Design and characterization of a direct ELISA for the detection and quantification of leucomalachite green

Malachite green (MG), a member of the N-methylated triphenylmethane class of dyes, has long been used to control fungal and protozoan infections in fish. MG is easily absorbed by fish during waterborne exposure and is rapidly metabolized into leucomalachite green (LMG), which is known for its long residence time in edible fish tissue. This paper describes the development of an enzyme-linked immunosorbent assay (ELISA) for the detection and quantification of LMG in fish tissue. This development includes a simple and versatile method for the conversion of LMG to monodesmethyl-LMG, which is then conjugated to bovine serum albumin (BSA) to produce an immunogenic material. Rabbit polyclonal antibodies are generated against this immunogen, purified and used to develop a direct competitive enzyme-linked immunosorbent assay (ELISA) for the screening and quantification of LMG in fish tissue. The assay performed well, with a limit of detection (LOD) and limit of quantification (LOQ) of 0.1 and 0.3 ng g−1 of fish tissue, respectively. The average extraction efficiency from a matrix of tilapia fillets was approximately 73% and the day-to-day reproducibility for these extractions in the assay was between 5 and 10%

Effect of processing on the detectability of pecan proteins assessed by immunological and proteomic tools

The present study evaluates the effect of food processing on the antigenicity of pecan proteins as measured by enzyme-linked immunosorbent assay (ELISA). In addition, proteomic tools were used to identify potential pecan markers suitable for confirming the presence of pecan proteins in food and validating new methods developed to detect traces of the commodity. To assess the effects of processing on protein stability and antigenicity, pecan nuts were submitted to heat treatments and extracts were analysed by ELISA, sodium dodecyl sulphate polyacrylamide gel electrophoresis and Western blot. The ELISA method was able to detect pecan traces even after submitting the commodity to rigorous treatments, though these treatments affected the detectability to varying degrees. Proteomic assessment showed that the majority of pecan proteins were matched by homology to walnut proteins, which are more abundantly populated in the protein sequence databases. However, there were a few important exceptions: 7S vicilin, 11S legumin and putative allergen I1, unambiguously identified as pecan in origin. Interestingly, putative allergen I1 offered unique analytical advantages to be used as a pecan marker for validation and confirmation purposes.Fil: Polenta, Gustavo Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Tecnología de Alimentos; Argentina.Fil: Weber, Dorcas. Health Canada. Bureau of Chemical Safety; Canada.Fil: Godefroy Benrejeb, Samuel. Health Canada. Bureau of Chemical Safety; Canada.Fil: Abbott, Michael. Health Canada. Bureau of Chemical Safety; Canada

EDITORIAL "Food analytical methods", An integrated approach for food analysis

International audienc

Occurrence and risk assessment of sesame as an allergen in selected Middle Eastern foods available in Montreal, Canada

International audienceSesame allergy is a public health problem in many countries around the world. The purpose of this study is to determine the occurrence of sesame allergen in unlabelled or labelled free-sesame Middle Eastern foods with or without Precautionary Allergen Labelling (PAL) 'may contain' and estimate the risk incurred by the Canadian population allergic to sesame with a focus on products purchased in Middle Eastern grocery stores and bakeries in Montreal, Canada. A total of 571 samples were analysed to determine the level of sesame protein. Of the 571 samples analysed, 19% (109/571) contained sesame (results >LOQ) with concentrations of sesame proteins varying between 0.5 and 1,875 mg kg-1 and 35% (199/571) contained traces (a value between LOD and LOQ). Unpackaged products were found to present the highest proportion of sesame containing samples (36%). For packaged products, 16% (27/173) of samples with PAL and 3% (5/173) without PAL were found to contain sesame. A probabilistic approach was used to estimate the risk incurred by the Canadian consumers allergic to sesame. Our evaluation estimated that 33 to 308 allergic reactions may occur out of 10 000 individuals ingesting one type of bakery product contaminated at a level of 0.6-74 mg kg-1 sesame proteins. The incidence and level of sesame cross-contact reported in this study demonstrate that sesame allergic consumers could react if they ignore the precautionary allergen statements on product labels. Attention to sesame as a potential cross-contact agent and as a priority allergen calls for better management, given the growing interest in this ingredient to be included in food formulations. Enhanced risk management efforts must be coupled with targeted risk communication covering both producers and consumers as to the need to adopt and an approach for the application of precautionary allergen labelling based on risk

Validation procedures for quantitative gluten ELISA methods: AOAC allergen community guidance and best practices

The food allergen analytical community is endeavoring to create harmonized guidelines for the validation of food allergen ELISA methodologies to help protect food-sensitive individuals and promote consumer confidence. This document provides additional guidance to existing method validation publications for quantitative food allergen ELISA methods. The gluten-specific criterion provided in this document is divided into sections for information required by the method developer about the assay and information for the implementation of the multilaboratory validation study. Many of these recommendations and guidance are built upon the widely accepted Codex Alimentarius definitions and recommendations for gluten-free foods. The information in this document can be used as the basis of a harmonized validation protocol for any ELISA method for gluten, whether proprietary or nonproprietary, that will be submitted to AOAC and/or regulatory authorities or other bodies for status recognition. Future work is planned for the implementation of this guidance document for the validation of gluten methods and the creation of gluten reference materials.JRC.D.5-Standards for Food Bioscienc

Validation Procedures for Quantitative Food Allergen ELISA Methods: Community Guidance and Best Practices

This document provides supplement guidance on specifications for the development and implementation of studies to validate the performance characteristics of quantitative ELISA methods for the determination of food allergens. It is intended as a companion document to the "AOAC Official Methods of Analysis Appendix D: Guidelines for Collaborative Study Procedures to Validate Characteristics of a Method of Analysis" www.aoac.org (1). The guidance is divided into two sections: information to be provided by the method developer on various characteristics of the method, and implementation of a multi-laboratory validation study. Certain criteria included in the guidance are allergen-specific. Two food allergens: egg and milk are used to demonstrate the criteria guidance. These recommendations will be the basis of the harmonized validation protocol for any food allergen ELISA method, whether proprietary or nonproprietary, that will be submitted to AOAC and/or regulatory authorities or other bodies for status recognition. It should be noted that regulatory authorities may have their own particular requiretments for data packages in addition to the guidance in this document. Future work is planned for the implementation and validation of this guidance. This future work will also inclkude guidance specific to other priority allergensJRC.D.5-Food Safety and Qualit