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Topic: Exothermic and envirnoment vs bean mass temps > (7 msgs / 132 lines)
1) From: miKe mcKoffee
Nope, coffee beans go exothermic long before the beans flame on. Here's one
graph that illustrates:http://homeroaster.com/exotherm.htmlDuring even early 2nd crack roast environment temp can be below bean mass
temp and bean mass temp will continue to rise. In fact I usually have
environment temp below bean mass temp going into 2nd so 2nd doesn't race
away, how much lower depends on how far into 2nd intending to go. Actually
usually start bringing environment temp down towards bean temp as 1st
approaching and environment temp drops below bean mass during 1st.
Which is why on roasters like the Gene and Behmor with in drum cooling
nailing final degree of roast (initially) more difficult. You must
compensate for the continued roasting while roast environment temp drops far
enough to actually begin cooling rather than slowed roasting.
If you take "all heat away" then yes you're cooling, but that is not the
case if simply turning the heat off. The heat must be removed from the
environment not just no longer applied. Or the environment changed, as in
quenching or beans exiting the roaster to be cooled. 
Pacific Northwest Gathering VIhttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mckona/PNWGVI.htmKona Konnaisseur miKe mcKoffeehttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately 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.
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 An exothermic reaction only 
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2) From: wncopeland
Mike,
    On that graph, the roaster was turned off at some 2 minutes beyond second crack.  I bet the beans were  becoming charcoal by then, and therefore exothermic.  I believe that there will be no exothermic activity at any roast time that you would normally use.    Bill C.
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3) From: wncopeland
Mike,
    On that graph, the roaster was turned off at some 2 minutes beyond second crack.  I bet the beans were  becoming charcoal by then, and therefore exothermic.  I believe that there will be no exothermic activity at any roast time that you would normally use.    Bill C.
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4) From: Jim Gundlach
Mike,
      You nailed it here.  This is one of the posts that needs to be  
added to the non-existent FAQ.
           pecan jim
On Apr 22, 2008, at 12:13 AM, miKe mcKoffee wrote:
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5) From: Mike Koenig
Once you provide enough thermal energy,  chemical reactions start
taking place ( a concept known as "activation energy").  The breaking
of chemical bonds typically results in the release of energy, as new
bonds in lower energy states are formed, hence the beans becoming
exothermic, which happens at both first and 2nd cracks.
Fire is just the most extreme of the exothermic reactions (carbon, co2
and water exist in much lower energy states than the complex molecules
of coffee, so once you provide enough thermal energy for this to
happen the results are spectacular ),  but there are lots of other,
less destructive reactions that happen that result in the release of
energy (don't know the details of what reactions occur, but
caramelization of sugars is one of them...  a food chemist I am
not...)
--mike
On Tue, Apr 22, 2008 at 1:26 AM,   wrote:
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6) From: wncopeland
Thanks Mike for your reply   Bill C
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7) From: wncopeland
A second thanks from me, Bill C.   Mike, I hope I can solve the double e-mail problem.  When I hit reply all, which I took to mean reply to the group, the message was sent twice.  I did not cc you.  My computer must just be extra garrulous.  It appears that the reply button sends one message to the whole group, instead of to the individual.  I have not done much computer talking.    Bill C
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