24th February 2020 Content supplied by: R-Biopharm AG
Eggs: a Challenge to Allergen Analysis
Eggs are very versatile foods and for many people an inherent part of the diet. However, they also are one of the most common allergy triggers worldwide.
Along with milk allergy, egg allergy is the most common allergy in childhood. Approximately 4 to 6 percent of children are affected. The egg allergy often develops during the first two years of life and disappears by itself during school age. Adults are rarely affected. In affected persons, eggs can cause allergic reactions even in the smallest quantities, leading to symptoms such as nausea, diarrhea, itching, swelling, rashes, shortness of breath or even anaphylactic shock. Triggers of the reaction are allergenic proteins in the egg.
There are more than 40 different proteins in a hen’s egg, but most allergic reactions are caused by only two proteins:
- Ovomucoid (Gal d 1): Along with ovalbumin, ovomucoid is the main allergenic protein in eggs. It is of high allergenic potential and heat-resistant. This means that people allergic to ovomucoid tolerate neither raw nor cooked or fried eggs.
- Ovalbumin (Gal d 2): Ovalbumin is heat-labile and decomposes at around 80°C. This is why people who are allergic to this protein often tolerate hard-boiled eggs or cake.
Cross-reactions between the different allergens in a hen’s egg and with eggs of other birds (e.g. quail eggs, goose eggs, duck eggs or seagull eggs) are possible. Allergy sufferers should get their tolerance tested by an allergist before consumption.
Eggs in the food industry
The most important part of allergy treatment is avoiding the allergenic substances in the diet. This often is a challenge as eggs can be used in a variety of dishes. They are not only an ingredient of pancakes, tiramisu or eggnog but are also contained in many foods where one would not necessarily expect to find them. Because of their technological characteristics, eggs are a popular additive in the food industry and are used in a variety of processed foods. For example, they serve as a binding agent in noodles and as an emulsifier in sauces and dressings. They add fluffiness to biscuits and meringues, and the carotenoids, in eggs, provide a delicate yellow colour. The egg white can be used for the fining of wine, and the lysozyme (E 1105) from the hen’s egg serves as a preservative due to its antimicrobial effect.
Detection of allergenic egg proteins
In order to protect allergy sufferers from unintentional consumption, eggs must be labelled as an allergen in the EU, the USA, Canada, Australia, China and many other countries. To ensure correct labelling in the food industry, test systems to determine the egg content in foods are available. However, these test systems usually only detect native egg protein. Processing of eggs leads to denaturation of the egg protein and alteration of the epitopes, which makes it difficult to detect them. In order to reliably detect eggs in all types of foods, R-Biopharm has developed the new and highly sensitive ELISA test RIDASCREEN® Egg (Art. No. R6411), which quantifies the allergic egg proteins ovomucoid and ovalbumin both in native and in processed form.
Date Published: 24th February 2020
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