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Development of Detection Methods for Allergenic Foods

The Food Allergy Research & Resource Program is developing assays to detect allergenic food residues 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 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 protein from the allergenic food signifies the presence of the allergenic proteins. 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 processing equipment or using rework.

FARRP assesses its ELISA tests for their ability to detect residues of allergenic foods in a variety of food matrices. FARRP does this by carefully 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 also has 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.

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 consumers has yet to be firmly established. While ELISA tests are very sensitive, due to variation in food additive and commodity compositions, levels 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 the average U.S. diet. Once developed, FARRP actively works with industy partners to commercialize them into test kits.