The Food Allergy Research & Resource Program develops assays for the detection of residues of allergenic foods that might contaminate other foods. Currently, FARRP's research is focused on immunoassays, specifically Enzyme-Linked ImmunoSorbent Assays (ELISA).
Food allergens are naturally-occurring proteins that exist in the foods. While foods contain literally millions of different proteins, only a few of these proteins are allergens.
In the FARRP ELISA format, antisera are developed in animals such as goats, rabbits, sheep, or mice using crude extracts of allergenic foods or specific proteins from allergenic foods as the antigens. Immunoglobulin G (IgG) antibodies against certain proteins in the crude extracts are produced. While the IgG antibodies may be directed at proteins that are not allergens, FARRP believes that the detection of any protein or group of proteins from the allergenic food signifies the presence of the co-existing allergenic proteins also. Thus, the FARRP ELISAs detect residues of allergenic foods rather than food allergens. Nevertheless, these ELISAs are quite useful for detecting allergenic food residues arising from such food industry practices as using shared equipment or using rework.
FARRP assessed its ELISA tests for their ability to detect residues of allergenic foods in a variety of food matrices. FARRP does this carefully by preparing food products containing known levels of the allergenic food in question, then subjecting them to the assay. Such "real-world" evaluations are essential when seeking quantitative results.
FARRP has also tested its ELISAs to assure that the tests are specific for the food in question. Antibodies are usually highly specific to certain proteins. Cross-reactions, however, sometimes may occur, especially with proteins from closely-related foods. FARRP constructs its ELISAs using antisera that allow the highly specific detection of one particular food in a variety of other food matrices.
ELISAs typically have detection limits in the low parts per million (ppm) range. The detection limit can be affected in some cases by the food matrix.
Consumers with food allergies can react to very small amounts of the offending food contaminating another food. Levels below 10 ppm, however, are likely to be below the threshold limit for food-allergic individuals. It is important to note, however, that the precise threshold for reactions among food-allergic individuals has yet to be firmly established. While ELISA tests are very sensitive, due to variations in food ingredient and commodity compositions, levels detected below 10 ppm should be considered for research purposes.
FARRP has several ELISAs in various stages of development. FARRP chose these foods because they are among the most commonly allergenic foods in one or more areas of the world. Once developed, FARRP actively works with industry partners to commercialize the ELISAs into test kits.
- Taylor, S. L. 1992. Chemistry and detection of food allergens. Food Technol. 46(5):146-152.
- Nordlee, J. A. and S. L. Taylor. 1995. Immunological analysis of food allergens and other food proteins. Food Technol. 49(2):129-132.
- Taylor, S. L. and J. A. Nordlee. 1996. Methods for the detection of food allergens. Food Technol., 50 (5):231-234, 238.
- Hlywka, J. J., S. L. Hefle, and S. L. Taylor. 2000. A sandwich enzyme-linked immunosorbent assay for the detection of almonds in foods. J. Food Prot. 63:252-257.
- Hefle, S. L., E. Jeanniton, and S. L. Taylor. 2001. Development of a sandwich enzyme-linked immunosorbent assay for the detection of egg residues in processed foods. J. Food Prot. 64:1812-1816.
- Chen, L., S. L. Hefle, S. L. Taylor, I. Swoboda, and R. E. Goodman. 2006. Detecting fish parvalbumin with commercial mouse monoclonal anti-frog parvalbumin IgG. J. Agric. Food Chem. 54:5577-5582.
- Van Hengel, A. J., E. Anklam, S. L. Taylor, and S. L. Hefle. 2006. Analysis of food allergens. Practical applications. In: Food Toxicants Analysis, ed. Y. Pico, Elsevier, Amsterdam, Netherlands, pp. 189-230.
- Lee, P. W., S. L. Hefle, and S. L. Taylor. 2008. Sandwich enzyme-linked immunosorbent assay
(ELISA) for detection of mustard in foods. J. Food Sci. 73:T62-T68.
- Kaw, C. H., S. L. Hefle, and S. L. Taylor. 2008. Sandwich enzyme-linked immunosorbent assay (ELISA)
for the detection of lupine residues in foods. J. Food Sci. 73:T135-T140.
- Niemann, L., S. L. Taylor, and S. L. Hefle. 2009. Detection of walnut residues in foods using an enzyme-linked
immunosorbent assay. J. Food Sci. 74:T51-T57.
- Taylor, S. L., J. A. Nordlee, L. M. Niemann, and D. M. Lambrecht. 2009. Allergen immunoassays - considerations for use of naturally incurred standards. Anal. Bioanal. Chem. 395:83-92.
- Panda, R., S. L. Taylor, and R. E. Goodman. 2010. Development of a sandwich enzyme linked immunosorbent assay (ELISA) for detection of buckwheat residues in food. J. Food Sci. (In Press).