How is the Elisa technique for detecting allergens in food?

Allergens are those substances that give way to allergic reactions, as a product of a response of the immune system to the appearance of foreign agents in the body. This reaction that occurs, does not happen in the same way in all people, occurs only with those sensitive to a specific antigen, which will make the immune system of the body captures them as dangerous or foreign, activating an inflammatory response to fight against them.

The immune system on contact with an allergen causes an exaggerated response that is evident in different organs of the human body. The allergen can come into contact with the body in various ways, for example, by ingesting or inhaling certain types of drugs or foods, or by contact with the skin, inducing serious symptoms such as rhinitis, sneezing, runny nose and even bronchial asthma.

Allergen screening uses a C-reactive protein test or immunochemical assays, such as the enzyme-linked immunosorbent assay, also known as the ELISA test, by its acronym. This test is a method of determining whether antibodies or foreign substances are present in a sample. The antibody is the protein produced by the immune system at the time antigens are detected.

ELISA test for allergens

The enzyme-linked immunosorbent assay known as the ELISA technique is an immunochemical assay that allows the detection of an antigen by means of an antibody that is linked to an enzyme through a product that can be detected, such as color change, which, through spectrophotometry, would enable the measurement of the antigen in the sample. An antigen is known as a foreign or toxic substance that causes a defensive response by the immune system.

The ELISA test is applied in various areas of research, human and veterinary medicine, as well as in the food industry, for the detection and quantification of antigens in a wide variety of samples. For example, in human medicine it is possible to know if a person has an autoimmune disease. In veterinary medicine, it makes it possible to detect and diagnose diseases affecting pets, livestock or birds, such as enzootic leukosis, bluetongue, swine fever and brucella, among others. In the food industry, it is used to detect allergens in food products for human and animal consumption, the most common to which it is applied are eggs, fish, milk, wheat, soy and nuts, among others.

In order to perform this technique, it is necessary to have the appropriate optical equipment, these are called spectrophotometers, which are responsible for measuring the amount of light that absorbs or transmits a sample for different wavelengths. Spectrophotometers consist of a light source, a monochromator and a detector.

Spectrophotometer and microplate reader

The spectrophotometer, is a equipment used in laboratories to measure the intensity of light that is absorbed when passing through a solution. This instrument is responsible for carrying out the ELISA test, measuring bacterial growth, DNA, RNA and protein analysis, among many other applications.

The microplate reader, on the other hand, is a type of spectrophotometer used mainly in the ELISA technique, it is characterized because it works in a limited range of wavelengths, between 400 and 750 nm, those necessary for the technique already mentioned. Works by detecting specific antigens or antibodies in a sample, the detected antigen will be immobilized in a solid phase because of antibodies, which directly or indirectly will produce a reaction, it will generate a producer that can be read in the spectrophotometer.

Kalstein spectrophotometer

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