Casein is a protein precipitated from milk generally used for the bases of cheese. It also accounts for nearly 80% of proteins in cow milk and cheese.
Slower digestion is always better for the human system. While rapid protein absorption is desirable immediately before or after exercise, delayed release is probably more beneficial throughout the remainder of the day.
Casein proteins are pH sensitive and gel in the acidic environment of the stomach. As a result, it can take more than twice as long for caseins to be broken down into the amino acid subcomponents than whey and other proteins. Caseins are anti-catabolic or muscle-protecting proteins and can be a great addition to your diet to reach your workout goals.