Hey @strumelia.
Yes, the grounds sit in the water for 48 hours. The contraption that I have came with a recipe book that suggests 12 hours is enough, but the first 12-hour brew I made was not nearly as strong as the original stuff I had from that cafe, so the next batch I increased the "brewing" time. I eventually settled on a minimum of 36 hours. The cafe owner that converted me claims that more than 24 hours will create a bitter taste, but that has not been my experience. I think that dynamic is determined by how coarsely the beans are ground. I hand grind my beans in a very unscientific manner so my exact method may not be reproducible.
The water is not hot to begin with. In fact, the brewing process can take place in the refrigerator, but I start with cool water and leave it out on the counter, not refrigerating until after I remove the coffee grounds.
My headache yesterday was from a sleep deficit. But you are right about watching out for the strength of the coffee. I usually dole it out in very small doses, which is why I can say for certain that I had 2 ounces yesterday. I never pour a whole bunch in a big glass as you would if you were serving iced tea. And it sometimes "hits" you as much as an hour after consumption, so it's easy to overdo it.
From left to right: a manual coffee grinder, an empty mason jar eager to start brewing, a conical strainer, and a batch of cold brew that will be ready this afternoon. In the foreground, a cold brew recipe book which I never use because almost all the recipes involve something sugary, and I just enjoy the taste of plain coffee.
Yes, I am well acquainted with that watery coffee every cafe and diner served us for decades. It was not only the brewing method that made that coffee so bad; it was a different kind of coffee. For some reason, after WWII, Americans stopped using Arabica beans and switched to some other lesser coffee bean. The coffee renaissance that we associate with Starbucks has involved a return to the Arabica bean. Yum!
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Dusty T., Northern California
Site Moderator
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie
updated by @dusty: 06/22/18 12:43:53PM