Enzyme immunoassay for the quantitative determination of beta-Lactoglobulin in food.
Background: Bovine milk belongs to the most important allergenic food ingredients especially for children. Already very low amounts of bovine milk can cause allergic reactions, which may lead to anaphylactic shock in severe cases. Because of this, milk allergic persons must strictly avoid the consumption of milk or milk containing food. In particular the presence of hidden milk proteins such as in sausage, cookies, convenience food or beverages represent a critical problem for milk allergic persons. According to EU Directive 2003/89/EG the addition of bovine milk has to be labeled. For the detection of bovine milk in foodstuffs sensitive detection systems are required. Approximately 20% of bovine milk proteins are whey proteins. The main fraction of whey proteins consists of the heat-stable allergen beta-lactoglobulin. The beta-Lactoglobulin ELISA represents a highly sensitive detection system and is particularly capable of the identification and quantification of bovine milk residues in cookies, cereals, sausage, orange juice, wine, soy products and chocolate.
Description: The beta-Lactoglobulin ELISA quantitative test is based on the principle of the enzyme linked immunosorbent assay. An antibody directed against beta-lactoglobulin is bound on the surface of a microtiter plate. beta-Lactoglobulin 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 beta-lactoglobulin 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 beta-lactoglobulin 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;
- beta-Lactoglobulin Standards: 0, 10, 40, 100, 400 ppb;
- ELISA reader at 450 nm;
- Standard range: 10 - 400 ppb;
- Sensitivity analytical: 1.5 ppb.