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Topic: offgassing (15 msgs / 327 lines)
1) From: Phil Palmintere
I've been using the zip-lock bags from SM that have a 1-way valve to store
my roasted coffee (hot air popcorn popper).  Here's what I notice (still a
newbie, of course):  
* I roast about 90 to 100g of green beans (which seem to lose about 10g of
moisture & chaff), usually about 15 to 30 seconds in to 2nd crack.
* put the roasted cool beans in the zip bag with 1-way valve
* seal the bag
* and then "express" all air through the one-way valve.
Because I'm roasting only about 100g, the result doesn't fill the zip bag
more than about 1/2 full (if that).  So, any gas that is off-gassed should
puff out the zip bag quite a bit and ultimately the internal pressure should
be enough to open the 1-way valve a bit to allow some out.
I would think that after a few days of offgassing there should be a
noticeable amount of gas inside the zip bag.  But rarely do I get that -
instead it seems little if any gas has "offgassed" (is that a word?).  The
zip bag hasn't puffed.  My attempts to express any remedial gas through the
1-way valve yield essentially nada.
I don't think the zip bag or its valve are defective or broken.
Does this indicate I'm doing something wrong in the roasting process or
cooling process? (I use a metal sieve & a strong fan to cool the beans).
Thanks... phil
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2) From: Joseph Robertson
My experience has been that if you bag with in 15 minutes or less you should
be in the window to trap the Off gassing process.
JoeR
On Wed, Sep 2, 2009 at 8:02 AM, Phil Palmintere 

3) From: Greg Hollrigel
Good question Phil.  I have recently been wondering the same thing and was
considering asking the exact same question.  Of interest, is when I bought
some roasted beans from Klatch not too long ago, those beans filled the
vacuum bags for days (to the extent where the ziplock didn't hold).
I would appreciate the groups collective input on this topic as well!
Thanks,
Greg
On Wed, Sep 2, 2009 at 8:02 AM, Phil Palmintere 

4) From: Frank Cascarano
I believe the correct term is "outgassing."
I see the same thing.  The one-way valve bags never puffed up for me
either.  Then one day I vacuum sealed some beans instead of using the
valve bags.  Boy did they puff up.  Like little balloons.  I guess
there is gas coming off those beans.
-Frank
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5) From: Bob Hazen
Offgassing....   Outgassing....  Both mean the same thing to me.  This 
effect, or rather the lack of it, is what got me into homeroasting.
Back in the day, I bought my beans at one of the 1st gen Starbucks (or Wet 
Whisker which is another story).  This was back when Starbucks was on the 
cutting edge of Seattle's coffee scene - not anywhere near the behemoth of 
today.  Their beans were kept in bins in the store, not pre-bagged with 
one-year-out expiration dates.  What I found interesting was that putting 
the beans into a sealed glass jar upon arriving at home resulted in 
outgassing when opened sometime later.  The ensuing aroma was intoxicating. 
And the coffee was good.
Yes, dear reader, these were from our friend *$.
Sometime later - exactly when is unclear - I realized that my beans didn't 
go "pfffft" anymore.  Having already noticed that the "pfffft" declined as 
beans aged, I correctly deduced that I was being sold stale beans.  That 
epiphany resulted in homeroasting for me.
My beans have been going  "pfffft" ever since.
Oh yes, I admit to having bought another bag or two of "that other stuff" 
over the years.  Not so much a fit of masochism, but more desperation when 
both of my roasters were down.  The good thing about those little exercises, 
though, is that I was brutally reminded how good we have it >our way<
Bob
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6) From: Joseph Robertson
Co2
JoeR
On Wed, Sep 2, 2009 at 3:11 PM, Frank Cascarano  wrote:
<Snip>
-- 
Ambassador for Specialty Coffee and palate reform.
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7) From: Yakster
What is it they say on airlines?  Something like even though the bag doesn't
inflate, there is oxygen flowing to the mask.
I use canning jars and leave the lid loose the first night.  When I crank it
down the next morning after my morning cup, I'll hear the pfft the next day.
-Chris
On Wed, Sep 2, 2009 at 3:11 PM, Frank Cascarano  wrote:
<Snip>
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8) From: raymanowen
"I don't think the zip bag or its valve are defective or broken."
They're not busted, they just don't work, at best. On the patent drawing,
the reference note is: "One Way Valve." No legitimate testing of the "valve"
was done or reviewed. There are one way valves in some spin-on oil filters
and nearly every automatic transmission. They work well, and are never
constructed of paper or thin flexible plastic that wouldn't work.
"Does this indicate I'm doing something wrong?"
Not at all. The gas evolved is your friend, the fire extinguisher Carbon
Dioxide (CO2), and the rate of evolution is very slow. Depending on the
specific bean and roast, this out gassing continues for a week or more as
flavors develop.
The CO2 gas is more dense than Oxygen gas, (O2) which molecules tend to
"float" on top of the heavy CO2 layer.
No seal is perfect, so the marketing gimmick of the one-way valves in the
side of any bag are a ludicrous waste of people's money. Since the valves
are not good one-way seals and the zip lock seals or folded paper bags also
don't seal, what are the chances that the bag will be shipped or stored with
the one-way valve, the fold and/or the zip seal at the bottom?
The bottom orientation will force the expulsion of CO2 as any gas is
evolved, and it will never return. A radiator leaks, the water never goes
back in through the leak. Dump CO2, Oxygen comes back in, one-way valves be
Damned.
Cheers, Mabuhay -RayO, aka Opa!
-- 
Persist in old ways; expect something different - suborn Insanity...
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9) From: Mike Koenig
I'm gonna go on my p-chem tirade again and state firmly that gases DO NOT
behave like liquids do.  You will never get the "oil and water" effect with
CO2 and oxygen.  Yes, you will reduce the partial pressure of oxygen in the
container slightly, but you will never reduce it to anything approaching
zero.
Don't make me start explaining p-chem theory,  nobody wants to hear that
(not even most of us chemists)
Drink your roasted coffee within a week or two, and don't worry about the
minimal amount of staling due to oxygen in that time.  If you are a
mega-roaster that puts a 2 year shelf life on your coffee you need to worry
about the gaseous contents of your bags, as a homeroaster, you have the
luxury of not worrying about such things.  If your coffee is going stale in
the bags, you are either roasting too much, or not drinking enough.
--mike
<Snip>
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10) From: David liguori
Mike Koenig wrote:
<Snip>
Otherwise all the CO2 in the atmosphere would settle to the bottom and 
suffocate us.  Or if that didn't kill us, it would only take one pass 
through the centrifuges for every two-bit dictator to separate U235 from 
U238.
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11) From: Larry Williams
I store my beans in a canning jar with a snap lid and seal.  After roasting
I usually leave the jar unsealed over night and close it the next day.  On
my batch roasted this morning I stretched clear wrap over the opening,
secured it with a rubber band, and poked small holes with a needle, then
inverted the jar for storage.  I'm hoping the little CO2 thingies will
easily exist through the holes and improve the quality of the roast.  Maybe
I should patent this brilliant idea.
Larry
-- 
Larry Williams
Everyday Is a Saturday
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12) From: Floyd Lozano
it wouldn't because all the plants eat it up and spit out oxygen, and
there's more of them than there are of us ;)  at least, there used to be!
On Thu, Sep 3, 2009 at 10:45 PM, David liguori  wrote:
<Snip>
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13) From: raymanowen
I could keep quiet.
I should keep quiet and allow this dummheit to dissipate like flatulence.
You know better than that.
Aren''t you glad the flatulence does dissipate?
When a California house burns up or burns down, why doesn't the massive
volume of CO2 generated just sit there and smother the flames, or the volume
of smoke permanently obscure the visibility? Why have I been smelling
California and Utah here in Colorado?
Amusing, isn't it? Do you imagine the high and low pressure fronts on a
weather map are just some Coloring Book Fantastique, the unfinished 4th
movement of an unfinished symphony by Berlioz? I guess it's further along in
the book published by the people that sprinkle little seeds along a certain
street.
CO2 is so highly water soluble that the immense atmospheric and surface
water of the planet would immediately tie up the molecules. An Oxygen Cycle
converts the remainders to Oxygen by photosynthesis in the green plant life
down where we reside, at the surface.
Isn't it fulfilling to realize some useful idiots are clear-cutting and
burning rain forests, potential coffee-growing areas, in the name of
hardwood and land development profits?
Cheers, Mabuhay -RayO, aka Opa!
Go, Go, GO! See Jane Go!    (Keep reading- it gets into counting and even
more technical.)
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14) From: Mike Koenig
In an overly simplified explanation - the fact that the CO2 of a house fire
doesn't self-extinguish the fire is a similar effect to why you can't get
all the oxygen out of your bean jar by leaving the lid loose.  Gases will
always tend to mix, no matter how hard you try to avoid it.  (there's also
convection going on in the house fire example, which adds extra mixing to
the situation).
--mike
<Snip>
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15) From: raymanowen
"...why you can't get all the oxygen out of your bean jar by leaving the lid
loose.
Gases will always tend to mix, no matter how hard you try to avoid it.  "
Isn't a little mixing with a few rogue Oxygen molecules a better situation
than evacuating the jar for storage, then exchanging the interstitial
evolved CO2 molecules with a fresh batch of 20% O2 of the atmosphere every
time the vacuum is disturbed? -ro
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