Tiny particles of casein are suspended in a colloidal suspension in water to create milk. These particles of casein can be precipitated by dilute acids, so hydrochloric acid in the stomach or lactic acid formed as milk sours, so yoghurt can form. The casein precipitated in the stomach is digested by enzymes (active proteins) in the stomach (pepsin) and the large intestine (pancreatin), and by similar enzymes by micro-organisms, e.g. bacteria in hard cheese and moulds in blue cheese.
Casein is sometimes used in sports-drinks as a protein supplement.
Allergies to milk can result from reaction to casein within dairy products. Symptoms of a casein allergy can include: swelling lips, the mouth, tongue, or throat; skin reactions; nose congestion or runny nose.
- WebMD (undated) Casein Allergy Overview, accessed 21 June 2016 .
- Stobart, T. (1981) The Cook's Encyclopedia: ingredients & processes, Harper & Row. ISBN 0060141271.