I did a lot of reading before my first coffee porter and now, after multiple batches, it's pretty darn good...my friends tell me (especially female coffee lovers). Here are some thoughts. (BTW be sanitary but don't worry...I've never introduced infection this way)
2 days before bottling:
1) Preboil the water so it's de-oxygenated, then chill about 2 quarts
2) add 1/2 pound finely ground fresh bold coffee (I use dark peruvian) and cover
3) leave alone for 48 hours in a cool/cold place (fridge) but go ahead and swirl from time to time
4) allow to settle then either use a (somewhat sanitized) coffee press to further reduce chunkiness (tech term?) or filter paper (slow and boring, but probably worth it if you're doing a light beer)
5) on bottling day, draw ("sacrifice") about 16 ounces while siphoning but before adding sugar
6) now this is the tough but fun part. Do the math. 2 quarts on 5 gallons (20 qts) means maximum 2:20 ratio (1:10) So make 3 or 4 samples with different ratios coffee:beer. This needs to be pretty precise because once you decide which sample is the right ratio you'll be scaling up to 5 gallon and pouring it in the bottling bucket.
7) have fun running taste comparisons with at least one germ-free friend and pick the taste you want.
So let's say you do 1:10, 1:20 and 1:30 (I suggest three 5-ounce beers and add 1/2 oz, 1/4 oz and 1/6 oz...BTW 1 fluid oz = 6 tsp )and decide you like the lightest (1:30)...more math...you need to add 1/30th of 20 quarts of coffee to the 20 quarts of beer. That's about 21 ounces of cold-brewed coffee (20x32/30). OK...so precision might be overrated...get it close.
A couple more things.
-After conditioning, store as cold and as long as possible before serving...especially if you've made a light-colored beer. A lot of dark dust will settle out eventually.
-My coffee porter really ages well...it's just tough to save it for a year...but it's really mellow then
-Don't throw away leftover coffee...make a nice iced coffee...learn how smooth cold-brewed coffee can be.
-Sometimes we put in 2/3 of the coffee, bottle half the batch, then add the other 1/3. That way half the batch is twice as strong coffee-wise (more math). Sometimes I'll bottle a few without any coffee as "control" specimens.
-excellent barter opportunity...my friend has a coffee company so he comes over to bottle and I trade a case (24) for 3# of coffee...I get 2.5# high quality coffee out of the deal (the other 1/2# is in the beer)
Sorry for the long post.
Please read my quotes below and have fun! Hope this helps.
PS I essentially use Palmer's Port O Palmer Porter recipe pg. 223 of my copy of How to Brew.
