HomeRoast Digest


Topic: Variables when resting beans (10 msgs / 324 lines)
1) From: David Morgenlender
I've read a lot of discussion regarding the length of time to rest beans.=
  But I
haven't come across anything regarding variables besides time & beans =
(type of
bean, roast level).  For me, other variables include method of storage =
(valve
bag vs. mason jar with a vacuum seal via Foodsaver), and how often the =
bag or
jar is opened (& for how long).  
In particular I wonder the effect of opening & resealing the mason jar.
Presumably, the beans release gases faster into a vacuum than into air, =
until
partial pressures equalize (or something like that, since it's been a =
LONG time
since I've taken a physics class! :) ).  Then if air is let into the jar =
for a
short time, there is some kind of gas exchange in both directions;  if =
the jar
is quickly resealed, however, this exchange is minimal before a vacuum is
re-introduced, at which time the beans proceed to lose more gas.  So, in =
this
scenario total gas loss is much faster than if the beans are stored in =
air, or
in a vacuum which remains sealed.  The result would be a reduced rest =
time
(assuming the positive effect of rest is simply loss of CO2 or other =
gases), but
conceivably a reduced time until the beans become stale (depending if =
loss of
gas contributes to this).  
Does this make sense?  Has anybody considered these issues further?
Dave
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Dave Morgenlender
e-mail: dmorgen
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2) From: miKe mcKoffee
Yes, have pondered the imponderable. (Though based on numerous discussions
as well as taste comparisons over the years totally unconvinced roasts out
gas faster vacuum sealed as post presumed.) Bottom line found it's best to
just use brew 'em up in a week or two, differing roast storage methods
really have little impact that way! But yes I'll continue to be extreme and
vac jar my roasts:-)
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Kurmudgeon miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/
 
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3) From: Justin Marquez
On 4/18/07, miKe mcKoffee  wrote:
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MiKe - "Bottom Line" is:  what works for you, works for you.  Sic'em, Tiger!
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)

4) From: David Morgenlender
I didn't mean that roasts outgas faster in a vacuum.  They probably do, =
but only
to the point of equalizing partial pressure, so it's probably not a =
significant
factor.  But, the amount of gas lost from the bean is presumably greater =
into a
vacuum.  And, each time the jar is opened then resealed, the beans are =
exposed
to 0 partial pressure (or very close to it, since not a perfect vacuum, =
and
presumably there is some CO2).  So it outgases again after each reseal.  =
This
might result in greater total outgasing using a vacuum than a valve bag. =
 I
don't know if this is in fact true, but it's my theory!
Dave
On Wed, 18 Apr 2007 12:39:10 -0700, you wrote:
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discussions
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out
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to
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and
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must
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enlightenment
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before.
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unsvbscribes) go to =http://sweetmarias.com/maillistinfo.html#personalsettings==========================
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Dave Morgenlender
e-mail: dmorgen
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5) From: Tom Ulmer
My take is a bit different. Have you ever noticed the "bloom" that occurs
when you pour water over freshly roasted and ground coffee? It has been
years since I was exposed to organic chemistry, and quite honestly it was
during a time of heavy experimentation, but it seems quite vividly to me
that there is some sort of reaction going on there. This reaction diminishes
in magnitude as the coffee stales. I will postulate that freshly roasted
coffee must be in contact with elements that are common in air and water
(hydrogen and/or oxygen?) in order to "rest" properly. At some point the
coffee becomes "over-rested" and desirable flavors fade.
Someone posted their simple solution to a quick rest that I have found
suitable for my use and that was to grind the coffee and let it sit for some
period before brewing.

6) From: Justin Marquez
On 4/19/07, Tom Ulmer  wrote:
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Tom, I have always *assumed* that the bloom was CO2 evolving from the
grounds as the hot water infused and forced the CO2 out.  The CO2 may be
making an emulsion with the oils that are forced out as well giving us that
foamy look to the bloom.  CO2 is less soluble in hot water than in cold
water, so I would expect it to come right out of the hot water.
As time goes on, there is less bloom when you brew. I have always *assumed*
that means the CO2 has already outgassed from the beans before we grind them
with more time.  I have always referred to  "over-rested coffee" as  "stale
coffee".
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)

7) From: Tom Ulmer
It seems likely that carbon dioxide is a product of combustion. Is the
assumption that roasting is a partial combustion which continues to produce
carbon dioxide or that the carbon dioxide is somehow trapped in the roasted
bean? Or is it perhaps another process altogether that I am failing to see?

8) From: miKe mcKoffee
I've always understood CO2 out gassing comes from CO2 trapped within the
roasted beans cellular structure during the roast process being released.
Don't ever recall reading (online or books) anything about CO2 continuing to
be produced post roast, but have good not perfect recall so may be mistaken!
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/
<Snip>

9) From: Tom Ulmer
Might there a correlation between carbon dioxide out-gassing and proper rest
interval?
I typically leave the container lids open for the first 24-36 hours of rest
as I prefer the flavors developed this way to beans sealed in containers
soon after roasting.

10) From: Justin Marquez
From Sweet Maria's site:http://www.sweetmarias.com/roasting-VisualGuideV2.html-------------------------------------------------------------------------------------------
*Full City Roast, Full City+ Roast**
415-425 degrees f. internal bean temperature, 438-448 f by thermo-probe
This image represents a lighter Full City roast, where the coffee has just
barely showed signs of 2nd crack -a snap or two-, or that 2nd crack is
imminent, and the roast is stopped. The actual temperature that second crack
normally occurs is higher: 446 degrees f internal bean temperature. But in
fact second crack is a little less predictable than first crack, in my
experience. Why? It could be explained as this: first crack is the physical
expansion of the coffee seed as water and carbon dioxide split and CO-2
outgassing occurs. Second Crack is the physical fracturing of the cellular
matrix of the coffee. This matrix is wood, also called cellulose, and
consists of organized cellulose that reacts readily to heat, and
not-so-organized cellulose that does not. Since every coffee is physically
different in size and density due to the cultivar, origin, altitude, etc. it
might make sense that the particular cell matrix is different too, and not
as universally consistent in reactiveness as H-2O and CO-2.
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Somewhere else (didn't ferret it out...) it tells that the CO2 produced is a
result of the carmelization of sugars in the beans.
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 4/19/07, Tom Ulmer  wrote:
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