This is the fraction of milk protein that makes up 80% of the protein. Casein provides a steady stream of amino acids over a longer period of time. As compared to whey protein, the soluble protein fraction in milk, casein takes 3 times longer to digest. This makes it an excellent bedtime protein or a good addition to your post-workout shake.
Take 20-40g between meals and/or before bedtime. Also consider adding 10-20g to the 20g of whey in your post-workout shake.