milk is composed of many proteins. the main groups are casein and whey proteins. Casein are very digestible when compared to other food proteins, making it a very important human food. Casein is negatively charged in its natural state. This negative charge permits the casein to disperse in milk. When you acidify milk, its pH is allowed to reach 4.6, which brings casein to its isoelectric point. the isolectric point is point at which all charges are neutral. when casein loses its negative charge, it precipitates as