I just finished a coffee stout and did both. Grind the coffee a bit coarser than you would for
your drip machine and just put it in the secondary, it will drop out when it gets saturated with
the beer. In a week it will be on the bottom. For adding brewed coffee, cold brew some coffee
by leaving it in cold water overnight then add to bottling bucket or keg. Have a taste and you can
adjust. This reduces the amount of oils from the coffee and does not hurt your head retention as
much.
this. you get the coffee character but not any acrid harshness that can happen from drip or any hot-pressed coffee.
Just to give him an idea of the process, this is what I recall, but please correct:
-combine 1 quart of cold (preferably filtered) water with 10 or so tablespoons of ground coffee in a sealable sanitized clean container.
-place in fridge for 48 hours (or at least 12 hours)
-run through coffee filter into another sanitized container
-add to taste*
*I recommend pulling 8oz of beer from your secondary, splitting into 4 2oz samples. Add/mix increasing amounts of the coffee extract to each and taste (I do it with a ‘panel’ and ask which they prefer as well. Then scale up and add the appropriate amount to the finished beer (I only add 3/4 of that amount or so, as you can always add more)
Go with Pietro’s advice. I have done two coffee stouts, using Don Osborn’s recipe. I used a French press both times, and used the same amount of beans both times (6 oz). Each time, I brewed two 32-oz pots of strong coffee and added it at bottling time. I preboiled the water to drive out oxygen.
The second time, I did a cold steep for 12 hours. Even though the amount and variety of beans were the same, the coffee flavor was MUCH stronger in the cold-steeped batch. A bit too strong for my tastes. The first time (hot steeping) was perfect.
So Pietro is right - you should definitely set up a little tasting flight and mix different ratios in there, then scale up to the whole batch. It’s a great time for coffee stouts!