I assume you are refering to Hydrolyzed protein. Either of them, whey or caseinate, are going to taste extremely bitter. The best you can do, to resduce bitterness, is to use a higher molecular weight formula (expressed in daltons) which has a trade off of not having a high concentration of peptides as the better hydrolyzed protein, with a lower molecular weight which is more digestable and contains more protein peptides per serving.
It is recommended not to use straight, but in a whey protein formula to mask the taste. Of course, http://www.proteinfactory.com is the place to become more educated about protein, and have access to the best protein and formulas in the world.