Methods for allergen analysis in food: a review

Quantitative immunohistochemical method for detection of wheat protein in model sausage

Since gluten can induce coeliac symptoms in hypersensitive consumers with coeliac disease, it is necessary to label foodstuffs containing it. In order to label foodstuffs, it is essential to find reliable methods to accurately determine the amount of wheat protein in food. The objective of this study was to compare the quantitative detection of wheat protein in model sausages by ELISA and immunohistochemical methods. Immunohistochemistry was combined with stereology to achieve quantitative results. High correlation between addition of wheat protein and compared methods was confirmed. For ELISA method the determined values were r = 0.98, P < 0.01; for stereologythe determined values were r = 0.94, P < 0.01. Although ELISA is an accredited method, it was not reliable, unlike immunohistochemical methods (stereology SD = 3.1).

Multiplex detection of food allergens and gluten

To help safeguard the food supply and detect the presence of undeclared food allergens and gluten, most producers and regulatory agencies rely on commercial test kits. Most of these are ELISAs with a few being PCR-based. These methods are very sensitive and analyte specific, requiring different assays to detect each of the different food allergens. Mass spectrometry offers an alternative approach whereby multiple allergens may be detected simultaneously. However, mass spectrometry requires expensive equipment, highly trained analysts, and several years before a quantitative approach can be achieved. Using multianalyte profiling (xMAP®) technology, a commercial multiplex test kit based on the use of established antibodies was developed for the simultaneous detection of up to 14 different food allergens plus gluten. The assay simultaneously detects crustacean seafood, egg, gluten, milk, peanut, soy, and nine tree nuts (almond, Brazil nut, cashew, coconut, hazelnut, macadamia, pine nut, pistachio, and walnut). By simultaneously performing multiple tests (typically two) for each analyte, this magnetic bead-based assay offers built-in confirmatory analyses without the need for additional resources. Twenty-five of the assays were performed on buffer extracted samples, while five were conducted on samples extracted using reduced-denatured conditions. Thus, complete analysis for all 14 allergens and gluten requires only two wells of a 96-well microtiter plate. This makes it possible to include in a single analytical run up to 48 samples. All 30 bead sets in this multiplex assay detected 5 ng/mL of food allergen and gluten with responses greater than background. In addition, 26 of the bead sets displayed signal/noise ratios of five or greater. The bead-based design makes this 30-plex assay expandable to incorporate new antibodies and capture/detector methodologies by ascribing these new detectors to any of the unassigned bead sets that are commercially available.

Comparison of six commercial ELISA kits for their specificity and sensitivity in detecting different major peanut allergens

Six commercial peanut enzyme-linked immunosorbent assay kits were assessed for their ability to recover peanut from the standard reference material 2387 peanut butter and also for their specificity in detecting four major peanut allergens, Ara h 1, Ara h 2, Ara h 3, and Ara h 6. The percentage recovery of peanut from peanut butter differed across different kits as well as at different sample concentrations. The highest recovery was observed with the Romer and R-Biopharm kits, while four other kits were found to underestimate the protein content of the reference peanut butter samples. Five of the kits were most sensitive in detecting Ara h 3 followed by Ara h 1, while hardly recognizing Ara h 2 and Ara h 6. The other kit showed the highest sensitivity to Ara h 2 and Ara h 6, while Ara h 1 and Ara h 3 were poorly recognized. Although Ara h 2 and Ara h 6 are known to be heat stable and more potent allergens, antisera specific to any of these four peanut proteins/allergens may serve as good markers for the detection of peanut residues.

Quantification of bovine β-casein allergen in baked foodstuffs based on ultra-performance liquid chromatography with tandem mass spectrometry

The quantification of allergens in food including baked food matrices is of great interest. The aim of the present study was to describe a non-immunologic method to quantify bovine β-casein using ultra-performance liquid chromatography tandem triple quadrupole mass spectrometry (UPLC-TQ-MS/MS) in multiple reaction monitoring (MRM) mode. Eight of 10 theoretical peptides from β-casein after tryptic digestion were compared and MRM methods were developed to determine five signature peptides. The peptide VLPVPQK was selected as the signature peptide for bovine β-casein because of the high sensitivity. A stable isotope-labelled internal standard was designed to adjust the instability of sample pre-treatment and ionisation caused by matrix effect. Using the present suspension digestion method, the native and denatured β-casein could be digested to release the signature peptide at the maximum extent. The UPLC-TQ-MS/MS method developed based on a tryptic signature peptide led to a reliable determination of bovine β-casein allergen in baked food matrices at a low quantitation level down to 500 μg kg(-1) with a satisfactory accuracy (< 8.9%) and recovery (98.8% ± 2.6% to 106.7% ± 3.0%).

Quantitative detection of soybean in meat products by a TaqMan real-time PCR assay

In the present work, we propose a normalised real-time quantitative PCR assay to determine the addition of soybean to meat products. The method proved to be a powerful tool for the quantification of soybean protein (dry basis) in the range of 0.01% to 6%, being successfully in-house validated. Its application was effective in the analysis of several meat products, indicating 2% of non-compliance with the food allergen labelling legislation, and some inconsistencies when comparing the declared with estimated amounts of soybean. This work highlights the importance of efficient tools to assess labelling statements of meat products, avoiding fraudulent practices.

Detection of almond allergen coding sequences in processed foods by real time PCR

The aim of this work was to develop and analytically validate a quantitative RT-PCR method, using novel primer sets designed on Pru du 1, Pru du 3, Pru du 4, and Pru du 6 allergen-coding sequences, and contrast the sensitivity and specificity of these probes. The temperature and/or pressure processing influence on the ability to detect these almond allergen targets was also analyzed. All primers allowed a specific and accurate amplification of these sequences. The specificity was assessed by amplifying DNA from almond, different Prunus species and other common plant food ingredients. The detection limit was 1 ppm in unprocessed almond kernels. The method's robustness and sensitivity were confirmed using spiked samples. Thermal treatment under pressure (autoclave) reduced yield and amplificability of almond DNA; however, high-hydrostatic pressure treatments did not produced such effects. Compared with ELISA assay outcomes, this RT-PCR showed higher sensitivity to detect almond traces in commercial foodstuffs.

Mass Spectrometry-based Quantification of Proteins and Peptides in Food

The application of quantitative proteomics to food analysis is in its infancy. This is partly due to the diverse range of plant and animal species consumed as foods, many of which are not sequenced, making annotation of food proteomes difficult. In addition food processing procedures and interactions with other food components, such as lipids and starch, introduce a diverse range of chemical and conformational changes to proteins, many of which are poorly defined. Mass spectrometry-based molecular profiling has great potential as quality assurance tool for food authenticity and traceability, safety and quality. A driver for the application of quantitative protein mass spectrometry-based methods to food has been the need to develop confirmatory methods for allergen analysis in support of food allergen labelling regulations. In addition to providing rigorous quantitative methodology for complex biomacromolecules, protein mass spectrometry is also allowing us, for the first time, to discover how processing procedures modify the foods we eat at a molecular level. Such knowledge is essential if we are to understand how food processing can be used to optimise the beneficial health effects of foods.

Selection of recombinant antibodies by phage display technology and application for detection of allergenic Brazil nut (Bertholletia excelsa) in processed foods

Current immunological methods for detection of Brazil nut allergens in foods are based on polyclonal antibodies raised in animals. Phage display technology allows the procurement of high-affinity antibodies avoiding animal immunization steps and therefore attaining the principle of replacement supported by animal welfare guidelines. In this study, we screened Tomlinson I and J libraries for specific binders against Brazil nut by employing a Brazil nut protein extract and a purified Brazil nut 2S globulin, and we successfully isolated a phage single chain variable fragment (named BE95) that specifically recognizes Brazil nut proteins. The selected phage scFv was further used as affinity probe to develop an indirect phage-ELISA for detection of Brazil nut in experimental binary mixtures and in commercial food products, with a limit of detection of 5 mg g(-1). This study describes for the first time the isolation of recombinant antibody fragments specific for an allergenic tree nut protein from a naïve library and paves the way to develop new immunoassays for food analysis based on probes that can be produced in vitro when required and do not rely on animal immunization.

MS(E) based multiplex protein analysis quantified important allergenic proteins and detected relevant peptides carrying known epitopes in wheat grain extracts

The amount of clinically relevant, allergy-related proteins in wheat grain is still largely unknown. The application of proteomics may create a platform not only for identification and characterization, but also for quantitation of these proteins. The aim of this study was to evaluate the data-independent quantitative mass spectrometry (MS(E)) approach in combination with 76 wheat allergenic sequences downloaded from the AllergenOnline database ( www.allergenonline.org ) as a starting point. Alcohol soluble extracts of gliadin and glutenin proteins were analyzed. This approach has resulted in identification and quantification of 15 allergenic protein isoforms that belong to amylase/trypsin inhibitors, γ-gliadins, and high or low molecular weight glutenins. Additionally, several peptides carrying four previously discovered epitopes of γ-gliadin B precursor have been detected. These data were validated against the UniProt database, which contained 11764 Triticeae protein sequences. The identified allergens are discussed in relation to Baker's asthma, food allergy, wheat dependent exercise induced anaphylaxis, atopic dermatitis, and celiac disease (i.e., gluten-sensitive enteropathy). In summary, the results showed that the MS(E) approach is suitable for quantitative analysis and allergens profiling in wheat varieties and/or other food matrices.

Analysis to support allergen risk management: Which way to go?

Food allergy represents an important food safety issue because of the potential lethal effects; the only effective treatment is the complete removal of the allergen involved from the diet. However, due to the growing complexity of food formulations and food processing, foods may be unintentionally contaminated via allergen-containing ingredients or cross-contamination. This affects not only consumers' well-being but also food producers and competent authorities involved in inspecting and auditing food companies. To address these issues, the food industry and control agencies rely on available analytical methods to quantify the amount of a particular allergic commodity in a food and thus to decide upon its safety. However, no "gold standard methods" exist for the quantitative detection of food allergens. Nowadays mostly receptor-based methods and in particular commercial kits are used in routine analysis. However, upon evaluation of their performances, commercial assays proved often to be unreliable in processed foods, attributed to the chemical changes in proteins that affect the molecular recognition with the receptor used. Unfortunately, the analytical outcome of other methods, among which are chromatographic combined with mass spectrometric techniques as well as DNA-based methods, seem to be affected in a comparable way by food processing. Several strategies can be employed to improve the quantitative analysis of allergens in foods. Nevertheless, issues related to extractability and matrix effects remain a permanent challenge. In view of the presented results, it is clear that the food industry needs to continue to make extra efforts to provide accurate labeling and to reduce the contamination with allergens to an acceptable level through the use of allergen risk management on a company level, which needs to be supported inevitably by a tailor-validated extraction and detection method.

A personalized food allergen testing platform on a cellphone

We demonstrate a personalized food allergen testing platform, termed iTube, running on a cellphone that images and automatically analyses colorimetric assays performed in test tubes toward sensitive and specific detection of allergens in food samples. This cost-effective and compact iTube attachment, weighing approximately 40 grams, is mechanically installed on the existing camera unit of a cellphone, where the test and control tubes are inserted from the side and are vertically illuminated by two separate light-emitting-diodes. The illumination light is absorbed by the allergen assay, which is activated within the tubes, causing an intensity change in the acquired images by the cellphone camera. These transmission images of the sample and control tubes are digitally processed within 1 s using a smart application running on the same cellphone for detection and quantification of allergen contamination in food products. We evaluated the performance of this cellphone-based iTube platform using different types of commercially available cookies, where the existence of peanuts was accurately quantified after a sample preparation and incubation time of ~20 min per test. This automated and cost-effective personalized food allergen testing tool running on cellphones can also permit uploading of test results to secure servers to create personal and/or public spatio-temporal allergen maps, which can be useful for public health in various settings.

Detection of the soybean allergenic protein Gly m Bd 28K by an indirect enzyme-linked immunosorbent assay

The full-length cDNA sequence of Gly m Bd 28K was chemically synthesized and expressed in Escherichia coli (E. coli) BL21 (DE3) as an inclusion body under the induction of 0.2 mmol/L of isopropyl β-D-1-thiogalactopyranoside (IPTG). The purity of the recombinant protein was over 90% following Ni-nitrilotriacetic acid (Ni-NTA) affinity chromatography, and its molecular weight was 29.71 kDa. The polyclonal antibody (pAB) against Gly m Bd 28K was prepared and referred to as pAB-28K, and it exhibited high specificity for the protein in soybean meal. We established an indirect enzyme-linked immunosorbent assay (iELISA) using the pAB-28K and the recombinant Gly m Bd 28K protein to determine the Gly m Bd 28K content in soybean products. The R(2) value of the standard curve was 0.9910, the average relative standard deviation (RSD) was 16.93%, and the average recovery was 95.50%, which indicated that the iELISA was highly reproducible and accurate. Therefore, the pAB-28K and the iELISA provide valuable tools for the rapid and sensitive detection of Gly m Bd 28K in food and feed products from soybeans. This protocol meets the technical requirements for quality control and food safety as related to soybean.

Quantification of Gly m 4 protein, a major soybean allergen, by two-dimensional liquid chromatography with ultraviolet and mass spectrometry detection

Soybean (Glycine max) is considered a major allergenic food. Gly m 4 is one of several soybean allergens that has been identified to cause an allergic reaction, typically the symptoms are localized effects including the skin, gastrointestinal tract, or respiratory tract. Soybean allergens are considered a complete food allergen in that they are capable of inducing specific IgE as well as eliciting a range of severity from mild rashes up to anaphylaxis. In this study, we have isolated, purified, and characterized an endogenous Gly m 4 protein. The endogenous protein has 88.0% sequence homology with the theoretically predicted Gly m 4 sequence. Following detailed characterization, an assay was developed for quantification of endogenous Gly m 4 using two-dimensional liquid chromatography with ultraviolet and mass spectrometric detection (2DLC-UV/MS). A linear relationship (R(2) > 0.99) was observed over the concentration range of 12.5-531.7 μg/mL. Over the linear range, the assay recoveries (percent relative error, % RE) ranged from -1.5 to 10.8%. The assay precision (percent coefficient of variation, % CV) was measured at three different Gly m 4 levels on each of the 4 days and did not exceed 11.2%. The developed method was successfully applied to quantify Gly m 4 level in 10 commercial soybean lines. To the best of our knowledge, this represents the first quantitative assay for an intact endogenous Gly m 4 protein.

Electrochemical detection of peanut allergen Ara h 1 using a sensitive DNA biosensor based on stem-loop probe

A novel electrochemical DNA sensor was developed by using a stem-loop probe for peanut allergen Ara h 1 detection. The probe was modified with a thiol at its 5' end and a biotin at its 3' end. The biotin-tagged "molecular beacon"-like probe was attached to the surface of a gold electrode to form a stem-loop structure by self-assembly through facile gold-thiol affinity. 6-Mercaptohexanol (MCH) was used to cover the remnant bare region. The stem--loop probe was "closed" when the target was absent, and then the hybridization of the target induced the conformational change to "open", along with the biotin at its 3' end moved away from the electrode surface. The probe conformational change process was verified by circular dichroism (CD); meanwhile, electron-transfer efficiency changes between probe and electrode were proved by electrochemical impedance spectroscopy (EIS). The detection limit of this method was 0.35 fM with the linear response ranging from 10(-15) to 10(-10) M. Moreover, a complementary target could be discriminated from one-base mismatch and noncomplementarity. The proposed strategy has been successfully applied to detect Ara h 1 in the peanut DNA extracts of peanut milk beverage, and the concentration of it was 3.2 × 10(-13) mol/L.

Size-selective fractionation and visual mapping of allergen protein chemistry in Arachis hypogaea

Peanuts (Arachis hypogaea) in addition to milk, eggs, fish, crustaceans, wheat, tree nuts, and soybean are commonly referred to as the "big eight" foods that contribute to the majority of food allergies worldwide. Despite the severity of allergic reactions and growing prevalence in children and adults, there is no cure for peanut allergy, leaving avoidance as the primary mode of treatment. To improve analytical methods for peanut allergen detection, researchers must overcome obstacles involved in handling complex food matrices while attempting to decipher the chemistry that underlies allergen protein interactions. To address such challenges, we conducted a global proteome characterization of raw peanuts using a sophisticated GELFrEE-PAGE-LC-MS/MS platform consisting of gel-based protein fractionation followed by mass spectrometric identification. The in-solution mass-selective protein fractionation: (1) enhances the number of unique peptide identifications, (2) provides a visual map of protein isoforms, and (3) aids in the identification of disulfide-linked protein complexes. GELFrEE-PAGE-LC-MS/MS not only overcomes many of the challenges involved in the study of plant proteomics, but enriches the understanding of peanut protein chemistry, which is typically unattainable in a traditional bottom-up proteomic analysis. A global understanding of protein chemistry in Arachis hypogaea ultimately will aid the development of improved methods for allergen detection in food.

Expression of the soybean allergenic protein P34 in Escherichia coli and its indirect ELISA detection method

To detect the soybean allergen P34 (Gly m Bd 30K) from soybean products, the full-length cDNA sequence of P34 was synthesized and inserted into the prokaryotic expression vector pET-28a. The P34 protein was expressed in Escherichia coli BL21 (DE3) as an inclusion body under the induction of 0.8 mmol/L isopropyl β-D-1-thiogalactopyranoside. After purification with His-Bind affinity chromatography, the purity quotient of the recombinant protein was over 92 %, and its molecular weight (approximately 33 kDa) was very close to that of the native soybean P34. The polyclonal antibody (pAB) against P34 was prepared with the purified recombinant P34. The generated pAB, named as pAB-P34, exhibited high specificity to the P34 protein of the soybean meal. The indirect enzyme-linked immunosorbent assay (iELISA) based on pAB-P34 was established to determine the P34 content of soybean products. The CVs of the recovery tests of P34 were less than 7.77 %, which indicated that iELISA had high reproducibility and accuracy. Therefore, the recombinant P34 produced in the E. coli expression system, the prepared pAB-P34, and the developed iELISA could provide a valuable tool for sensitive detection of P34 in various soybean products and for future studies on allergies related to soybean P34.

Reducing the Allergenicity from Food by Microbial Fermentation

Food allergy has become a serious public health problem. Nowadays several treatments were employed for reducing the allergenicity from food. The paper mainly reviews the application of microbial fermentation in the reduction of the allergenicity from different foods.

Specific detection of potentially allergenic peach and apple in foods using polymerase chain reaction

Two PCR methods were developed for specific detection of the trnS-trnG intergenic spacer region of Prunus persica (peach) and the internal transcribed spacer region of Malus domestica (apple). The peach PCR amplified a target-size product from the DNA of 6 P. persica cultivars including 2 nectarine and 1 flat peach cultivar, but not from those of 36 nontarget species including 6 Prunus and 5 other Rosaceae species. The apple PCR amplified a target-size product from the DNA of 5 M. domestica cultivars, but not from those of 41 nontarget species including 7 Maloideae and 9 other Rosaceae species. Both methods detected the target DNA from strawberry jam and cookies spiked with peach and apple at a level equivalent to about 10 μg of total soluble proteins of peach or apple per gram of incurred food. The specificity and sensitivity were considered to be sufficient for the detection of trace amounts of peach or apple contamination in processed foods.

Simultaneous determination of two major snow crab aeroallergens in processing plants by use of isotopic dilution tandem mass spectrometry

Snow crab is a major fishery in the North Atlantic region. During crab processing the proteins are aerosolized and some are responsible for development of occupational asthma. Tropomyosin and arginine kinase have recently been reported as major snow crab allergens. A liquid chromatographic tandem mass spectrometric method has been developed for simultaneous analysis of these two proteins in air samples collected from processing plants. These proteins were initially isolated then characterized by use of mass spectrometry to determine their primary structure and signature peptides. The signature peptides were chemically synthesized in light and heavy forms and used as standards for developing the multiple-reaction monitoring transitions to monitor allergen levels. A validation study was performed; precision and accuracy were 1.8-8% and 91-104%, respectively. Replicate air samples were collected on air filters from two crab-processing plants in Newfoundland and Labrador (NL) and four located in Quebec. In NL, measured levels of both tropomyosin and arginine kinase were between 1 and 20 ng m(-3). In Quebec plants, however, levels were found to be much higher at 2-2400 ng m(-3). Significant differences were also observed among the plants and individual processing workstations. For the first time arginine kinase has been detected in its aerosolized form in processing plants. In general, levels of the allergens were highest in the butchering and cooking areas; plant design can, however, have a significant effect on levels of the allergens.

Current challenges in detecting food allergens by shotgun and targeted proteomic approaches: a case study on traces of peanut allergens in baked cookies

There is a need for selective and sensitive methods to detect the presence of food allergens at trace levels in highly processed food products. In this work, a combination of non-targeted and targeted proteomics approaches are used to illustrate the difficulties encountered in the detection of the major peanut allergens Ara h 1, Ara h 2 and Ara h 3 from a representative processed food matrix. Shotgun proteomics was employed for selection of the proteotypic peptides for targeted approaches via selective reaction monitoring. Peanut presence through detection of the proteotypic Ara h 3/4 peptides AHVQVVDSNGNR (m/z 432.5, 3+) and SPDIYNPQAGSLK (m/z 695.4, 2+) was confirmed and the developed method was able to detect peanut presence at trace levels (≥10 μg peanut g(-1) matrix) in baked cookies.

Quantification of cow's milk percentage in dairy products - a myth?

The substitution of ewe's and goat's milk for cheaper cow's milk is still a fraudulent practice in the dairy industry. Moreover, soy-based products (e.g., soy milk, yoghurt) have to be checked for cow's milk as they are an alternative for people suffering from an allergy against bovine milk proteins. This work reports the evaluation of different protein-based electrophoretic methods and DNA-based techniques for the qualitative detection as well as the quantitative determination of cow's milk percentage in dairy and soy milk products. Isoelectric focusing (IEF) of γ-caseins using an optimized pH gradient was appropriate not only for the detection of cow's milk, but also for an estimation of cow's milk percentage in mixed-milk cheese varieties. Urea-polyacrylamide gel electrophoresis (PAGE) proved the method of choice to detect cow's milk in soy milk products, whereas IEF and SDS-PAGE of proteins were not applicable due to false-positive results. Polymerase chain reaction (PCR) analysis was used to confirm the results of protein-based electrophoretic methods. Problems inherent in quantitative analysis of cow's milk percentage using protein-based techniques and even more using DNA-based methods were emphasized. Applicability of quantitative real-time PCR for the determination of cow's milk percentage in mixed-milk cheese was shown to be hampered by several factors (e.g., somatic cell count of milk; technological parameters influencing the final DNA concentration in ripened commercial cheese samples). The implementation of certified reference standards (of major relevant cheese groups) containing 50% cow's milk was urgently recommended to enable at least a yes/no decision in commercial mixed-milk cheese samples.

Almond allergens: molecular characterization, detection, and clinical relevance

Almond ( Prunus dulcis ) has been widely used in all sorts of food products (bakery, pastry, snacks), mostly due to its pleasant flavor and health benefits. However, it is also classified as a potential allergenic seed known to be responsible for triggering several mild to life-threatening immune reactions in sensitized and allergic individuals. Presently, eight groups of allergenic proteins have been identified and characterized in almond, namely, PR-10 (Pru du 1), TLP (Pru du 2), prolamins (Pru du 2S albumin, Pru du 3), profilins (Pru du 4), 60sRP (Pru du 5), and cupin (Pru du 6, Pru du γ-conglutin), although only a few of them have been tested for reactivity with almond-allergic sera. To protect sensitized individuals, labeling regulations have been implemented for foods containing potential allergenic ingredients, impelling the development of adequate analytical methods. This work aims to present an updated and critical overview of the molecular characterization and clinical relevance of almond allergens, as well as review the main methodologies used to detect and quantitate food allergens with special emphasis on almond.

MALDI based identification of soybean protein markers--possible analytical targets for allergen detection in processed foods

Soybean (Glycine max) is extensively used all over the world due to its nutritional qualities. However, soybean is included in the "big eight" list of food allergens. According to the EU directive 2007/68/EC, food products containing soybeans have to be labeled in order to protect the allergic consumers. Nevertheless, soybeans can still inadvertently be present in food products. The development of analytical methods for the detection of traces of allergens is important for the protection of allergic consumers. Mass spectrometry of marker proteolytical fragments of protein allergens is growingly recognized as a detection method in food control. However, quantification of soybean at the peptide level is hindered due to limited information regarding specific stable markers derived after proteolytic digestion. The aim of this study was to use MALDI-TOF/MS and MS/MS as a fast screening tool for the identification of stable soybean derived tryptic markers which were still identifiable even if the proteins were subjected to various changes at the molecular level through a number of reactions typically occurring during food processing (denaturation, the Maillard reaction and oxidation). The peptides (401)Val-Arg(410) from the G1 glycinin (Gly m 6) and the (518)Gln-Arg(528) from the α' chain of the β-conglycinin (Gly m 5) proved to be the most stable. These peptides hold potential to be used as targets for the development of new analytical methods for the detection of soybean protein traces in processed foods.

Analysis of olive allergens

Olive pollen is one of the most important causes of seasonal respiratory allergy in Mediterranean countries, where this tree is intensely cultivated. Besides this, some cases of contact dermatitis and food allergy to the olive fruit and olive oil have been also described. Several scientific studies dealing with olive allergens has been reported, being the information available about them constantly increasing. Up to date, twelve allergens have been identified in olive pollen while just one allergen has been identified in olive fruit. This review article describes considerations about allergen extraction and production, also describing the different methodologies employed in the physicochemical and immunological characterization of olive allergens. Finally, a revision of the most relevant studies in the analysis of both olive pollen and olive fruit allergens is carried out.