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Most of the rapid allergen test kits are enzyme-linked immunosorbent assay or ELISA-based tests that detect and measure a specific allergen in food samples. For example, this test could be use to screen for the presence of cross-contaminants in food products due to allergen residues. The test kits compare samples against known levels of allergen by a colorimetric reaction. Results are obtained within 2 to 3 hours and they can be quantified using optical instrumentation. Also, allergen strip tests screen samples for food allergen at specific concentration in a few minutes (10-20 min). Both the ELISA test kits and the strip tests require a minimal amount of training and equipment and are commonly used.
Commercial testing for egg (ovalbumin, ovomucoid), peanuts (Ara h1, Ara h2), wheat (gliadin), hazelnut, milk (casein, b-lactoglobulin), crustacean (tropomyosin), and soy residues are available through several manufacturers (ex: Biotrace International, Neogen Corporation, R-Biopharm, Elisa Systems, etc).
Microbial testing provides the detection and quantification of pathogens and spoilage microorganisms in a variety of products. Not only do these analyses allow processors to address food safety issues if pathogenic bacteria are detected, but they also predict the shelf life of a product when evaluating spoilage microorganisms.
A list of suppliers of microbial rapid tests is provided on the 'Analytical Testing' - supplier section.
Culture techniques, which are commonly used in microbiology, rely on the growth of microorganisms under specific conditions (ex: time, temperature, oxygen content, pH and pressure) in liquid or on solid media containing nutrients. Culture methods using standard media require between 1 to 7 days for detecting the presence of microorganisms. Often, an enrichment step and/or a confirmation procedure is required before and after microbial detection, respectively.
Rapid methods for microbial testing assess the microbial population through the metabolic activity of the cells. Such techniques include chromogenic media, colorimetry, ATP (adenosine triphosphate) determination, protein detection and biochemical kits.
Enzyme immunoassay (EIA), also known as enzyme-linked immunosorbent assay (ELISA), is a common technique for antibody-based detection of microorganisms. This method ensures sensitivity and specificity for pathogen detection. Results can be interpreted visually (qualitatively) or using an instrumental read-out (quantitatively). Test kits for the detection of Salmonella, Listeria, Campylobacter, E. coli 0157:H7, Pseudomonas, Staphylococcus aureus are commercially available (ex: BioControl Systems, Bio Trace, etc).
Compared to antibody-based methods, there are relatively few commercialized versions of nucleic acid-based methods.
Mycotoxins (toxins produced by certain species of mold) such as aflatoxin, deoxynivalenol (DON), fumonisin, ochratoxin, T-2 toxin, zearalenone and histamine; as well as bacterial toxins (ex: bacillus, staphylococcus enterotoxins) can be detected by ELISA based test kits. These kits are commercially available. (e.x. R-Biopharm, Biotrace International, Neogen Corporation, Elisa Technologies). A list of these suppliers is provided in the 'Analytical Testing Suppliers' section.
For more information, email the CVO/Food Safety Knowledge Centre or call 204-795-8418 in Winnipeg.