Michael Abbott

Multi-allergen screening immunoassay for the detection of protein markers of peanut and four tree nuts in chocolate.

A multiresidue enzyme immunoassay was developed to check for the presence of markers of peanut, hazelnut, almond, cashew and Brazil nuts in a single run. The assay was designed under the competitive indirect format and adapted for screening purposes applied to chocolate samples. The limit of detection for this assay was below 1 µg g−1 protein for each allergenic food. In most cases, the high specificity of the antibodies used allowed the identification of each particular allergenic food with no possible confusion. This assay was proven to be useful as part of an analytical procedure involving the identification of the unknown allergenic food among peanut and other tree nuts in recalled samples before the application of a quantitative technique to determine the level of cross-contamination.

Development and Validation of an Indirect Enzyme Immunoassay for the Detection of the Herbicide Isoproturon in Water Matrices

Abstract An indirect enzyme immunoassay (EIA) for the detection of the phenylurea herbicide isoproturon is described. The specific antibodies did not cross-react with other structurally related compounds. The concentration of isoproturon that inhibits 50% of antibody-antigen binding (IC50) was 0.64 ng/mL. The sensitivities were 0.07 ng/mL (IC80) and 0.02 ng/mL (IC90) respectively, when the crude serum was used in the assay. Matrix effects were observed when river water samples were analyzed showing recoveries as high as 150%. The IC50 was increased to 0.81 ng/mL. To overcome these difficulties, a novel method of anatibody purification was developed to reduce the heterogeneity of the medium when the test was performed with complex surface water matrices. This technique involved the extraction of the specific anti-isoproturon antibodies from the crude anti-serum. The refined fraction gave an IC50 not higher than 0.29 ng/mL and an IC90 of 0.01 ng/mL, when assayed with river water samples. The method was vali...

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%.

Celiac Disease and Gluten-Free Oats: A Canadian Position Based on a Literature Review

This paper provides an overview of the latest scientific data related to the safety of uncontaminated oats (<20 ppm of gluten) in the diet of individuals with celiac disease (CD). It updates the previous Health Canada position posted on the Health Canada website in 2007 and a related paper published in 2009. It considers a number of recent studies published between January 2008 and January 2015. While recognizing that a few people with celiac disease seem to be clinically intolerant to oats, this review concludes that oats uncontaminated by gluten-containing cereals (wheat, rye, and barley) can be safely ingested by most patients with celiac disease and that there is no conclusive evidence that the consumption of uncontaminated or specially produced oats containing no greater than 20 ppm gluten by patients with celiac disease should be limited to a specific daily amount. However, individuals with CD should observe a stabilization phase before introducing uncontaminated oats to the gluten-free diet (GFD). Oats uncontaminated with gluten should only be introduced after all symptoms of celiac disease have resolved and the individual has been on a GFD for a minimum of 6 months. Long-term regular medical follow-up of these patients is recommended but this is no different recommendation to celiac individuals on a GFD without oats.

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.

Foreword to the Special Issue on Food Allergen Methodologies

Food Allergy is an on-going public health problem and continues to be a challenge to both the clinical community and the food industry. Food safety regulators, industry, and consumer groups are working towards the development of the appropriate risk assessment and risk management procedures to prevent the inadvertent consumption of allergenic ingredients by allergic individuals, while not unduly impairing their choice. The availability of analytical methods to detect and determine levels of markers of priority allergens in foods are of the utmost importance to support standard setting initiatives, the development of compliance and enforcement activities, as well as to provide guidance to industry on implementation of quality control practices and ensuring the effectiveness of allergen-related sanitation techniques. Beginning in October of 2003, Health Canadas Food Directorate has hosted a series of workshops on Food Allergen Methodologies. These workshops aim to gather scientists, chemists, analysts, and other representatives from government agencies, academia, industry, and consumer associations, to discuss issues related to the detection, identification, characterization, and control of allergens in foods. Truly international in scope, these workshops have attracted participation from around the world, including European nations, Australia, Hong Kong, Japan, USA, as well as from all across Canada. This special issue of food analytical methods is dedicated to reporting on the fifth workshop on food allergen methodologies, which took place in Halifax, Nova Scotia, Canada, from May 11–14, 2008. Health Canadas Food Directorate, along with the Food Allergy Research and Resource Program of the University of Nebraska, USA, coorganized the event with support from MoniQA (Monitoring and Quality Assurance in the food supply—an international Network of Excellence cofunded by the European Union). The workshop was an opportunity to enhance consultation, information exchange, and to foster harmonization of method validation in the area of food allergens. The event gathered scientists, analysts, and other representatives from government agencies, university, and Food Industry. This special issue presents some highlights of the workshop which discussed method development for specific food allergens, method validation requirements, international initiatives such as that supported by the MoniQA network of excellence, as well as surveys aiming to determine levels of allergens in correspondence with labeling. The guest editors of this special issue would like to thank workshop participants and authors for making this workshop a success and for their contribution to this special issue. S. B. Godefroy Health Canada, Food Directorate, Sir Frederick Banting Research Centre, Ottawa, Canada e-mail: Samuel_Godefroy@hc-sc.gc.ca