical methodology based on DNA-functionalized gold nanoparticles (AuNPs) and colorimetric detection was developed to detect the presence of sesame (a major allergen) through sesame seed DNA as a target, in food samples. The presence of sesame DNA induces controlled nanoparticle aggregation/desegregation, resulting in a color change (from blue to red) proportional to sesame DNA concentration. The incorporation of multicomponent nucleic acid enzymes (MNAzymes) in this strategy has been carried out to perform an isothermal signal amplification strategy to improve the sensitivity of detection. Also, open-source software for color analysis was used to ensure an unbiased visual color-change detection, enhancing detection accuracy and sensitivity and opening the possibility of performing a simple and decentralized analyte detection. The method successfully detected the presence of sesame DNA in sesame seed, sesame oil, olive oil, and sunflower oil. In brief, the developed approach constitutes a simple and affordable alternative to perform a highly sensitive detection of DNA in food without complex methodologies or the requirement of expensive instrumentation.

Recent advance in sesame allergens: Influence of food processing and their detection methods

Sesame (Sesamum indicum L.) is a valuable oilseed crop with numerous nutritional benefits containing a diverse range of bioactive compounds. However, sesame is also considered an allergenic food that triggers various mild to severe adverse reactions (e.g., anaphylaxis). Strict dietary avoidance of sesame components is the best option to protect the sensitized consumers. Sesame or sesame-derived foods are always consumed after certain food processing operations, which would cause a considerable impact on the structure of sesame proteins, changing their sensitization capacity and detectability. In the review, the molecular structure properties, and immunological characteristics of the sesame allergens were described. Meanwhile, the influence of food processing techniques on sesame proteins and the relevant detection techniques used for the sesame allergens quantification are also emphasized critically. Hopefully, this review could provide valuable insight into the development and management for the new "Big Eight" sesame allergen in food industry.

Clinical Effect of Thioglycosides Extracted from White Mustard on Dental Plaque and Gingivitis: Randomized, Single-Blinded Clinical Trial

The antibacterial and anti-inflammatory effect of thioglycosides has already been established. This study investigates the effects of thioglycosides extracted from white mustard, specifically the "Bamberka" variety, in the context of oral hygiene. The aim of the study is to clarify an evidence-based link between the documented antibacterial and anti-inflammatory effects attributed to thioglycosides and their practical application in oral care. A randomized, single-blinded (patient-blinded) clinical study was performed on 66 patients using mustard-based toothpaste for oral hygiene. The patients were examined at baseline and after 6 and 12 months. The values of the Approximal Plaque Index (API), the Plaque Index (PI), and Bleeding on probing (BOP) were taken into consideration. The results show a significant reduction in plaque accumulation, especially after 6 months of using mustard-based toothpaste in all examined parameters. This suggests that thioglycosides from mustard contribute to a considerable decrease in dental plaque accumulation, confirming their potential in natural oral care solutions, which is indicated in the main conclusions or interpretations.

Effect of lactic acid bacteria fermentation on cow milk allergenicity and antigenicity: A review

Cow milk is a major allergenic food. The potential prevention and treatment effects of lactic acid bacteria (LAB)-fermented dairy products on allergic symptoms have garnered considerable attention. Cow milk allergy (CMA) is mainly attributed to extracellular and/or cell envelope proteolytic enzymes with hydrolysis specificity. Numerous studies have demonstrated that LAB prevents the risk of allergies by modulating the development and regulation of the host immune system. Specifically, LAB and its effectors can enhance intestinal barrier function and affect immune cells by interfering with humoral and cellular immunity. Fermentation hydrolysis of allergenic epitopes is considered the main mechanism of reducing CMA. This article reviews the linear epitopes of allergens in cow milk and the effect of LAB on these allergens and provides insight into the means of predicting allergenic epitopes by conventional laboratory analysis methods combined with molecular simulation. Although LAB can reduce CMA in several ways, the mechanism of action remains partially clarified. Therefore, this review additionally attempts to summarize the main mechanism of LAB fermentation to provide guidance for establishing an effective preventive and treatment method for CMA and serve as a reference for the screening, research, and application of LAB-based intervention.

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.

Study on the reduction of Tartary buckwheat allergenicity during Pediococcus pentosaceus fermentation by HPLC-MS/MS analysis

Tartary buckwheat contains more valuable nutrients than common buckwheat, but it also contains allergenic proteins that induce allergic reactions through an IgE-mediated response. Our study demonstrated that fermentation by Pediococcus pentosaceus degrades allergenic proteins in Tartary buckwheat, as confirmed by HPLC-MS/MS analysis of polypeptides. Our results showed significant degradation of the protein after 16 h of Pediococcus pentosaceus fermentation (PP16), leading to a reduction in IgE-binding activity. Comparison with unfermented Tartary buckwheat (UTB) peptides yielded 2042 fragments, of which 756 fragments associated with allergenic proteins were upregulated. Among them, the expression of 213 fragments was reduced by 71.83%. By performing bioactivity prediction on potential allergenic peptide fragments, we identified six peptide fragments derived from Fagt 1, potentially contributing to the residual allergenicity in PP16. These suggest that Pediococcus pentosaceus fermentation can effectively destroy allergen epitopes and mitigate the allergenicity of Tartary buckwheat.

Aquatic food animals in the United States: Status quo and challenges

This review summarizes (1) the U.S. status quo for aquatic food animal production and marketing; (2) major food safety and quality issues/concerns for aquatic food animals in the United States, including fish misbranding, finfish/shellfish allergies, pathogens, toxins and harmful residues, microplastics, and genetically engineered salmon; and (3) various U.S. regulations, guidances, and detection methods for the surveillance of fishery products. Overall, fish misbranding is the biggest challenge in the United States due to the relatively low inspection rate. In addition, due to the regulatory differences among countries, illegal animal drugs and/or pesticide residues might also be identified in imported aquatic food animals. Future regulatory and research directions could focus on further strengthening international cooperation, enhancing aquatic food animal inspection, and developing reliable, sensitive, and highly efficient detection methods.

Biological activity and processing technologies of edible insects: a review

The burgeoning global population growth has raised concerns regarding the expected increase in the demand for food, which could be partially tackled by identifying novel food sources. To this end, edible insects have recently attracted research interest. Several technologies for utilizing edible insect-derived proteins have been introduced; however, research into their functional utilization is insufficient. Herein, we reviewed the relevant literature on the importance of insects as food sources, extraction of edible insects, the nutritional value of insects, biological activities of components, and their applications in food industries. We summarized the studies primarily focused on the functional utilization of edible insects, suggesting that for successful incorporation and growth of edible insects in food and pharmaceutical industries, strategies to improve the extraction methods are required to explore the biological activity of edible insects. Furthermore, the awareness of edible insects with a focus on their allergens warrants consideration.

Development of triplex PCR for simultaneous detection of soybean and wheat

There is a constant demand for an effective detection method of major allergens, such as soybean (Glycine max) and wheat (Triticum aestivum). In this study, a triplex polymerase chain reaction (PCR) method was developed for rapid detection of soybean and wheat in processed food products. This triplex PCR contains soybean- and wheat-specific primer pairs and universal primer pair for plant species. Each primer pair was applied to 22 different plant species and showed high specificity with no amplification in non-target species. The sensitivity of triplex PCR for soybean and wheat was 10 pg. The detection limit for soybean and wheat in pea mixture was 0.1%. The developed triplex PCR showed high sensitivity and specificity and was applied to 21 different commercial products. The results were in accordance with the label. Thus, this method is expected to be useful in preventing allergy-related issues via accurate labeling of major allergens in food.

Food additives: From functions to analytical methods

Food additives refer to all kinds of trace substances used in food or food processing to preserve flavor or enhance food taste, appearance, or other qualities. At present, artificial synthetic food additives have gradually replaced the natural food additives and many problems related to food additives, involving the abuse of food additives, excessive additives or even toxic additives. Obviously, food additives can bring people great sensory enjoyment and commercial convenience, but they may also cause potential risks to human health. So, it is of high significance to conduct quantitative analysis on the content of food additives. According to their functions and the regulatory requirements of food additives, this review starts from the classification and structures of various food additives involving colorants, preservatives, antioxidants, sweeteners, emulsifiers, stabilizers, thickeners, gelling agents. It then summarizes and discusses analytical methods for quantification of food additives including modern immunoassays and other biotechnological methods. The proposed review aspires to fill in the knowledge gap of food additives between academia and industry by covering all kinds of analytical methods for quantifying food additives.

Development of a simplified, sensitive, and accurate LC-MS/MS method for peanut quantification in wheat flour-based dry matrices

In this study, an ELISA-based method was observed to overestimate quantification of peanut in three wheat flour-based dry matrices (both raw and cooked). A reliable method using liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed to quantify peanut accurately in these matrices. This method simplified both sample preparation and quantification compared with previous approaches, by digesting peanut proteins without reduction and alkylation and using Ara h 1 to build calibration curves. A significantly increased amount of peanut peptides was detected by heating the extracts. The sensitivity and linearity were superior to most commercial ELISA kits. The limit of quantification (LOQ) was 0.31 mg/kg total peanut in wheat flour and the linear range was between 0.3 and 40 mg/kg. This LC-MS/MS method could be applied as a confirmatory method for peanut allergen management when positive ELISA results raise suspicion of contamination.

Development of a Sandwich Enzyme-Linked Immunosorbent Assay for Detection and Quantification of Clam Residues in Food Products

Seafood is a frequent cause of allergic reactions to food globally. The presence of undeclared trace amounts of clam can cause allergic reactions in sensitive individuals. Limited tools are available to test food products for the presence of traces of clam. We report on the development of a sandwich ELISA that can detect and quantify clam protein in food. Antisera against a mix of two commercially important clam species, Atlantic Surf (Spisula solidissima) and ocean quahog (Arctica islandica), were raised in rabbit and sheep. A sandwich ELISA was constructed with this antisera, and sensitivity and specificity were evaluated. Also, model food products spiked with clam protein were analyzed to assess the performance of the ELISA. Comparison was made with a commercially available ELISA for crustacea. The lower limit of quantification of the sandwich ELISA is 2.5 ppm clam protein in food samples, allowing the detection of low amounts of clam that may trigger a reaction in clam allergic patients. The sandwich ELISA was highly specific with cross-reactivity only noted for other molluscan shellfish (mussel and scallop). Clam protein in tomato juice and potato cream soup was detected well with recoveries ranging from 65 to 74% and from 74 to 113%, respectively. However when potato cream soup was retorted, the recover fell to 20%, imposing the risk of underestimating the clam content of a food product. A commercially available crustacean ELISA test was not suitable to detect clam protein. The sandwich ELISA described here is suitable for detection and quantification of clam protein in food products. Care should be taken with food products that have been retorted as the results may be underestimated.

Novel bio-lab-on-a-tip for electrochemical glucose sensing in commercial beverages

The development of portable and user-friendly sensing platforms is a hot topic in the field of analytical chemistry. Among others, electroanalytical approaches exhibit a high amenability for reaching this purpose, i.e. the commercial strips for diabetes care are an obvious success. However, providing fully-integrated and reagent-free methods is always a leitmotiv. In this work, we evaluated the use of a disposable pipette tip, opportunely configured to demonstrate the first example of an electrochemical biosystem in a pipette tip, namely bio-lab-on-a-tip. The combination of a pipette tip, wire electrodes, enzyme, and cotton wool filter, allows the fabrication of a novel electroanalytical platform that does not need expertise-required tasks. To demonstrate the feasibility of this novel method, glucose is detected in beverages by means of chronoamperometry. The experimental setup, entirely built inside the pipette tip, is able to 1) block impurities/interferences from matrix, 2) load/release reagents for the bio-assay, 3) reduce the operating task to zero, and 4) perform electrochemical detection. With optimized experimental parameters, the bio-lab-on-a-tip is able to detect glucose linearly up to 10 mM with a detection limit of 170 μM. The effectiveness of the platform was confirmed by testing commercial beverages, e.g. Coca-Cola and Coca-Cola Zero, with high accuracy. In addition, the shelf-life of the novel device was evaluated, highlighting the role of cotton wool filter for providing a suitable environment for glucose oxidase stability. The novel concept can be easily generalized for further applications in the field of non-invasive clinical diagnostics and in-situ environmental monitoring.

Development and Application of Novel Chemiluminescence Immunoassays for Highly Sensitive Detection of Anisakis simplex Proteins in Thermally Processed Seafood

The third-stage larvae (L3) of Anisakis simplex are the most important source of hidden allergens in seafood products. However, there exist no commercial methods for detecting Anisakis proteins in food. Furthermore, only a few methods have been validated for the detection of A. simplex in thermally processed food. The aims of our study are (i) the development and validation of high-sensitivity chemiluminescent (CL) immunoassays for the detection of A. simplex proteins in processed seafood, (ii) and A. simplex antigen detection in common seafood products from Polish markets. We developed and validated CL sandwich ELISA (S-ELISA) and CL competitive ELISA (C-ELISA) methods for A. simplex proteins detection in food, with respective detection limits of 0.5 and 5 ng/mL. The usefulness of the assays for detecting A. simplex proteins in highly processed food was evaluated by examination of autoclaved canned fish spiked with A. simplex larvae (1–8 larvae/200 g). Commercial real-time PCR was unable to detect A. simplex in autoclaved samples at all levels of enrichment with Anisakis larvae. CL-S-ELISA was used to test various types of seafood products from Polish markets. Among all tested products (n = 259), 28% were positive. A. simplex antigens were found mostly (n = 39) in smoked fish products: mackerel, herring, cod, and hake. Other positive samples were found in marinated herrings, canned cod livers, canned mackerels, and surimi sticks. In tuna, Atlantic argentine, anchovy, sardine, sprat, and squid products, A. simplex antigens were not detected. This study provides novel effective tools for the detection of A. simplex proteins in processed food and highlights the potential allergic hazards for Anisakis-sensitized Polish consumers of seafood.

Commercial fish ELISA kits have a limited capacity to detect different fish species and their products

BACKGROUND

Fish is a major food and allergen source, requiring safety declarations on packages. Enzyme-linked immunosorbent assays (ELISAs) are often used to ensure that the product meets the required standards with regard to the presence of allergens. Over 1000 different fish species are traded and consumed worldwide, and they are increasingly provided by aquaculture. Up to 3% of the general population is at risk of sometimes fatal allergic reactions to fish, requiring strict avoidance of this commodity. The aim of this study is to evaluate the capacity of three commercially available ELISA tests to detect a wide variety of bony and cartilaginous fish and their products, which is essential to ensure reliable and safe food labeling.

RESULTS

The detection rates for 57 bony fish ranged from 26% to 61%. Common European and North American species, including carp, cod, and salmon species, demonstrated a higher detection rate than those from the Asia-Pacific region, including pangasius and several mackerel and tuna species. Among the 17 canned bony fish products, only 65% to 86% were detected, with tuna showing the lowest rate. None of the cartilaginous fish (n = 9), other vertebrates (n = 8), or shellfish (n = 5) were detected.

CONCLUSIONS

We demonstrated that three commercial fish ELISA kits had a limited capacity to detect fish and their products. The complexity of fish as a protein source that is increasingly utilized means that there is an urgent need for improved detection methods. This is crucial for the food industry to provide safe seafood products and comply with international legislation. © 2020 Society of Chemical Industry.

Peptide array-based inhibition ELISA for evaluating antigenicity in infant formulas

With increased awareness among consumers regarding food safety and security, food allergen control has become an indispensable requirement in the food industry. Although several methods for detecting allergens in food products are available, highly sensitive techniques are required. In this study, we developed a technique named as peptide array-based inhibition enzyme-linked immunosorbent assay (ELISA), Pep-iEIA, for evaluating antigenicity and detecting cow's milk antigen in infant formula products, using a peptide array consisting of a series of overlapping peptides found in allergenic milk proteins. Pep-iEIA was used to examine five cow's milk-based infant formulas with different degrees of hydrolyzation, and the assay offered both more sensitive detection and detailed analysis of remaining antigenic peptides in allergen compared to conventional ELISA. The antigenicity level of the allergenic peptides identified using Pep-iEIA was confirmed by surface plasmon resonance assay. We believe that Pep-iEIA will be highly useful for antigenicity evaluation of dairy products consumed by infants and patients with cow's milk allergy.

Development of a specific isothermal nucleic acid amplification for the rapid and sensitive detection of shrimp allergens in processed food

Food allergens that cause anaphylactic reactions have become an important health problem worldwide. Among them, shrimp is a popular seafood in many cuisines. The best way to avoid allergic reactions is to mitigate the intake of food allergens. In this study, a loop-mediated isothermal amplification (LAMP) assay was developed for the detection of shrimp DNA. Using LAMP primers, the identification of shrimp DNA by the LAMP assay was specific and rapid (within 30 min). It exhibited no cross-reaction with the DNA of other Crustacea, including crabs and lobster, and at least 0.01% shrimp DNA existed in the test sample. Additionally, the sensitivity of LAMP for detecting shrimp DNA was 100-fold greater than that of conventional PCR. LAMP for the detection of shrimp DNA was reproducible regardless of whether the genomic DNA was extracted from boiled, steamed or roasted shrimp samples. In summary, the LAMP assay established herein not only could be potentially used for diagnosing shrimp DNA but could also be applicable for identifying shrimp allergens in commercial food products in marketplaces.

Method for the Identification of Plant DNA in Food Using Alignment-Free Analysis of Sequencing Reads: A Case Study on Lupin

Fast and reliable analytical methods for the identification of plants from metagenomic samples play an important role in identifying the components of complex mixtures of processed biological materials, including food, herbal products, gut contents or environmental samples. Different PCR-based methods that are commonly used for plant identification from metagenomic samples are often inapplicable due to DNA degradation, a low level of successful amplification or a lack of detection power. We introduce a method that combines metagenomic sequencing and an alignment-free k-mer based approach for the identification of plant DNA in processed metagenomic samples. Our method identifies plant DNA directly from metagenomic sequencing reads and does not require mapping or assembly of the reads. We identified more than 31,000 Lupinus-specific 32-mers from assembled chloroplast genome sequences. We demonstrate that lupin DNA can be detected from controlled mixtures of sequences from target species (different Lupinus species) and closely related non-target species (Arachis hypogaea, Glycine max, Pisum sativum, Vicia faba, Phaseolus vulgaris, Lens culinaris, and Cicer arietinum). Moreover, these 32-mers are detectable in the following processed samples: lupin flour, conserved seeds and baked cookies containing different amounts of lupin flour. Under controlled conditions, lupin-specific components are detectable in baked cookies containing a minimum of 0.05% of lupin flour in wheat flour.

Food allergens: Classification, molecular properties, characterization, and detection in food sources

Food allergy is a large and growing public health problem in many areas of the world. The prevalence of food allergy has increased in the last decades in a very significant way in many world regions, particularly in developed countries. In that respect, the research field of food allergy has experienced an extensive growth and very relevant progress has been made in recent years regarding the characterization of food allergens, the study of their immunological properties, and their detection in food sources. Furthermore, food labeling policies have also been improved decidedly in recent years. For that immense progress made, it is about time to review the latest progress in the field of food allergy. In this review, we intend to carry out an extensive and profound overview regarding the latest scientific advances and knowledge in the field of food allergen detection, characterization, and in the study of the effects of food processing on the physico-chemical properties of food allergens. The advances in food labeling policies, and methodologies for the characterization of food allergens are also thoroughly reviewed in the present overview.

Use of IHF-QD Microscopic Analysis for the Detection of Food Allergenic Components: Peanuts and Wheat Protein

The aim of the study was to analytically evaluate quantum dots in immunohistofluorescence (IHF-QD) microscopic imaging as detectors of food allergens—peanut and wheat. The experiment was designed as two in silico experiments or simulations: (a) models of pastry samples were prepared with the addition of allergenic components (peanut and wheat protein components) and without the addition of allergenic components, and (b) positive and negative commercial samples underwent food allergen detection. The samples from both simulations were tested by the ELISA and IHF-QD microscopic methods. The primary antibodies (secondary antibodies to a rabbit Fc fragment with labeled CdSe/ZnS QD) were labelled at 525, 585, and 655 nm emissions. The use of quantum dots (QDs) has expanded to many science areas and they are also finding use in food allergen detection, as shown in the study. The study indicated that differences between the ELISA and IHF-QD microscopic methods were not observable among experimentally produced pastry samples with and without allergenic components, although differences were observed among commercial samples. The important value of the study is certainly the differences found in the application of different QD conjugates (525, 585, and 655). The highest contrast was found in the application of 585 QD conjugates that can serve for the possible quantification of present food allergens—peanuts and wheat. The study clearly emphasized that QD can be used for the qualitative detection of food allergens and can represent a reliable analytical method for food allergen detection in different food matrixes.

Nano-Biosensing Platforms for Detection of Cow's Milk Allergens: An Overview

Among prevalent food allergies, cow milk allergy (CMA) is most common and may persist throughout the life. The allergic individuals are exposed to a constant threat due to milk proteins' presence in uncounted food products like yogurt, cheese, and bakery items. The problem can be more severe due to cross-reactivity of the milk allergens in the food products due to homologous milk proteins of diverse species. This problem can be overcome by proper and reliable food labeling in order to ensure the life quality of allergic persons. Therefore, highly sensitive and accurate analytical techniques should be developed to detect the food allergens. Here, significant research advances in biosensors (specifically immunosensors and aptasensors) are reviewed for detection of the milk allergens. Different allergic proteins of cow milk are described here along with the analytical standard methods for their detection. Additionally, the commercial status of biosensors is also discussed in comparison to conventional techniques like enzyme-linked immunosorbent assay (ELISA). The development of novel biosensing mechanisms/kits for milk allergens detection is imperative from the perspective of enforcement of labeling regulations and directives keeping in view the sensitive individuals.

Detection and Quantification of Milk Ingredients as Hidden Allergens in Meat Products by a Novel Specific Real-Time PCR Method

Milk ingredients are often included in a wide range of meat products, such as cooked hams and sausages, to improve technological characteristics. However, milk proteins are also important food allergens. The aim of this study was the development of a highly sensitive and specific real-time PCR system targeting the 12S rRNA gene of Bos domesticus for the detection and quantification of milk as an allergenic ingredient in processed meat products. The method was able to achieve an absolute limit of detection (LOD) of 6 fg of milk DNA. Using a normalized approach (∆Ct method) for the detection of milk protein concentrate (MPC), it was possible to obtain sensitivities down to 0.01% (w/w) of MPC in model hams (raw and cooked) and autoclaved sausages, and 0.005% in raw sausage mixtures. The developed systems generally presented acceptable PCR performance parameters, being successfully validated with blind samples, applied to commercial samples, and further compared with an immunochemical assay. Trace amounts of milk material were quantified in two out of 13 samples, but the results mostly infer the excessive practice of the precautionary labeling.

Understanding how consumers with food allergies make decisions based on precautionary labelling

BACKGROUND

Understanding consumer perceptions is crucial if effective food safety policy and risk communication are to be developed and implemented. We sought to understand how those living with food allergy assess risk with precautionary allergen labelling (PAL) and their preference in how risks are communicated within a quantitative risk assessment (QRA) framework.

METHODS

The Integrated Approaches to Food Allergen and Allergy Risk Management (iFAAM) labelling online survey was developed for adults and parents of children with food allergy and distributed across Germany, Ireland, Netherlands, Spain and UK via patient support groups.

RESULTS

There were 1560 complete responses. 'This product is not suitable for' was selected as first choice for PAL by 46% overall and 'May contain' was selected as the first choice by 44%. Seventy-three percent reported that it would improve their trust in a product if a QRA process had been used to make a decision about whether to include 'may contain'. Overall, 66% reported that a 'statement + symbol' on the label indicating a QRA, would help them to understand the risk assessment process that had been used by the food manufacturer.

CONCLUSIONS

Consumers want to know what process has actually taken place for the placing of a PAL and/or risk assessment statement on a particular food product. Our findings provide a basis for the development of more informative communication around food allergen risk and safety and support evidence-based policy-making in the context of the legislative requirements of the European Union's Food Information for Consumers Regulation.

Reduced IgE/IgG binding capacities of bovine α-Lactalbumin by glycation after dynamic high-pressure microfluidization pretreatment evaluated by high resolution mass spectrometry

Dynamic high-pressure microfluidization (DHPM) pretreatment and glycation with lactose were employed to modify α-Lactalbumin (α-LA) with respect to the IgE/IgG binding capacities. No significant difference on incorporation ratio value of glycated α-LA was observed with and without DHPM pretreatment. However, IgE/IgG binding capacities of α-LA were decreased after glycation and DHPM pretreatment promoted the reduction. The lowest IgE/IgG binding capacities of glycated α-LA were obtained by DHPM pretreatment at 110 MPa. Native α-LA was mainly glycated at K62, K94, K98, whereas glycation sites and degree of substitution per peptide (DSP) were added after DHPM treatment. Therefore, the reduced IgE/IgG binding capacities of α-LA was attributed to the characteristics of glycated sites, including the amount, location, and DSP values. Interestingly, K98 played the most important role in decreasing IgE/IgG binding capacities of α-LA. The study revealed that glycation combined with DHPM was a promising way to decrease the allergenicity of proteins.

Feasibility of Utilizing Stable-Isotope Dimethyl Labeling in Liquid Chromatography⁻Tandem Mass Spectrometry-Based Determination for Food Allergens-Case of Kiwifruit

Stable-isotope dimethyl labeling is a highly reactive and cost-effective derivatization procedure that could be utilized in proteomics analysis. In this study, a liquid chromatography- tandem mass spectrometry in multiple reaction monitoring mode (LC-MS-MRM) platform for the quantification of kiwi allergens was first developed using this strategy. Three signature peptides for target allergens Act d 1, Act d 5, and Act d 11 were determined and were derivatized with normal and deuterated formaldehyde as external calibrants and internal standards, respectively. The results showed that sample preparation with the phenol method provided comprehensive protein populations. Recoveries at four different levels ranging from 72.5-109.3% were achieved for the H-labeled signature peptides of Act d 1 (SPA1-H) and Act d 5 (SPA5-H) with precision ranging from 1.86-9.92%. The limit of quantification (LOQ) was set at 8 pg mL^-1 for SPA1-H and at 8 ng mL^-1 for SPA5-H. The developed procedure was utilized to analyze seven kinds of hand-made kiwi foods containing 0.0175-0.0515 mg g^-1 of Act d 1 and 0.0252-0.0556 mg g^-1 of Act d 5. This study extended the applicability of stable-isotope dimethyl labeling to the economical and precise determination of food allergens and peptides.

Effects of thermal treatment on walnut detection and allergenicity

BACKGROUND

Peanuts and tree nut allergies pose an increasing food safety problem. The aim of our study was to test the accuracy of different commercial enzyme-linked immunosorbent assay (ELISA) kits in the detection of the presence of walnuts in untreated and heat exposed food samples. The effects of thermal treatment of samples were evaluated by exposing walnuts to different heat treatments. All samples were first analysed by two different commercial ELISA assays. Then, we performed a skin prick test (SPT) on nine patients with proven nut allergy using small walnut pieces from raw and treated samples.

RESULTS

The presence of nuts proteins in thermally processed foods was not accurately detected by ELISA kits. All patients had a positive SPT reaction with raw walnut, while thermal treatments affected walnut allergenicity. The ELISA test gives a negative result in the case of strong thermal treatment, but at the same time allergic subjects react positively to stimulation with the same sample.

CONCLUSION

This study suggests that commercial ELISA kits may not be able to accurately determine the amount of proteins present in thermally processed foods due to changes in the solubility and immunoreactivity of the target proteins. Finally, the clinical results highlight that thermal treatment might induce a reduction in walnut allergenicity. © 2018 Society of Chemical Industry.

A critical review of the specifications and performance of antibody and DNA-based methods for detection and quantification of allergens in foods

Despite the availability of a large number of antibody and DNA based methods for detection and quantification of allergens in food there remain significant difficulties in selecting the optimum technique to employ. Published methods from research groups mostly contain sufficient detail concerning target antigen, calibration procedures and method performance to allow replication by others. However, routine allergen testing by the food industry relies upon commercialised test kits and frequently the suppliers provide disappointingly little specification detail on the grounds that this is proprietary information. In this review we have made a critical assessment of the published literature describing the performance of both commercial and non-commercial test kits for food allergens over the period 2008-2018. Mass spectrometric methods, which have the potential to become reference methods for allergens, are not covered in this review. Available information on the specifications of commercial ELISA and LFD test kits are tabulated for milk, egg and peanut allergens, where possible linking to publications concerning collaborative studies and proficiency testing. For a number of commercial PCR test kits, specifications provided by manufacturers for detection of a small selection of allergen are tabulated. In conclusion we support the views of others of the critical need for allergen reference materials as the way forward to improve the comparability of different testing strategies in foods.

Duplex PCR-ELONA for the detection of pork adulteration in meat products

In this work, a duplex PCR-Enzyme Linked Oligonucleotide Assay (ELONA) is reported for the sensitive and reliable detection of pork adulteration in beef and chicken products, two of the most widely consumed meat types in the world. The strategy relies on the use of species-specific tailed primers for duplex amplification and simple dilution of the PCR reactions for direct colorimetric detection via hybridization, eliminating the need for any other post-amplification steps. A high sensitivity was achieved, with as low as 71-188 pg of genomic DNA able to be detected using mixtures of control DNA from each species. The strategy was validated using DNA add-mixtures as well as DNA extracted from raw meat mixtures and 0.5-1% w/w pork could be easily detected when mixed with beef or chicken. The proposed approach is simple, sensitive and cost-effective compared to equivalent commercial kits suitable for detecting adulterant pork levels in meat products.

A Comprehensive Review on Kiwifruit Allergy: Pathogenesis, Diagnosis, Management, and Potential Modification of Allergens Through Processing

Kiwifruit is rich in bioactive components including dietary fibers, carbohydrates, natural sugars, vitamins, minerals, omega-3 fatty acids, and antioxidants. These components are beneficial to boost the human immune system and prevent cancer and heart diseases. However, kiwifruit is emerging as one of the most common elicitors of food allergies worldwide. Kiwifruit allergy results from an abnormal immune response to kiwifruit proteins and occur after consuming this fruit. Symptoms range from the oral allergy syndrome (OAS) to the life-threatening anaphylaxis. Thirteen different allergens have been identified in green kiwifruit and, among these allergens, Act d 1, Act d 2, Act d 8, Act d 11, and Act d 12 are defined as the "major allergens." Act d 1 and Act d 2 are ripening-related allergens and are found in abundance in fully ripe kiwifruit. Structures of several kiwifruit allergens may be altered under high temperatures or strong acidic conditions. This review discusses the pathogenesis, clinical features, and diagnosis of kiwifruit allergy and evaluates food processing methods including thermal, ultrasound, and chemical processing which may be used to reduce the allergenicity of kiwifruit. Management and medical treatments for kiwifruit allergy are also summarized.

Noble Metal Nanoparticles Applications: Recent Trends in Food Control

Scientific research in the nanomaterials field is constantly evolving, making it possible to develop new materials and above all to find new applications. Therefore, nanoparticles (NPs) are suitable for different applications: nanomedicine, drug delivery, sensors, optoelectronics and food control. This review explores the recent trend in food control of using noble metallic nanoparticles as determination tools. Two major uses of NPs in food control have been found: the determination of contaminants and bioactive compounds. Applications were found for the determination of mycotoxins, pesticides, drug residues, allergens, probable carcinogenic compounds, bacteria, amino acids, gluten and antioxidants. The new developed methods are competitive for their use in food control, demonstrated by their validation and application to real samples.