HomeRoast Digest


Topic: I'd Like to Start an Argument about CO2 (11 msgs / 287 lines)
1) From: John M. Howison
Over the past year or so, reading this list and sampling a range of SM's
green bean offerings has vastly improved the quality of my roasts and thus
my coffee-drinking life.  The Zen of hand grinding has added a touch.
BUT, in one area of conventional wisdom, the List has not been confusing, to
say the least.  Absolutely everybody agrees that air is bad for roasted
coffee, ground or not, and nearly everybody seems to think that CO2 is even
more evil -- so evil that after roasting one should arrange for air to
displace CO2 ASAP.  To me, this makes no sense at all.
Just what effect is C02 supposed to perpetrate?
Presumably the overwhelming reason for protecting roasted coffee from the
air is that it disperses flavor, rapidly wasting the virtues of the bean.
I hear little discussion about what chemical effect oxygen, the potentially
active component in air, may have on our precious coffee.   This mysterious
effect must be present, as nearly all of us believe coffee is better after a
post-roast rest, mostly in sealed containers, of four hours to ten days or
so.  (My princely Abyssinian friend is the only dissident of my
acquaintance; he sticks to his ancestral brew-it-still-warm procedure and
arrives at a variant nirvana, a superb but different esthetic.)
My perverse reaction has been to believe that CO2 is actually a friend to
the extent that it impedes the evil effects of oxygen.   My procedure, which
I beg readers to attack, is as follows.  Immediately on completion of the
roast, without waiting for any in-the-roaster cooling procedure, I dump the
still hot beans into a stainless steel container and seal.  (I don't own a
light-proof ceramic or glass alternative.)  Supposing that rapid cooling to
avoid "baking" is in fact desirable , I immerse the container in icek)  Then
I store the container at room temperature for the recommended rest period of
the instant bean.
Ready to brew, I remove the needed dose of beans (for my Yama, FP, AP or
Mukkapot) as deftly as possible, allowing minimal time for the
briefly-opened container to replace CO2 with air, then grind and brew.  I
think the result is superior.
Possibly, even probably, the reason I like this procedure is not that it is
better, but that my taste sensors are deficient.   Okay, persuade me.
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2) From: Mike Koenig
John,
CO2 isn't evil (at least in terms of coffee),  it's just one
by-product of the reactions that go on during roasting.  The main
reason that you see people talking about not putting the coffee in a
sealed container is that this gas is trapped within the structure of
the bean,  and needs to escape.  If it's kept in a sealed container,
pressure will build up, and the gas trapped in the bean will maintain
a equilibrium with the pressure in the container (which is higher than
the atmospheric pressure), thus a certain amount will stay trapped in
the bean structure.
--mike
On Thu, Dec 11, 2008 at 10:17 AM, John M. Howison
 wrote:
<Snip>
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3) From: jon morgan
co2 is good. When I send coffee to friends or family I flush the bags with
co2 to make sure there is no oxygen in there.
On Thu, Dec 11, 2008 at 11:04 AM, Mike Koenig  wrote:
<Snip>
-- 
Jon Morgan
Fire Protection Associates, Inc.
706-215-1094
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4) From: Carol Lugg
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5) From: Michael Vanecek
The problem with storing still warm coffee in a sealed environment is 
condensation - water is even more evil than oxygen to the degradation 
and staling of coffee. It's been recommended that coffee be allowed to 
cool first then be stored. I've never seen anyone say CO2 was bad for 
coffee - oxygen is the gas to limit as much as possible.
Be well,
Mike
-- 
Zone 8, Texashttp://www.taroandti.com/Exotic Plant Info and More...
John M. Howison wrote:
<Snip>
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6) From: Michael Vanecek
A happy medium between leaving the beans out - which exposes them to 
more oxygen and atmospheric moisture, and sealing them up, which 
potentially increases intra-spacial pressures that could reduce the rate 
of out-gassing is a button-bag - which expands with outgassing, can be 
purged by squeezing, and allows no oxygen back in. I've been using those 
for years and my coffee has yet to prematurely go stale. Tho, the coffee 
doesn't stick around very long either... :-)
Be well,
Mike
-- 
Zone 8, Texashttp://theblessing.mjvm.org/Carol Lugg wrote:">http://www.taroandti.com/Exotic Plant Info and More...http://theblessing.mjvm.org/Carol Lugg wrote:
<Snip>
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7) From: Les
John said, " Immediately on completion of the
roast, without waiting for any in-the-roaster cooling procedure, I dump the
still hot beans into a stainless steel container and seal.  (I don't own a
light-proof ceramic or glass alternative.)  Supposing that rapid cooling to
avoid "baking" is in fact desirable , I immerse the container in icek)  Then
I store the container at room temperature for the recommended rest period of
the instant bean."
First off you want to cool your beans to ambient temperature before
storing your beans.  You want your beans to degas.  My experience has
been that the beans will degas just fine in a closed container if you
don't totally fill the container to the top.  I leave space at the
top.  I usually store my coffee in Tupperware containers, or oneway
valve containers.  I have also found that CO2 is heavier than O2, so
the best thing to do is scoop you beans from the container.  I have no
way of testing that the CO2 continues to cover the beans, but I have
maintained quality fresh beans for 18 days using this method.  One of
the easiest ways to ruin a roast is by not cooling before storing.  I
would not use your method.  I would cool them before putting them in
your stainless container for storage.
Les
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8) From: Tom & Maria - Sweet Maria's Coffee
<Snip>
Agreed - cooling is critical. Since none of us (presumably) measure 
o2 and co2 in our coffee, we just use our anecdotal observations over 
time. I know when an espresso hasn't degassed enough ... you can 
taste it for sure, and there are extraction issues. Stale coffee is 
another matter, and not something much of us have problems with, 
since that is the main problem with commercial coffee that home 
roasting solves. So maybe, in lieu of that, we focus on degassing a 
bit much, which is nearly NEVER a problem a customer of roasted 
coffees faces. Even at a good roasting shop, bins of bulk coffee are 
going to be 3-5 days old. What I used to do is make a pinhole in the 
lid of a mason jar, and allow for co2 to push out oxygen naturally. 
That coffee was never around long enough to face the problem of 
oxdidation. Anyway, it's a good discussion ...
Tom
--
                   "Great coffee comes from tiny roasters"
            Sweet Maria's Home Coffee Roasting  -  Tom & Maria
                      http://www.sweetmarias.com                Thompson Owen george_at_sweetmarias.com
     Sweet Maria's Coffee - 1115 21st Street, Oakland, CA 94607 - USA
             phone/fax: 888 876 5917 - tom_at_sweetmarias.com
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9) From: Clay Spence
On Thu, Dec 11, 2008 at 5:09 PM, Tom & Maria - Sweet Maria's Coffee <
sweetmarias> wrote:
<Snip>
Slightly off-topic: CO2 is heavier than the oxygen and nitrogen in air, so
there is a tendency for it to sink. I suspect it's just a tendency, any
little draft causes at least some mixing. Now, I think the new coffee tins
are really cool, but because I think the CO2 likes to sink and the valve is
on the bottom of the tin, I store these upside down, so the out-gassing CO2
sinks to the bottom (hopefully) and forces the other stuff out the valve on
the top. After 12 hours or a day it's probably not out-gassing anymore, so
it doesn't matter. (I have my compulsive side.)
Clay
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10) From: R Nepsund
I'm wondering if the CO2 from the beans is binding the carbon to it's oxygen
during the roast or after.
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11) From: raymanowen
" ...[CO2] gas is trapped within the structure of the bean,  and needs to
escape. [Why?]
If it's kept in a sealed container, pressure will build up, and the gas
trapped in the bean will maintain a equilibrium with the pressure in the
container (which is higher than the atmospheric pressure)
If it's kept in a sealed container, pressure will build up, and the gas
trapped in the bean will [be the same as] the pressure in the container
(which is higher than the atmospheric pressure), thus a certain amount will
stay trapped inthe bean structure."
[The density of CO2 molecules is greater than O2 molecules, pressure macht
nichts.]
Whenever oxygen and carbon dioxide are present in the same volume, the O2
will always be upstairs. If the volume has a leak at the top, the CO2
evolved by the fresh roasted coffee beans will displace O2 and fill the
space from the bottom up, just like water fills a glass or Mason jar.
Cheers, Mabuhay -RayO, aka Opa!
On Thu, Dec 11, 2008 at 9:04 AM, Mike Koenig  wrote:
<Snip>
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita (ex- NYC Paramount) WurliTzer- 1976
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