Melkschilfers

Melkschilfers, or milk skin, is a thin, creamy film that forms on the surface of milk when it is heated or boiled. The phenomenon is common in everyday cooking and in the preparation of hot beverages such as coffee or hot chocolate.

Formation and composition: When milk is heated, whey proteins such as beta-lactoglobulin and alpha-lactalbumin unfold and migrate toward the air–milk interface. There they coagulate and combine with fats and minerals to form a cohesive film. The resulting layer is mainly protein with traces of fat, minerals, and lactose. The thickness and presence of the skin depend on factors such as milk fat content and heating duration.

Occurrence and use: Melkschilfers are more likely to appear with higher-fat milks and longer heating times. The skin is edible and is often removed or stirred back into the milk, though some people appreciate its texture or use it in certain desserts or dairy preparations.

Prevention and removal: To reduce skin formation, heat milk slowly over low to medium heat, stir occasionally, and use a thick-bottomed pan to distribute heat more evenly. If a skin has formed, it can be skimmed off with a spoon or whisked back into the milk to reintegrate the proteins.