Carmen Diaz-Amigo

Accuracy of ELISA Detection Methods for Gluten and Reference Materials: A Realistic Assessment

The determination of prolamins by ELISA and subsequent conversion of the resulting concentration to gluten content in food appears to be a comparatively simple and straightforward process with which many laboratories have years-long experience. At the end of the process, a value of gluten, expressed in mg/kg or ppm, is obtained. This value often is the basis for the decision if a product can be labeled gluten-free or not. On the basis of currently available scientific information, the accuracy of the obtained values with commonly used commercial ELISA kits has to be questioned. Although recently several multilaboratory studies have been conducted in an attempt to emphasize and ensure the accuracy of the results, data suggest that it was the precision of these assays, not the accuracy, that was confirmed because some of the underlying assumptions for calculating the gluten content lack scientific data support as well as appropriate reference materials for comparison. This paper discusses the issues of gluten determination and quantification with respect to antibody specificity, extraction procedures, reference materials, and their commutability.

Towards a Comprehensive Validation of ELISA Kits for Food Allergens. Case 2—Milk

There are several enzyme-linked immunosorbent assay (ELISA) kits in the market that have been proven to be useful for the determination of egg in foods. However, inconsistent results that are obtained when different kits are used make the selection of one kit over another very difficult. Two different approaches were used to help understand why results vary among kits. Different kits were used to analyze spiked egg material [NIST reference material (RM) 8445] in wheat flour (raw ingredients) and cookies containing egg as an ingredient baked for different periods of time (processed food). These results were compared with immunoblotting using conjugated antibodies from the commercial kits to determine the antibody specificity and sample extraction efficiency. ELISA results can be difficult to compare because reporting units differ among kits. Results from both ELISA and immunoblotting are in agreement regarding the decreased detection of proteins in baked cookie extracts. Moreover, immunoblotting showed that this reduction is due to reduced protein content in these extracts. However, a properly selected extraction solution may help improve the solubility of certain egg proteins in processed foods. Harmonization of the reporting unit system along with the use of a common reference material is recommended as the path forward in the standardization of detection methods for food allergens. This would assist the end user in making an informed decision regarding the selection of the most appropriate kit for his or her purpose.

Stakeholders’ Guidance Document for Consumer Analytical Devices with a Focus on Gluten and Food Allergens

Until recently, analytical tests for food were performed primarily in laboratories, but technical developments now enable consumers to use devices to test their food at home or when dining out. Current consumer devices for food can determine nutritional values, freshness, and, most recently, the presence of food allergens and substances that cause food intolerances. The demand for such products is driven by an increase in the incidence of food allergies, as well as consumer desire for more information about what is in their food. The number and complexity of food matrixes creates an important need for properly validated testing devices with comprehensive user instructions (definitions of technical terms can be found in ISO 5725-1:1994 and the International Vocabulary of Metrology). This is especially important with food allergen determinations that can have life-threatening consequences. Stakeholders-including food regulators, food producers, and food testing kit and equipment manufacturers, as well as representatives from consumer advocacy groups-have worked to outline voluntary guidelines for consumer food allergen- and gluten-testing devices. These guidelines cover areas such as kit validation, user sampling instructions, kit performance, and interpretation of results. The recommendations are based on (1) current known technologies, (2) analytical expertise, and (3) standardized AOAC INTERNATIONAL allergen community guidance and best practices on the analysis of food allergens and gluten. The present guidance document is the first in a series of papers intended to provide general guidelines applicable to consumer devices for all food analytes. Future publications will give specific guidance and validation protocols for devices designed to detect individual allergens and gluten, as statistical analysis and review of any validation data, preferably from an independent third party, are necessary to establish a devices fitness-for-purpose. Following the recommendations of these guidance documents will help ensure that consumers are equipped with sufficient information to make an informed decision based on an analytical result from a consumer device. However, the present guidance document emphasizes that consumer devices should not be used in isolation to make a determination as to whether a food is safe to eat. As advances are made in science and technology, these recommendations will be reevaluated and revised as appropriate.

European Regulations for Labeling Requirements for Food Allergens and Substances Causing Intolerances: History and Future

Food allergens and intolerances have been diagnosed by doctors for decades, but have received heightened attention in the last two decades because diagnosis and awareness have increased. Consequently, regulators in many jurisdictions have addressed this topic by introducing labeling requirements for substances causing allergies and intolerance reactions in affected individuals. Mandatory labeling of food allergens allows persons suffering from these to make informed choices. However, regulations in some geographic areas have resulted in significant problems for manufacturers as well as consumers. This has been mainly due to frequent changes and amendments, and it has been difficult for all stakeholders to follow and understand the status quo of legislation. The present paper describes the development of European directives and regulations for the labeling of food allergens and intolerances to substances like gluten over the past decades and provides an outlook of what can reasonably be expected to change in the coming years. It also identifies existing gaps, like a lack of threshold levels for adventitious contamination and consequently a proliferation of precautionary allergen labeling, which neither benefits the consumer nor the food industry in its current form.

Food Allergens: A Regulatory/Labelling Overview Including the VITAL Approach

Food allergens have received increased attention from consumers and regulators around the globe alike. Numerous countries have introduced labelling requirements for food allergies to allow the consumer to make informed choices. However, the regulations of different countries are often not harmonized and have significant gaps. Examples are Europe, requiring the labelling of 14 groups of substances causing food allergies and intolerances and Japan with its seven allergens requiring mandatory labelling and a further 20 which are recommended to be labelled. Both countries deviate from the “big eight” list of food allergens as defined in Codex Alimentarius STAN 1-1985. Beyond inconsistencies in the labelling requirements for food allergens among countries, there are often regulatory gaps in how to deal with unintended allergen contamination of foods. Here, guidelines and labeling thresholds are often missing. This article will highlight regulations and regulatory gaps for food allergens of selected countries.

Molecular Biological and Immunological Techniques and Applications for Food Chemists: Popping/Techniques for Food Chemists

CONTRIBUTORS. PREFACE. PART Ia MOLECULAR BIOLOGICAL METHODS: TECHNIQUES EXPLAINED. 1. Molecular Biology Laboratory Layout (Rainer Schubbert). 2. Polymerase Chain Reaction (Hermann Broll). 3. Quantitative Real-Time PCR (Hermann Broll). 4. Polymerase Chain Reaction Restriction Fragment Length Polymorphism Analysis (Klaus Pietsch and Hans-Ulrich Waiblinger). 5. Single-Stranded Conformation Polymorphism Analysis (Hartmut Rehbein). 6. Sequencing (Rainer Schubbert). PART Ib MOLECULAR BIOLOGICAL METHODS: APPLICATIONS. 7. Meat (Ines Laube). 8. Genetically Modified Organisms (Bert Popping). 9. Detection of Food Allergens (Carmen Diaz-Amigo and Bert Popping). 10. Offal (Neil Harris). 11. Aquatic Food (Hartmut Rehbein). PART IIa IMMUNOLOGICAL METHODS: TECHNIQUES EXPLAINED. 12. Antibody-Based Detection Methods: From Theory to Practice (Carmen Diaz-Amigo). PART IIb IMMUNOLOGICAL METHODS: APPLICATIONS. 13. Animal Specification in Speciation (Bruce W. Ritter and Laura Allred). 14. International Regulatory Environment for Food Allergen Labeling (Samuel Benrejeb Godefroy and Bert Popping). 15. Japanese Regulations and Buckwheat Allergen Detection (Hiroshi Akiyama, Shinobu Sakai, Reiko Adachi, and Reiko Teshima). 16. Egg Allergen Detection (Masahiro Shoji). 17. Soy Allergen Detection (Marcello Gatti and Cristina Ferretti). 18. Milk Allergen Detection (Sabine Baumgartner). 19. Gluten Detection (Ulrike Immer and Sigrid Haas-Lauterbach). 20. Nut Allergen Detection (Richard Fielder, Warren Higgs, and Katie Barden). 21. Fish Allergen Detection (Christiane Kruse Faeste). 22. Lupin Allergen Detection (Christiane Kruse Faeste). 23. Mustard Allergen Detection (Anne E. Ryan and Michael S. Ryan). 24. Celery Allergen Detection (Charlotta Engdahl Axelsson). INDEX.