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

Quantitation of milk proteins in thermally treated milk samples and commercial food products by ELISA test kits

This study evaluated four ELISA kits for quantitation of milk proteins in thermally treated milk samples and food products. How reference materials may be used for comparison of kit performance was examined. Protein contents determined by Veratox Total Milk generally reflected those determined by the 660 nm total protein assay. BioKits BLG Kit was less affected by thermal treatment but resulted in overestimation of protein contents in samples that were boiled, autoclaved or dry-heated at ≤149 °C, while ELISA Systems Casein (ES Casein) and Beta-Lactoglobulin (ES BLG) assays underestimated protein levels in these samples. The four kits gave similar results for ice cream. Veratox registered higher concentrations in all products tested but its sensitivity was greatly lowered in retorted products. ES Casein underperformed Veratox for baked and retorted products. BioKits BLG maintained a better sensitivity towards fried, baked and retorted products while ES BLG exhibited reduced sensitivity for these products.

Validation Procedures for Quantification of Food Allergens by Enzyme-Linked Immunosorbent Assay (ELISA)

Enzyme-linked immunosorbent assay (ELISA) is a widely used analytical technique for food allergen detection and quantification. Validating ELISA protocols is important for both assay developers and end users as it ensures method reliability. This chapter describes the protocols for validating the sensitivity, specificity, precision, accuracy, robustness, and ruggedness of an ELISA. Example procedures are also provided for sample preparation, allergen extraction, and ELISA operation.

Versatile Application of Nanobodies for Food Allergen Detection and Allergy Immunotherapy

The unique characteristics of camelid heavy-chain only antibody (HCAb) derived nanobodies (Nbs) have facilitated their employment as tools for research and application in extensive fields including food safety inspection, diagnosis and therapy of diseases, etc., to develop immune detecting techniques or alternative candidates of conventional antibodies as diagnostic and therapeutic reagents. The wide application in the fields of food allergen inspection and immunotherapy has not been addressed as not much results published in the literature. The robust properties and straightforward selecting strategy of Nbs impel the advantageous employment compared with monoclonal antibodies (mAbs) to establish immunoassay and serve as blocking antibodies to compete immunoglobulin E (IgE) binding epitopes on food allergens. More and more efforts have been invested to develop specific Nbs against food allergen proteins, such as macadamia allergen of Mac i 1, peanut allergen of Ara h 3, and lupine allergen of Lup an 1, which demonstrated the potential of Nbs for research and application in food allergen surveillance. Meanwhile, the paratopes of Nbs preferably targeting the unique epitopes of food allergens can provide more possibilities to serve as blocking antibodies to shield IgE binding epitopes for food allergy immunotherapy. Regardless, the research and application of Nbs in the field of food allergen and allergic reactions are expected to attract dramatic focus and produce promising research outputs.

Development of sandwich ELISA and lateral flow immunoassay to detect almond in processed food

Almond (Prunus dulcis) represents a potential allergenic hazard that should be included in Allergen Control Plans. In this study, sandwich ELISA and lateral flow immunoassay (LFIA), using amandin (Pru du 6) as the target protein, were developed to detect almond in processed food and validated according to international guides. ELISA could detect 2 ng/mL and LFIA 30 ng/mL of pure amandin. No cross-reactivity was found on a panel of 50 food commodities with the exception of Pecan nut, Brazil nut and chestnut for which the cross-reactivity was lower than 0.02%. Furthermore, ELISA and LFIA were able to detect 0.12 and 0.70 ppm of almond protein in foods spiked with almond extract whereas 0.20 and 2.0 ppm could be detected in baked cookies incurred with almond, respectively. Both techniques could be applied for food manufacturers and control agencies for monitoring the presence of almond traces in food and working surfaces.

The “Healthy Meals” web app for the assessment of nutritional content and food allergens in restaurant meals: Development, evaluation and validation

Objective

The development and the evaluation of the Healthy Meals web app designed for professionals from different disciplines related to food, aimed to assess the nutritional and food allergen content of restaurant meals, was described.

Methods

App evaluation concerned: (1) usability, scored on a 7-point scale by 6 restaurateurs and 10 nutritionists through the Computer System Usability Questionnaire; (2) quality, scored on a 5-point scale by 10 nutritionists through the Mobile App Rating Scale; (3) validation, by two nutritionists through differences in entered nutrient contents. Ratings reliability was assessed by the interclass correlation coefficient.

Results

Users agreed with the web app usability (mean 5.6/7 points, SD 0.9), with moderate reliability among ratings (interclass correlation coefficient = 0.57; 95% CI, 0.18 to 0.82). The web app showed good objective quality (mean 4.0/5 points, SD 0.4), with excellent reliability among nutritionists (interclass correlation coefficient = 0.91; 95% CI, 0.85 to 0.96). For web app validation, no significant differences were observed between the two nutritionists’ data, with excellent reliability (interclass correlation coefficient = 0.98; 95% CI, 0.97 to 0.99). App data entry was identified as a point to improve.

Conclusions

The Healthy Meals web app designed for professionals related to food, such as restaurateurs, demonstrated to be usable, of good quality and valid for dishes nutritional assessment and food allergen identification. Points to improve were identified, while app effectiveness should be tested in trials.

Improved Sensitivity of Allergen Detection by Immunoaffinity LC-MS/MS Using Ovalbumin as a Case Study

Food allergies are caused by severe hypersensitivity to specific food allergens such as the egg protein ovalbumin. It is therefore important to test food products for the presence of allergens to protect allergic people from accidental ingestion. For egg detection, ELISA is the only reasonable commercially available test format, although the recognition of target allergens can be affected by food processing, which may lead to false negative results. Current mass spectrometry-based detection methods may overcome this issue, but these approaches are often less sensitive. Here we combined the advantages of antibody-based and MS-based methods by developing an immunoaffinity LC-MS/MS technique to detect the common egg allergen Gal d 2. We investigated the principal functionality of this method with incurred cookie material containing whole egg powder. We found that the new method matched easily the sensitivity of egg specific ELISA tests. Further western blot experiments indicated that this strategy may be unaffected by food processing, providing an important alternative strategy for the detection and quantification of allergens in food.

Visual detection of tropomyosin, a major shrimp allergenic protein using gold nanoparticles (AuNPs)-assisted colorimetric aptasensor

A gold nanoparticle-based label-free colorimetric assay was developed to detect the shrimp allergenic protein tropomyosin (TM), an important biomarker responsible for severe clinical reactivity to shellfish. In a gold nanoparticles (AuNPs)-tropomyosin-binding aptamer (TMBA) complex, the aptamer adsorbs onto the surface of AuNPs and dissociates in the presence of TM. In addition, AuNPs tend to aggregate in the presence of ionic salt, revealing a color change (i.e., wine-red to purple/blue) with a shift in the maximum absorption peak from 520 nm. In the presence of specific binding TM, the aptamer folds into a tertiary structure where it more efficiently stabilizes AuNPs toward the salt-induced aggregation with a hypsochromic shift in the absorption spectra compared to the stabilized AuNPs by aptamer alone. Based on the aggregation and sensitive spectral transformation principle, the AuNPs-based colorimetric aptasensor was successfully applied to detect TM with a range of 10-200 nmol/L and a low detection limit of 40 nmol/L in water samples. The reliability, selectivity, and sensitivity of the aptasensor was then tested with food samples spiked with TM. The observed detection limit was as low as 70 nmol/L in shrimp, 90 nmol/L in tofu, and 80 nmol/L in eggs, respectively. We anticipate the proposed AuNPs-based colorimetric aptasensor assay possesses a high potential for the easy and efficient visual colorimetric detection of TM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-020-00085-5.

Multi-target detection of egg-white and pig gelatin fining agents in Nebbiolo-based aged red wine by means of nanoHPLC-HRMS

The presence of residues from fining agents in wines may represent a risk for allergic consumers and a source of discomfort for others, such as vegans. Even though ELISA is the official detection method for such residues, this technique may be hindered by cross-reactivity issues, or by matrix-molecule interference due to a high polyphenol content, especially in red wines. An HRMS-based method has been developed to detect pig gelatin and egg white in experimental five-year aged Nebbiolo-based red wine. Biomarker peptides were selected, after tryptic digestion, and quantified by multitarget nanoHPLC-HRMS analysis. The method resulted in an LLOQs of 5 µg/mL in the experimental wine, and between 1 and 2 µg/mL in the buffer. This method allowed both gelatin and egg white proteins to be detected and quantified in aged red wine, while whereas the commercial ELISA kit was instead unable to detect egg white in the same samples.

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.

Influence of different extraction conditions on the detection of glycinin and β-conglycinin in model processed foods by ELISA

The presence of undeclared soy proteins in food can cause severe reactions in soy allergic individuals. The extraction of target proteins from processed foods is a crucial step in allergen detection by immunoassays, as only successfully extracted target proteins can be detected by the specific antibodies. The effectiveness was studied of different conditions (type of buffer, temperature and time of incubation) on the extraction of total protein, and concentration of glycinin and β-conglycinin from different food matrices. The yields were determined using a soy protein isolate and three processed foods (sausage, bread and pâté) incurred with soy proteins. The yields were affected by the processing of analysed products and the composition and pH of the extraction buffers. Neutral and alkaline buffers (pH from 7.4 to 10.6) exhibited good protein extraction capacity and detectability of the specific target proteins. Denaturing additives and highly alkaline buffer (pH 12) extracted more crude protein but they were incompatible with the ELISA assay. Overall, the best results were obtained using phosphate (pH 7.4) and Tris/HCl (pH 8.5) buffers in the presence of 0.5 M NaCl. Crude protein yield of food extracts did not correlate with that of glycinin and β-conglycinin, whereas a good relationship was found between the yields of the two proteins.

Folding-Based Electrochemical Aptasensor for the Determination of β-Lactoglobulin on Poly-L-Lysine Modified Graphite Electrodes

Nowadays, food allergy is a very important health issue, causing adverse reactions of the immune system when exposed to different allergens present in food. Because of this, the development of point-of-use devices using miniaturized, user-friendly, and low-cost instrumentation has become of outstanding importance. According to this, electrochemical aptasensors have been demonstrated as useful tools to quantify a broad variety of targets. In this work, we develop a simple methodology for the determination of β-lactoglobulin (β-LG) in food samples using a folding-based electrochemical aptasensor built on poly-L-lysine modified graphite screen-printed electrodes (GSPEs) and an anti-β-lactoglobulin aptamer tagged with methylene blue (MB). This aptamer changes its conformation when the sample contains β-LG, and due to this, the spacing between MB and the electrode surface (and therefore the electron transfer efficiency) also changes. The response of this biosensor was linear for concentrations of β-LG within the range 0.1-10 ng·mL-1, with a limit of detection of 0.09 ng·mL-1. The biosensor was satisfactorily employed for the determination of spiked β-LG in real food samples.

Simplified Tracking of a Soy Allergen in Processed Food Using a Monoclonal Antibody-Based Sandwich ELISA Targeting the Soybean 2S Albumin Gly m 8

Soybean allergens in food samples are currently detected in most cases using enzyme-linked immunosorbent assays (ELISAs) based on antibodies raised against bulk soybean proteins or specifically targeting soybean trypsin inhibitor, conglycinin, or glycinin. The various commercial ELISAs lack standardized reference material, and the results are often inaccurate because the antibodies cross-react with proteins from other legumes. Furthermore, the isolation of allergenic proteins involves laborious denaturing extraction conditions. To tackle these challenges, we have developed a novel sandwich ELISA based on monoclonal antibodies raised against the soybean 2S albumin Gly m 8 and a recombinant Gly m 8 reference protein with native-analogous characteristics. The antibodies do not cross-react with other legume proteins, and the extraordinary stability and solubility of Gly m 8 allows it to be extracted even from complex matrices after processing. The Gly m 8 ELISA therefore achieves greater specificity and reproducibility than current ELISA tests.

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.

The role of incurred materials in method development and validation to account for food processing effects in food allergen analysis

The issue of undeclared allergens represents a matter of great concern, being the subject of many alert notifications by the Rapid Alert System for Food and Feed portal of the European Commission, often leading to food recalls. The availability of reliable analytical approaches able to detect and quantify hidden allergens in processed foods is increasingly requested by the food industry, food safety authorities and regulatory bodies to protect sensitive consumers' health. The present review discusses the fundamental role of incurred materials for method development and analytical performance assessment in a metrology perspective on testing for undeclared allergens in processed foodstuffs. Due to the nature of the analytes and their susceptibility to various processing effects, reliability and comparability of results have posed a great challenge. In this context, the use of incurred samples as reference materials permits simulation of the effects of food processing on target analyte structure affecting analyte extractability and detectability. Graphical abstract ᅟ.

Highly Sensitive Detection of Bovine β-Lactoglobulin with Wide Linear Dynamic Range Based on Platinum Nanoparticles Probe

Cow's milk allergy is one of the most frequent and severe IgE-induced food allergies for children, demanding sensitive analytical methods, and β-lactoglobulin (BLG) can be as an important biomarker for detection of milk protein. In this study, a highly sensitive sandwich enzyme-linked immunosorbent assay (sELISA) based on a specific polyclonal antibody against human IgE linear epitopes of BLG and an anti-BLG polyclonal antibody-platinum nanoparticles probe was described for detection of BLG. This sELISA exhibited an ultrawide linear range of 0.49-1.6 × 10⁴ ng/mL, covering more than four orders of magnitude. The limit of detection was 0.12 ng/mL, which was 16-fold lower than that using traditional sELISA with the same antibodies. Furthermore, the proposed approach showed high recoveries (93.53%-111.95%) and low coefficient of variation (1.49%-12.50%) after analysis of samples fortified with BLG. The presence of allergenic BLG residues also could be detected in partially hydrolyzed infant formulas. These results, in comparison with conventional and commercial BLG detection sELISAs, highlight that this proposed sELISA could be a reliable and user-friendly tool to monitor trace amounts of BLG and its potentially allergenic residues in foods.

Recent progress on cell-based biosensors for analysis of food safety and quality control

Food quality and safety has become a subject of major concern for authorities and professionals in the food supply chain. Rapid methods, particularly biosensors, have exceptional specificity and sensitivity, rapid response times, low cost, relatively compact size, and are user friendly to operate. Cell-based biosensors are portable, and provide the biological activity of the analyte suitable for an initial screening of food. In this overview, the utilization of cell-based biosensors for food safety and quality analyses, such as detecting toxins, foodborne pathogens, allergens, and evaluating toxicity and function are summarized. Our results will promote the future development of cell-based biosensors in the food field.

The sensory quality of allergen-controlled, fat-reduced, salt-reduced pork-ostrich sausages during storage

BACKGROUND

New meat products tailored to consumer health should be characterised by reduced sodium, fat and cholesterol contents and other health-promoting benefits. However, the food sector's greatest challenge is allergen-free production. Consumers are not willing to compromise the sensory quality of meat products for health. The aim of the present study was to analyse the influence of the storage time on the physical properties and consumer acceptance of allergen-controlled, fat-reduced, salt-reduced pork-ostrich sausages. The study focused on pork-ostrich sausages produced in accordance with a new patented technology, which focused on eliminating cross-contamination on-line in the plant, eliminating cross-contamination after preparation, and eliminating spices with high allergy potential. The production was focused on reducing fat (by approximately 50%) and salt (by approximately 30%) levels.

RESULTS

No changes in the texture parameters of the sausage were observed during storage time; however, some changes in colour were observed. There were no significant differences in sensory consumer acceptability of pork-ostrich sausage after 14 days of storage; thus, it may be stated that the instrumentally assessed differences in colour did not influence consumer acceptance.

CONCLUSION

The applied fat and NaCl reduction in the pork-ostrich sausages contributed to high consumer ratings and was not correlated with saltiness acceptability. © 2017 Society of Chemical Industry.

Construction of a lateral flow strip for detection of soymilk in milk

A lateral flow based detection method for ascertaining the presence of soymilk in whole bovine milk has been described. The method uses commercially available rabbit anti-soy protein antibodies conjugated to gold nanoparticles (AuNPs) wherein soymilk protein in adulterated milk and soymilk protein at test line competes for limited antibodies. At control line, anti-rabbit immunoglobulin was immobilized for ensuring flow properties of antibody-conjugated AuNPs. Absence or diminished intensity of band at test line indicates presence of soymilk in milk. The soymilk detection limit was 1.75% (v/v) in whole bovine milk and results are available in 5 min. Constructed lateral flow device can be used for on-spot examination of soymilk in milk.

Molecular allergy diagnostic tests: development and relevance in clinical practice

Molecular allergy is based on identification, characterization and subsequent use of single allergens, being components of complex allergen sources like pollen, mites, furred animals, foods or insect venoms. Only few protein families contain relevant allergens of similar sequence and structure, carrying common IgE epitopes as the basis of cross reactivity. Used as purified or recombinant (glyco)proteins single allergens can potentially improve in-vitro diagnostics, particularly allergen-specific IgE assays through a) increased sensitivity, b) use of risk and marker allergens, c) component-resolved diagnostics (CRD). CRD can differentiate primary, species-specific from secondary, cross-reactive sensitizations to single allergens. Allergen components facilitate an increased analytical sensitivity, particularly if they are underrepresented or missing in conventional allergen extracts. They are mainly used in single assays (singleplex) for the detection of IgE, but also in a microarray format (multiplex) with 112 components from 50 allergen sources with slightly decreased analytical sensitivity. Concepts of molecular allergy can only be separately defined and utilized for each allergen source (pollen, mites, foods or insect venoms). As soon as essential singe allergens are available, their specific role in diagnostics should be defined. This requires well characterized patient cohorts from various countries, since exposure, allergic immune response and clinical relevance can vary substantially between individual subjects and geographical regions. The patient's clinical information is essential for proper interpretation of molecular allergology results. The history and/or challenge test results will finally provide evidence, in how far a sensitization to single allergens might be clinically relevant or not.

Detection and Antigenic Profiling of Undeclared Peanut in Imported Garlic Using an xMAP Multiplex Immunoassay for Food Allergens

A shipment of imported garlic powder was suspected of containing peanut. Samples (subs) collected from the shipment displayed considerable variability in peanut antigenicity when analyzed by enzyme-linked immunosorbent assay (ELISA). This raised questions regarding whether peanut was actually present, the amount present, and the basis for the variability in antigenic content. Analyses that used an xMAP multiplex assay for the detection of peanut and additional food allergens generated responses that were characteristic of peanut. Specifically, the relative intensities of two different peanut-specific antibodies coupled to beads (peanut-37 and -38) and the antigen profiles were identical to garlic controls spiked with peanut. In addition, the xMAP data did not indicate the presence of other allergens. Quantitative analyses indicated an approximately fivefold variation in peanut concentration among different subs. In contrast, within a sub, the apparent peanut concentration appeared constant. Particle size analyses of the garlic powder subs indicated a single distribution profile, with a peak at 380 μm. ELISA analysis of sieve-fractionated garlic powder from one of the subs indicated that slightly less than half of the detectable peanut was smaller than 212 μm, with the remainder almost evenly split between 212 and 300 μm and >300 μm. Modeling to predict possible oral exposure levels of peanut other than those directly measured requires additional research on the physicochemical properties of peanut and garlic, along with information on the production of the garlic powder.

Hazard analysis approaches for certain small retail establishments in view of the application of their food safety management systems

Under current European hygiene legislation, food businesses are obliged to develop and implement food safety management systems (FSMS) including prerequisite programme (PRP) activities and hazard analysis and critical control point principles. This requirement is especially challenging for small food retail establishments, where a lack of expertise and other resources may limit the development and implementation of effective FSMS. In this opinion, a simplified approach to food safety management is developed and presented based on a fundamental understanding of processing stages (flow diagram) and the activities contributing to increased occurrence of the hazards (biological, chemical (including allergens) or physical) that may occur. The need to understand and apply hazard or risk ranking within the hazard analysis is removed and control is achieved using PRP activities as recently described in the European Commission Notice 2016/C278, but with the addition of a PRP activity covering ‘product information and customer awareness’. Where required, critical limits, monitoring and record keeping are also included. Examples of the simplified approach are presented for five types of retail establishments: butcher, grocery, bakery, fish and ice cream shop.

Use of Foodomics for Control of Food Processing and Assessing of Food Safety

Food chain, food safety, and food-processing sectors face new challenges due to globalization of food chain and changes in the modern consumer preferences. In addition, gradually increasing microbial resistance, changes in climate, and human errors in food handling remain a pending barrier for the efficient global food safety management. Consequently, a need for development, validation, and implementation of rapid, sensitive, and accurate methods for assessment of food safety often termed as foodomics methods is required. Even though, the growing role of these high-throughput foodomic methods based on genomic, transcriptomic, proteomic, and metabolomic techniques has yet to be completely acknowledged by the regulatory agencies and bodies. The sensitivity and accuracy of these methods are superior to previously used standard analytical procedures and new methods are suitable to address a number of novel requirements posed by the food production sector and global food market.

Aptamer Lateral Flow Assays for Ultrasensitive Detection of β-Conglutin Combining Recombinase Polymerase Amplification and Tailed Primers

In this work, different methodologies were evaluated in search of robust, simple, rapid, ultrasensitive, and user-friendly lateral flow aptamer assays. In one approach, we developed a competitive based lateral flow aptamer assay, in which β-conglutin immobilized on the test line of a nitrocellulose membrane and β-conglutin in the test sample compete for binding to AuNP labeled aptamer. The control line exploits an immobilized DNA probe complementary to the labeled aptamer, forcing displacement of the aptamer from the β-conglutin-aptamer complex. In a second approach, the competition for aptamer binding takes place off-strip, and following competition, aptamer bound to the immobilized β-conglutin is eluted and used as a template for isothermal recombinase polymerase amplification, exploiting tailed primers, resulting in an amplicon of a duplex flanked by single stranded DNA tails. The amplicon is rapidly and quantitatively detected using a nucleic acid lateral flow with an immobilized capture probe and a gold nanoparticle labeled reporter probe. The competitive lateral flow is completed in just 5 min, achieving a detection limit of 55 pM (1.1 fmol), and the combined competitive-amplification lateral flow requires just 30 min, with a detection limit of 9 fM (0.17 amol).

Food Allergy

Food allergy is receiving increased attention in recent years. Because there is currently no known cure for food allergy, avoiding the offending food is the best defense for sensitive individuals. Type I food allergy is mediated by food proteins, and thus, theoretically, any food protein is a potential allergen. Variability of an individual's immune system further complicates attempts to understand allergen-antibody interaction. In this article, we briefly review food allergy occurrence, prevalence, mechanisms, and detection. Efforts aimed at reducing/eliminating allergens through food processing are discussed. Future research needs are addressed.

Bioanalytical methods for food allergy diagnosis, allergen detection and new allergen discovery

For effective monitoring and prevention of the food allergy, one of the emerging health problems nowadays, existing diagnostic procedures and allergen detection techniques are constantly improved. Meanwhile, new methods are also developed, and more and more putative allergens are discovered. This review describes traditional methods and summarizes recent advances in the fast evolving field of the in vitro food allergy diagnosis, allergen detection in food products and discovery of the new allergenic molecules. A special attention is paid to the new diagnostic methods under laboratory development like various immuno- and aptamer-based assays, including immunoaffinity capillary electrophoresis. The latter technique shows the importance of MS application not only for the allergen detection but also for the allergy diagnosis.

Validation of a mass spectrometry-based method for milk traces detection in baked food

A simple validated LC-MS/MS-based method was set up to detect milk contamination in bakery products, taking the effects of food processing into account for the evaluation of allergen recovery and quantification. Incurred cookies were prepared at eight levels of milk contamination and were cooked to expose all milk components, including allergenic proteins, to food processing conditions. Remarkable results were obtained in term of sufficiently low LOD and LOQ (1.3 and 4 mg/kg cookies, respectively). Precision was calculated as intra-day repeatability (RSD in the 5-20% range) and inter-day repeatability (4 days; RSD never exceeded 12%). The extraction recovery values ranged from 20% to 26%. Method applicability was evaluated by analysing commercial cookies labelled either as "milk-free" or "may contain milk". Although the ELISA methodology is considered the gold standard for detecting allergens in foods, this robust LC-MS/MS approach should be a useful confirmatory method for assessing and certifying "milk-free" food products.

Rapid and sensitive detection of the food allergen glycinin in powdered milk using a lateral flow colloidal gold immunoassay strip test

A rapid immunochromatographic lateral flow test strip in a sandwich format was developed with the colloidal gold-labeled mouse antiglycinin monoclonal antibody (mAb) and rabbit antiglycinin polyclonal antibody (pAb) to specifically identify glycinin, a soybean allergen. The test strip is composed of a sample pad, a conjugate reagent pad, an absorbent pad, and a test membrane containing a control line and a test line. This test strip has high sensitivity, and results can be obtained within 10 min without sophisticated procedures. The limit of detection (LOD) of the test strip was calculated to be 0.69 mg/kg using an optical density scanner that measures relative optical density. The assay showed high specificity for glycinin, with no cross-reactions with other soybean proteins or other food allergens. The recoveries of the lateral flow test strip in detecting glycinin in powdered milk samples ranged between 80.5 and 89.9% with relative standard deviations of less than 5.29% (intra-assay) and 6.72% (interassay). Therefore, the test strip is useful as a quantitative, semiquantitative, or qualitative detection method for glycinin in powdered milk. In addition, the test strip can be used to detect glycinin in other processed foods and may be a valuable tool in identifying effective approaches for reducing the impact of glycinin.

Evaluation of the efficiency of enological procedures on lysozyme depletion in wine by an indirect ELISA method

Potential residues of the potent allergen lysozyme used as a microbial stabilizing agent in wine production might pose a serious health thread to susceptible individuals. Therefore, EU legislation requires the labeling of the allergenic agent, if it is present in the final product. To allow for product testing, an indirect ELISA method to be specifically used in wine analysis was developed and validated. Furthermore, trial wines treated with defined amounts of lysozyme were subjected to an array of different filtration and other enological processing regimes in order to evaluate their potential to deplete the allergen content of the wines. By these means, processing methods ought to be identified that can be integrated in a good manufacturing practice guideline to enable wine producers to utilize lysozyme in their cellars and still provide wines free of allergenic residues. However, among the enological procedures under scrutiny, only bentonite fining proved to be capable of significantly reducing the allergenic residues.