jaybar Senior Member Joined: 13 Sep 2011 Posts: 107 Location: Brooklyn Expertise: Just starting
Posted Sat Jun 30, 2012, 9:03am Subject: How much water do I need to brew 25 ounces of coffee?
Hi
I am unsure about how much water is needed to brew a given volume of coffee.
I would like to brew 25 ounces of coffee. I plan to use about 48-60 grams of coffee. Does that mean I start with 25 fluid ounces of water, or do I start with something approaching 28-30 fluid ounces of water, to allow for pre-infusion/absorbtion? I am very cunfused about this.
Posted Sat Jun 30, 2012, 4:37pm Subject: Re: How much water do I need to brew 25 ounces of coffee?
The starting point is normally recommended as 60g coffee to 1 ltr water, and work from there until you find a ratio you like for a particular coffee.
If you experiment and see how much is absorbed by the coffee bed, then allow for that by starting with a slightly higher volume water to get the resulting coffee volume you want, you can just up the amount of coffee slightly to maintain the same ratio.
Sorry, can't do fluid ounces these days, and then mixing metric with it as well gives me a headache ;o(
Posted Sat Jun 30, 2012, 5:01pm Subject: Re: How much water do I need to brew 25 ounces of coffee?
jaybar Said:
I would like to brew 25 ounces of coffee. I plan to use about 48-60 grams of coffee. Does that mean I start with 25 fluid ounces of water, or do I start with something approaching 28-30 fluid ounces of water, to allow for pre-infusion/absorbtion? I am very cunfused about this.
Coffee Produced = Brew Water - (Absorption * Dry Ground Coffee)
You need to have an idea for "absorption", but luckily we know that it's right around 2.0 for most pourover and drip methods.
You want 740g of coffee produced, your absorption can be assumed to be 2.
BUT you don't yet know how much dry coffee to use, or how much brew water to use. That's why it's important to have an understanding of "Brew Ratio".
Since you're using a pourover method (Chemex or Hario), a good starting point for normal coffee is about 17.4g of brew water per gram of coffee. The strength will be right about normal for normal extraction.
Let's just pick 17.4 as a brew ratio. If you do some quick algebraic manipulation, you can get the equation above to this:
Dry Ground Coffee = (Coffee Produced or desired) / (Brew Ratio - Absorption)
Since you set the brew ratio at 17.4, 48.7*17.4 = 847.4g of brew water is needed to get 740g of normal strength coffee into the pot.
Looking back, 847.4 - (48.7 * 2) = about 750g of coffee produced (pretty close, but we rounded off).
Hope that wasn't too bad.
If the coffee seems bitter or burnt, then adjust HOW you brew it but keep the same brew ratio (because you might be overextracting). If it seems weak, then try increasing the brew temperature, or slightly finer grind, but again, try and keep the same brew ratio.
So, there's your target parameters:
~850g of brew water ~48.7g of coffee
Should produce around 740-750g of coffee.
Good Luck!
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Posted Sun Jul 1, 2012, 5:52pm Subject: Re: How much water do I need to brew 25 ounces of coffee?
Incidentally, this is fresh in my head because I just did this - except I was making 700g of coffee, so it just worked for me yesterday... ;^D
45.5g coffee, 791g brew water, got 695g of coffee.
Strength was spot on target at 1.24% with a Colombia Estates that I roasted myself.
I was targeting a slightly lower than 20% extraction, but that's how it worked in practice for me.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
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