More and more people suffer from milk allergies. It is important to note that milk allergy is not the same as lactose intolerance. The cause of lactose intolerance is a deficiency of an enzyme that degrades lactose (milk sugar). Milk allergy, on the other hand, is a true food allergy which is caused by allergenic constituents of milk proteins.
Cow’s milk contains several proteins that have an allergic potential. The most important ones are casein and ß-lactoglobulin.
One of the major allergens in milk is casein. It plays an important role in cheese production and is mainly present in cheese, quark, yoghurt, cream and butter. Moreover, casein is present in bakery goods, chocolate, wine and meat products. Since the protein casein is not specific for cow’s milk, it is also present in sheep’s milk, goat milk and other types of milk.
ß-lactoglobulin is a whey protein. It is present in fresh milk and in hydrolysed dairy products such as baby food. The allergy to ß-lactoglobulin usually occurs in children, while adults are more often allergic to casein. Since ß-lactoglobulin is not heat-stable, allergic people often tolerate cooked dairy products. In addition, products made from sheep or goat milk can be well tolerated.
As an allergen, milk is subject to labelling in many countries. In order to ensure a product that is safe for allergic people, it is important to test food and surfaces during the production process.