Enzyme Immunoassay for the quantitative determination of Egg White proteins in food.
Background: Hen’s egg (Gallus gallus) is very rich of proteins and represents an important food source for humans. While proteins of egg yolk only have minor allergenicity, many proteins of egg white are known to be allergenic. In addition to ovalbumin, ovotransferrin, lysozyme and livetin, ovomucoid represents the most important allergen. Unlike the other allergens ovomucoid is heat stable and can resist common production processes like baking. For allergic persons the consumption of egg white represents a critical problem. Already very low amounts of the allergen can cause allergic reactions, which may lead to anaphylactic shock in severe cases. Because of this, egg allergic persons must strictly avoid the consumption of eggs or egg containing food. Non-declared addition of egg in food is hazardous for allergic people. Crosscontamination, mostly in consequence of the production process is often noticed. The chocolate production process is a representative example. For the detection of egg white protein residues, sensitive detection systems are required. Egg White ELISA represents a highly sensitive detection system for egg white protein based on ovomucoid and is particularly capable of the quantification of egg white residues in pasta, bakery products, sausage and chocolate.
Description: The Egg White quantitative test is based on the principle of the enzyme linked immunosorbent assay. An antibody directed against ovomucoid is bound on the surface of a microtiter plate. Egg white (ovomucoid) containing samples or standards are given into the wells of the microtiter plate. After 20 minutes incubation at room temperature, the wells are washed with diluted washing solution to remove unbound material. A peroxidase conjugated second antibody directed against ovomucoid is given into the wells and after 20 minutes of incubation the plate is washed again. A substrate solution is added and incubated for 20 minutes, resulting in the development of a blue colour. The colour development is inhibited by the addition of a stop solution, and the colour turns yellow. The yellow colour is measured photometrically at 450 nm. The concentration of ovomucoid and with this the contration of egg white is directly proportional to the colour intensity of the test sample.
- The kit contains reagents for 96 determinations;
- Microtiter plate consisting of 12 strips with 8 breakable wells;
- Egg white protein standards: 0, 0.4, 1, 4, 10 ppm;
- ELISA reader at 450 nm;
- Standard range: 0.4 - 10 ppm;
- Sensitivity analytical: 0.05 ppm.