Casein is the main protein in milk. This protein contains 80% of cow’s milk and the remaining 20% is whey protein. The casein protein contained in the milk was extracted by ultra filtration and no chemical was used. The result of this process is an increase in the amount of milk bioactive peptides that support immunity and lead to muscle growth. Casein protein has amino acids and is known as depleting protein. Myslana’s casein is a pure type of casein and does not contain whey as a late digested protein. Protein Isolated Milk Contains Whey and Casein. In cow’s milk, milk protein isolates make up about 80% of casein and 20% whey, making it an economically beneficial choice.