We have made a few coffee beers. Once we used a cheap coffee by brewing a strong pot and adding to the boil. It turned out very acidic. The next beer we brewer we went with a little higher OG 1.070 and added 1/2 pound of Starbucks breakfast blend for the last 5 minutes of steeping the grains. That beer turned out great, but we could not taste the coffee as much as we would like. I'm interested in doing another one and I've been considering Kona coffee as it is bold but mild or chicory b/c a friend had good results. How do you make a great bold coffee beer that you can really taste the coffee but is not too acidic?
I would make a pot of really strong coffee in a french press or whatever (or espresso if you've got a machine). Ideally, add it to the secondary, because the primary fermentation will blow off a lot of the nice aroma.
I've done this in a stout before and used about 4 tablespoons of coffee in 1 pint cafetiere.
I use 2 methods....you can "dry bean" the beer in secondary using 4-8 poz. of coarsely cracked beans. That produces great aroma and a bit of flavor. For more coffee flavor, I add strong coffee at bottling or kegging time to taste. That's much easier to control than additions to the kettle or secondary.
Grind your coffee beans sometime during your boil. The later in the boil the better. Place the grinds into a muslin bag. When your boil is complete and the wort drops under 210F, hang the muslin bag of grind into the hot wort. I usually go for around 5-10 minutes. Remove muslin bag and start your chill. You definitely do NOT want to put the coffee in during the boil as it will put in all the acids.
Grounds can get pretty bitter in a long boil. I'd suggest adding either an extract or a good coffee liquor (I recommend Leopold Bros. if you can get it - no nasty chemicals like Kahlua). This method also lets you be really specific in the amount of flavor you want to add - draw out a cup or two from the secondary and add the extract until the balance is right, then scale the ratio up to the whole batch.
I made an Imperial Stout @ 9.2% and to steal Denny Cons term "dry beaned" one gallon of it onto 15.3 grams of coarsly ground beans for 2 days. The coffee flavor was very pronounced, and after 3 weeks was still strong. Probably helped that this was such a robust stout but it was still very potent coffee. maybe half this amount of coffe or only leave on secondary for a day.
You can get now get in the UK at least these coffee-bags (similar to tea bags but bigger and with coffee in them). They arrive sealed in foil and ready to go. I've placed these in the mix during the entire fermentation process. Because they are nicely in a bag they just come out when its time to bottle. Sorted, and great coffee stoat.
I made an espresso stout, where the espresso was added at bottling. I actually dissolved the sugar into the still-hot espresso; cooled it, then mixed both in. It turned out very well, with a nice amount of aroma and flavor.
Part-way through drinking it I discovered that pouring the yeast as well as the beer brings out much more of the flavor--it seems to be somewhat locked in the yeast layer of the bottle. To do this I poured all but ~1oz of beer, and swirled the bottle until the yeast had mixed into the remaining beer and poured it into the glass.