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Topic: high altitude brewing (13 msgs / 273 lines)
1) From: Les & Becky
Rick,
You may want to consider a pressure cooker to get your water temp higher!  I
have a friend who lives in Equador who uses a small pressure cooker to heat
his water so that it will be hot enough for brewing.  He says it is a little
like Halloween when he pour the bubbling water through his Chemex!  You also
have to be very careful to depressurize before taking the top off.  And when
the top is off, the water is a rolling boil even though it is less that 100
degrees C.  You can even get a pressure cooker for the microwave!
Les
P.S.  We are getting a little lax in changing the subject lines again please
change them!

2) From: EskWIRED
<Snip>
Somebody help me out - I didn't do well in High School chemistry.
I thought taht water could get no hotter than boiling point, which is
determined by atmospheric pressure.  So when the pressure is released,
wouldn't the water suddenly boil very fast, and be reduced to the boiling
point?  How would it stay at above-boiling long enough to pour and brew?
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3) From: James Gundlach
On Thursday, October 24, 2002, at 04:20 PM, EskWIRED wrote:
<Snip>
They did not have chemistry when and where I went to high school but my 
understanding based on experiences would tend to agree with you.  By 
the time you get the pressure down so you can open the pressure cooker 
without it blowing up in your face the temperature is back down to 
boiling at that altitude.  The Joy of Cooking provides the following 
information:
        Altitude	F	C
	0		212	100
	2k ft		208	98
	5k		203	95
	7.5k		198	95
	10k		194	90
	15k		185	85
	30k		158	70
If I remember right, the ideal extraction temperature is around 192 to 
195 F so 10k should be about the right place to brew.
Jim Gundlach
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4) From: Rick Farris
David wrote:
<Snip>
<Snip>
Exactly.  But it's no sense arguing with someone that doesn't have the
background to understand it.  Any solution requires that the water be under
pressure until it exits the coffee grounds.
I looked at a Moka pot today (I'd never opened one up before) and I don't
really see how it's going to help unless I pack the coffee chamber
completely full, so that the decompress until it leaves the puck.  I don't
know if that would be too many grounds, but if it is, I guess I could make
Americanos.  :-)
-- Rick
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5) From: EskWIRED
<Snip>
What if you extended the top tube on a moka pot, so that weight of the the
column of water made up for the lack of air pressure?  I would think that
the pressure would have to build up more in the base, thus raising the
boiling point.
(I'm better at physics than chemistry)
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6) From: Rick Farris
EskWIRED wrote:
<Snip>
So then ... let's see ... in order to add one atmosphere of pressure, how
tall would the column of water have to be?
-- Rick
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7) From: Andrew J. Lynn
Rick Farris wrote:
<Snip>
hmmm... 1 atmosphere is about 14 pouns/square inch = 6.35kg/in^2 = 
6.35kg/6.45cm^2 ~= 1 kg/cm^2, 1 kg is 1 liter of water is 1000cm^3 so to 
all 1 atmosphere you need 10 meters high of water.
I had a good friend in college who in a fraternity - the phrase that 
comes to mind is "four story beer bong."  Same concept - find an open 
stairway and install some tubing with an open container at the top.
Of course, you don't need to add a whole atmosphere, I'm not sure what 
you do need but you can probably get away with a couple meters.  So a 
floor-to-ceiling coffee maker would do it for you (and you'd get a whole 
lot of coffee geek cred for your web page on the design).
Make it out of pyrex, a ceiling height tube of the stuff, and at the 
bottom of the tube is a beaker.  The beaker has a bunsen burner under it 
and a pressure valve that lets off the steam at a certain pressure 
differential that you'd have to calculate.  You have a (I forget the 
word but it's a stopper at the bottom of the tube that passes liquid 
through when you turn a knob) to feed from the tube to the beaker, and 
another to feed from the beaker into chamber that holds the grinds 
(looks like a Chemex) and yet another to bleed off the finished coffee 
from the bottom of the Chemex.  The whole thing is pressurized.  For 
added style points the top of the long tube has a Brita filter mount. 
 At sea level it's an espresso maker.  Yes, it's all making sense to me, 
I can draw it up if you want to build one :)
Andy Lynn
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8) From: Irene and Lubos Palounek
EskWIRED wrote:
"What if you extended the top tube on a moka pot, so that weight of the
column of water made up for the lack of air pressure?"
Wouldn't it be easier to build a sealed box for your brewer and increase the
pressure in that box? That should work, for example, for an electric vacuum
brewer, correct?
Lubos
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9) From: dewardh
For espresso it would be soooo simple . . . you need only a little popoff valve 
at the outlet of the portafilter, set to whatever pressure/temperature you 
desire.  Some small amount of the "brew" would flash to steam as pressure 
reduced at the valve, so a splash guard might be in order, but that's hardly an 
insurmountable problem.  An espresso machine is already a completely sealed 
pressure system, from the pump inlet to the group head . . .
Deward
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10) From: EskWIRED
<Snip>
I don't know, but maybe I can look it up.  Wait a sec...............
OK.  1 atmosphere at sea level is equal to a water column 33.9 feet high,
which is the same as 29.92 inches of mercury.  At 5000 feet, the atmosphere
is equal to 24.89 inches of mercury, and at 10,000 feet, it is equal to
20.58 inches of mercury.
Somebody is going to have to confirm my math, but...
33.9x12 inches of water.
So 1 inch of mercury = 406.8/29.92=~13.6 inches of water.
So at 5000 feet, you need to add 29.92-24.89=5.03 inches of mercury, or
5.03x13.6h.41 inches of water.
Rounding off, a 5 1/2 foot extention onto a Mokka pot should make the water
boil just like it does at sea level.
A REAL CSA member would have no problem rigging this up  :)
HTH.
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11) From: Angelo
Isn't that the principle behind the "Crema enhancing" portafilters?... 
Maybe one of those might work...
A.
<Snip>
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12) From: Charlie Herlihy
 A couple of years ago I found myself, along with lots of sadly
supprised travelers, stuck at a road blocked pass at 7,500 feet
in the middle of winter in Oaxaca Mexico. It was freezing, and
windy. The villagers blockading the road weren't moving untill
the governor conceeded to their demands, but to be friendly to
the stranded and shivering motorists and bus passengers they
brewed up hundreds of gallons of strong coffee that was
incredebly delicious. Ten gallen drums full of fresh spring
water heated over wood fires till boiling, about a lb. of fresh
roasted high grown beans from just down the road, and a kilo or
so of cane sugar and a couple of cinemon sticks per drum was
added and the water brought back to almost a boil. Cover, let
sit a few minutes-god's own coffee, I swear. I must of drank 30
cups myself that long cold night. High altitude brewing...
Charlie
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13) From: Scott Jensen
What a grand adventure Charlie!!  And probably much nicer looking  back on!
:)  The coffee sounds wonderful, be fun to try next time I'm up in the
hills.
Scott


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