A Faster, Simpler Tool for Detecting Peanut Contamination

More than four million people in the United States are known to have a food allergy, with an allergy to peanuts being one of the most common and the most serious. According to Anne Munoz-Furlong, president of the Food Allergy Network, "Peanut allergy leads to the most hospitalization and fatal and near fatal allergic reactions to food."

There are a variety of ways food can unintentionally pick up traces of peanut. One example is if a shipment of loose corn is sent in the same truck as an earlier shipment of peanuts. The corn could become contaminated with peanut dust and end up in the corn product. But a more likely scenario is that a food manufacturer, for reasons of economy and practicality, has used the same equipment to process two different products. Processing foods on the same equipment is a common and necessary practice.

Even though processors clean equipment carefully to avoid this kind of cross contamination, it is difficult to be a 100% certain that all residual peanut material has been eliminated. Which is what led a number of food processors to approach the University of Nebraska's Institute of Agriculture and National Resources. In 1995, with the support of 17 food processors, the university launched the Allergy Research and Resource Program to work with industry on food allergy issues. Which is where Drs. Steve Taylor and Sue Hefle began using rabbits to develop antibodies to peanut components, and developing their long version of a test method for peanut.

Based on that work, Neogen Corp. (Lansing, MI) has developed a fast, easy-to-use version of the test designed for manufactures on the plant floor. The test kit provides a relatively simple way to detect the unintentional presence of peanut components in products. Called Veratox for Peanut Allergen, the test is a sandwich enzyme-linked immunosorbent assay (S-ELISA) that allows the user to obtain exact concentrations of peanuts in parts per million.

The Procedure

Free allergen, in the sample and controls, is allowed to react with the specific antibody coating in the microwells. After a wash step, enzyme-labeled antibody (conjugate) is added to the antibody wells and is allowed to attach to the bound allergen, forming an "antibody sandwich" around the allergen.

1.	Add 150 µL controls and samples to transfer wells.	2.	Transfer 100 µL to the antibody wells. Incubate for 10 minutes.
3.	Dump liquid from antibody wells.	4.	Wash wells thoroughly 5 times with washing solution.
5.	Tap out water on absorbent paper towel.	6.	Transfer 100 µL conjugate from reagent boat to antibody wells using 12-channel pipettor. Incubate for 10 minutes.
After another wash step, substrate is added which reacts with the conjugate to produce blue color. More blue color means more allergen is present.
7.	Repeat steps 3-5 by dumping out the liquid, thoroughly washing the wells and tapping dry.	8.	Transfer 100 µL substrate from reagent boat to antibody wells using 12-channel pipettor. Incubate for 10 minutes.
9.	Transfer 100uL red stop from reagent boat to antibody wells. Read results in a microwell reader.
The test is read in a microwell reader to yield optical densities. The control optical densities used to form the standard curve and the sample optical densities are plotted against the curve to calculate the exact concentration of allergen. The test, for which the user requires only a minimal amount of training, takes 30 minutes to perform and provides results for up to 38 samples. Previously, processors had to rely on a test method that took days to complete in a laboratory setting. Neogen Corporation is a Lansing, MI-based company that develops and markets products and services dedicated to food and animal safety. The peanut test is the first commercialization in ongoing research by the University of Nebraska's Institute of Agriculture and Natural Resources food allergy team. Tests for egg and casein, a milk component, should be commercialized in 1999. Tests for soybeans and tree nuts are in the works. For more information contact: Neogen Corp., 620 Lesher Place, Lansing, MI 48912. Tel: 800-234-5333. Fax: 517-372-2006.