When cold-brewing coffee (such as a Toddy) at room temperature, what is the best steep time. Would a 1 or 2-hour steep time yield a decent cup of coffee?
Does anyone have any research on caffeine extraction efficiency in water at room temperature?
I've been using a Toddy for about two years now. I have found that you can get a plenty strong concentrate with only 1/2 pound of freshly ground coffee steeped in filtered water (like in a Brita) for just short of 18 hours. Beyond 18 hours the grounds become waterlogged and the same elements that produce the bitterness found in hot brewed coffee start to come out. 12 hours, though, is barely enough to get the flavor out. At only one or two hours, I can't imagine that there would be much flavor at all. If you use a Toddy, you will find that using a finer ground will result a very cumbersome, frustrating draining process and/or sediment in your concentrate. As to the caffeine, I believe you will find that the matter is undecided. Someone needs to conduct an experiment with well defined parameters to really figure it out.
Not research, but here's my personal experience.
I cold brew my coffee with just normal mason jars (not Toddy), the general suggested steep time is 12 hours. You can increase it to up to 24 hours depending on the strength you like your cup of coffee.
1 or 2 hours would be too short to extract the full body of flavors in my opinion if you were using the indicated coarse grind for cold brews.
I personally have tried experimenting with a finer grind (more like pour over grind) and leaving it for a shorter time, 2-3 hours or so. I felt that also produced a nice cup as the finer grind sped up the rate of extraction with the increased surface area. But even from my rather inexperienced palate, I could taste that the longer wait time is worth it after all! It just tastes smoother and a cleaner cup. Guess I need more patience for my cuppa.
And I think I read somewhere that cold brew gives about only 2/3 caffeine compared to the usual hot water brews.