To pasteurize, you just boiled it for a while?
Don't boil it. Just as with your mash you'll extract tannins above 170. I shoot for 165 for 15-20 minutes. HTST (high temp short time) pasteurization requires 161.5 for at least 15 seconds.
Also, do be aware that coffee beans have a lot of oils in them, so it may affect head retention.

