HairVise Senior Member Joined: 11 Dec 2013 Posts: 1 Location: San Francisco Expertise: I love coffee
Posted Wed Dec 11, 2013, 11:28am Subject: Aeropress Java Jug
I recently bought a Java Jug from Aeropress so that I could use my press while traveling as well as to make two cups of coffee at a time. For a single cup, I use the inverted method with 16 grams of coffee, brewing for a minute, and I'm very pleased with the results.
Trying to make enough coffee for two has never worked for me though. If I double the amount of coffee, then the concentrate is very small. Adding enough water to the second cup line on the jug makes for a very watery and disappointing coffee.
Anyone out there have any brilliant techniques for making more than one cup at a time with the aeropress and java jug?
jpender Senior Member Joined: 11 Jul 2011 Posts: 614 Location: California Expertise: I like coffee
Grinder: OE LIDO Vac Pot: S/S Moka Pot Drip: Aeropress
Posted Wed Dec 11, 2013, 4:22pm Subject: Re: Aeropress Java Jug
I haven't done this, but two ideas come to mind. The first is to brew in a larger container and only use the Aeropress (in stages) or a cone filter to seperate the coffee from the grounds. Then you don't have to worry about making a concentrate.
If you insist on using the limited confines of an Aeropress in a single stage then you'll have to updose to compensate for the loss of dissolved solids in the grounds. All else being equal, this is a formula for figuring out how much coffee you'll need:
c = (e - sqrt(e^2 - 4easm/w)) / (2ea/w)
c = amount of coffee e = extraction (e.g., 0.20) a = approximate absorption ratio of grounds (e.g., 1.2) s = strength of coffee in mug (e.g. 0.0125) m = size of mug w = brew water that will fit in the Aeropress
This will produce a concentrate of volume: x = w - ac, at a strength of ec/(ec + w). So you'd need to add (m-x) hot water to the concentrate to get your mug.
He's using 16 g of coffee to make "one cup" so assuming his coffee is about 1.25% strength that means his cup is around 8 oz, i.e. 1 cup. So in order to make twice this much he'll have to use 2 cups of water plus the amount of water that the coffee absorbs. That's going to something like 500 ml. The Aeropress when inverted with the plunger inserted only 1 cm has a volume of about 290 ml. Not even close! Even my modified Aeropress can only hold about 320 ml.
If you plug the numbers into the equation I wrote above (with 20% extraction, 1.25% strength, 1.2 absorption factor, a 460 ml mug, and with the expectation of fitting 220 ml of water into the inverted Aeropress, you will find that you need 36 g of coffee. That's considerably more than twice his 16 g dose because so much of the strong (~3.3%) coffee is trapped in the grounds. The resultant concentrate would be only ~175 ml while over 40 ml of coffee the same strength would be stuck in the grounds. Almost one fifth of the coffee is lost. This is why it's so inefficient to do it this way.
I think a larger Aeropress would have a market. Maybe not a big enough market for Aerobie though.
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