Chicken eggs are used extensively as an excellent source of dietary proteins. These proteins have many functional properties, making them valuable food ingredients. However, eggs are a frequent cause of
food hypersensitivity, especially in children. Of major concern to food processors is the inadvertent cross-contact of food products with allergenic residues, which could result in potentially life-threatening
reactions in those with a food allergy. The aim of the present study was to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of undeclared egg residues in foods. Commercially purified
ovalbumin (OVA) and dehydrated egg white solids were used as antigens to induce antibodies in rabbits and goats. Reference pasta standards and various food samples were extracted, then clarified by centrifugation.
Goat anti-egg white antibodies were used as the capture reagent, nonspecific sites were blocked with gelatin, then standard and sample extracts were added. Rabbit anti-OVA antibodies were used as detector
antibodies, followed by addition of commercial goat anti-rabbit IgG antibody labeled with alkaline phosphatase and subsequent substrate addition. Twenty brands of egg-free pasta (two lots each) were analyzed
using the ELISA. Fourteen common pasta ingredients were also evaluated for cross-reactivity problems in the method. The detection limit of the assay was 1 ppm spray-dried whole egg. Fifty-five percent (22
samples) of the egg-free pasta samples tested positive for the presence of undeclared egg residues, with values ranging from 1 to > 100,000 ppm. Minimal crossever, reactivity was encountered in general,
but portobello mushrooms and basil caused some minor matrix effects. This sandwichtype ELISA method can be used to detect undeclared egg residues in processed foods and to evaluate industrial clean-up operations.
Document Type: Research Article
Food Allergy Research and Resource Program, University of Nebraska-Lincoln, Department of Food Science and Technology, Lincoln, Nebraska 68583-0919,
Food Allergy Research and Resource Program, University of Nebraska-Lincoln, Department of Food Science and Technology, Lincoln, Nebraska 68583-0919, USA
Publication date: November 1, 2001
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