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Topic: Cooling... (16 msgs / 409 lines)
1) From: Sean Cary
Yeah, I know we have beat this dead horse on a number of occasions - but I
am not sure I have seen this particular question asked.
Is the purpose of cooling to STOP the roast - or to rapidly bring them to a
lower temperature.
I was thinking tonight, after roasting some Brazil Yellow Bourbon that the
purpose was to end the roast, not so much the goal of getting them to room
temp or whatever.
I have not had a really good roast since returning from Iraq...seem to have
lost the touch.
Sean
-- 
Sean M. Cary
Major USMC
Tempus Fugit, Memento Mori
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2) From: Dave
On Mon, Apr 21, 2008 at 6:30 PM, Sean Cary  wrote:
<Snip>
I've always thought about it as stopping the roast. I really don't
understand what you might think the difference is.
-- 
Dave
Some days...
It's just not worth chewing through the leather straps
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3) From: Sean Cary
Is the purpose to stop the roast - or get them to a lower temp...what is the
ultimate goal?
I know this seems really simple, but I am thinking the two are distinctly
different...you can cool enough to stop the roast, but then you have to go
an extra amount to cool to X temp...
Maybe I am just over thinking this.
Sean
On Mon, Apr 21, 2008 at 9:57 PM, Dave  wrote:
<Snip>
-- 
Sean M. Cary
Major USMC
Tempus Fugit, Memento Mori
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4) From: Terry Stockdale
At 08:30 PM 4/21/2008, you wrote:
<Snip>
And, the answer is "Yes."
You need to stop the roast -- when the roast has gotten to second 
crack, it has changed from an endothermic process (you have to add 
energy/heat to continue the process) into an exothermic process (it 
gives off energy).  You need to cool it a little bit to shift back to 
endothermic.
Then, you need to continue cooling to prevent a degradation of the 
flavor.  Think "baking" the coffee.  You want to cool the coffee 
fairly quickly -- across 4-5 minutes -- to room temperature.  I wish 
I could find the reference, but I haven't been able to -- someone 
posted several years ago here or in alt.coffee with plot of cooling 
time versus coffee brightness.  The sweet spot was in the 4-5 minute 
cooling range.  Faster or slower resulted in a less desirable 
taste.  Obviously, this was subjective testing, but interesting none the less.
I used to have a Zach & Dani's roaster.  It's number one problem, as 
far as I was concerned, was that the cooling cycle was as long as the 
roasting cycle.  The result was flat and a terrible waste of SM green beans.
--
Terry Stockdale -- Baton Rouge, LA
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5) From: raymanowen
" Is the purpose of cooling to STOP the roast - or to rapidly bring them to
a lower temperature."
Let me enumerate my coffee Novice status- coffee roasting is a chemical
reaction.
Most chemical reactions progress more rapidly at elevated temperatures. To
terminate a reaction in progress, take the heat away, don't just let it cool
on its own. This is especially true when the reaction has become exothermic
and is making its own heat.
I have fun when I use my cooling device. It doesn't cool and remove chaff.
After it removes heat, I have all the time in the world to get rid of the
chaff- the roast is stopped.
Cheers, Mabuhay -RayO, aka Opa!
Got Grinder?
On Mon, Apr 21, 2008 at 7:30 PM, Sean Cary  wrote:
<Snip>
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6) From: wncopeland
Hi all,
    I'm another Bill, mostly enjoying reading the threads and I have learned a lot that has helped me as a newbie to roasting.  The purpose of cooling is to stop the roast.  Until the roast bean temperature is close to room temperature, or cooler if you are in a hot climate, the roasting continues at some level.  Right?  If you have reached the desired second crack for your roast, for example,  you don't want it to continue beyond that, so you would want to cool the roast quickly.    An exothermic reaction only begins when the beans  actually start to burn, like the charcoal in a barbecue.  SM calls this stage "imminent fire", stage 16.  I could be completely wrong, but my understanding would be that if you take the heat away prior to stage 16, cooling will begin.  Love to hear thoughts.  Bill C.
---------

7) From: wncopeland
Hi all,
    I'm another Bill, mostly enjoying reading the threads and I have learned a lot that has helped me as a newbie to roasting.  The purpose of cooling is to stop the roast.  Until the roast bean temperature is close to room temperature, or cooler if you are in a hot climate, the roasting continues at some level.  Right?  If you have reached the desired second crack for your roast, for example,  you don't want it to continue beyond that, so you would want to cool the roast quickly.    An exothermic reaction only begins when the beans  actually start to burn, like the charcoal in a barbecue.  SM calls this stage "imminent fire", stage 16.  I could be completely wrong, but my understanding would be that if you take the heat away prior to stage 16, cooling will begin.  Love to hear thoughts.  Bill C.
---------

8) From: Bill
Sean,
I actually appreciate you asking this question.  I've seen some arguments
about this around here, but as a peripheral.  I'd like to see some serious
discussion of this issue.  Times, as well.  RayO advocates dead stop and
(virtually) immediate cool, I think he's like 30 seconds to room temp.  But
I remember someone else, maybe John Despres, arguing that certain complexity
is lost if the beans cool too quickly...
So I'd like to see some discussion of this question.
Maybe Tom and MiKe want to chime in on the time it takes to cool a
multi-pound roast in a commercial roaster.  Or maybe the couple of fellas
who have 1 pound professional roasters want to let us know...
And I'd be interested to know if cooling is even something that the
roaster-builders seriously think about...
So thanks for a good question.  I'm hoping to be enlightened.
bill
Oh, and I know this is like the 3rd time I've said it today, but maybe you
should check out the HG method instead of the SC/TO that you've
got.................
On Mon, Apr 21, 2008 at 7:30 PM, Sean Cary  wrote:
<Snip>
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9) From: John Despres
Part 1, I cool to stop the roast by dropping below first or second crack =
range, part 2 I continue cooling to handle the beans.
Some beans cool in the drum for about two minutes, others dump straight =
to the colander/vacuum for a speed cooling.
For a while, I was experimenting and playing with drum cooling to 250F =
in the drum. I had a devil of a time figuring out the coast to the end, =
so I'm back to immediate stop the roast cooling in the col/vac. I did =
like the coast to cool because it evened out the roast and helped with =
chaff but I've sort of figured out how to even out the batch and the =
chaff I can handle with a wooden spoon in the col/vac.
That's about all I have to say about cooling... Is it what you remember, =
Bill?
Cool Beans!
John
Bill wrote:
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-- =
John A C Despres
Hug your kids
616.437.9182
Scene It All Productions 
JDs Coffee Provoked Ramblings =
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10) From: Ken Mary
For my own roast-brew-taste preference, I found that there is an optimum 
range of cooling profiles. Others who roast into second crack may find
problems quenching the roast fast enough, or have equipment not capable of
controlled cooling.
The easiest method is to aim for a temperature of 300F between 2 and 3
minutes after the start of cooling in the roaster. After reaching 300F, dump
the beans for final cooling.
In a popper, this means continued heating at a lower power. You can even
tailor the cooling profile if you want. Measure the bean temp by IR since
thermocouples will not read the bean temperature accurately. I used a simple
two stage cooling in my poppers, moderate heat to 300F, low heat to 160F,
then dump on a tray.
In my small toaster oven drum roaster, radiative cooling works ok. I can
open the door and remove the top from the oven while the drum continues to
turn at zero heat input. In my most recent roast, the finish bean
temperature was 218C (424F). After 3 minutes, the bean temperature was 160C
(320F). The beans are dumped on a tray for cooling to ambient.
At optimum cooling, I expect a large increase in complexity and what I call
"spice" for lack of a better description. But this latest roast was the
first controlled cooling in more than a year, and the first on this
particular coffee. What was unexpected was a huge increase in body (almost
syrupy) and darkness of the brew liquid. Now this result makes me want to
continue this on every roast.
--
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11) From: Ed Needham
I do 5 pound batches and my cooling device will take the beans to cold in 
about 3 minutes.  I think it's speculation that cooling too fast leads to 
loss of complexity.  I have never experienced this in over 30 years of 
roasting.
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************

12) From: Ed Needham
Your cooling profile seems to allow the beans to continue roasting without 
burning them.  I turn off the propane when I hear second begin, and wait 
maybe 15 seconds before dumping and quick cooling.
I do the same thing with a pop tart in the toaster.  I leave it in the hot 
toaster for a few minutes after it has already turned off.  The result is 
nicely toasted but not burned.  (OK, so sue me, I like brown sugar cinnamon 
pop tarts and coffee)
*********************
Ed Needham
"to absurdity and beyond!"http://www.homeroaster.com*********************

13) From: Bill Laine
Does anyone know at what temperature the beans actually stop "cooking"? My
Gene Cafe calls the cooling done at 140. Are they still technically cook=
ing
at this temp?
Bill
New Orleans
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14) From: Dennis & Marjorie True
I over came this in the Z&D by just pulling the roast as soon as the 
cooling started and brought the temps down faster myself...
I would then let the roaster cool down on it's own through the rest of 
the cooling cycle w/o beans in it.
Dennis
Terry Stockdale wrote:
<Snip>
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15) From: Ken Mary
From: "Ed Needham"
"Your cooling profile seems to allow the beans to continue roasting without
burning them.  I turn off the propane when I hear second begin, and wait
maybe 15 seconds before dumping and quick cooling."
My finish temperatures are always less than full city and safely short of
the exothermic region of second crack. When you are in the exotherm, you
must be decisive about quenching. But below that there is time for continued
roasting to improve the flavor when done properly. I have never gone into
second then returned to a lower temperature for continued roasting or
controlled cooling. I may try a few roasts, who knows, maybe I will discover
something new.
--
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16) From: Ken Mary
From: "Bill Laine"
"Does anyone know at what temperature the beans actually stop "cooking"? My
Gene Cafe calls the cooling done at 140. Are they still technically cook=
ing
at this temp?"
At any temperature above absolute zero, chemical reactions are always taking
place. But the rate of reaction may be slow enough to assume that nothing
significant happens over some time frame.
Roast reactions should begin near 250F and higher. We may safely assume that
no roasting reactions happen below 140F, but there are other "staling"
reactions and physical reactions like evaporation of volatiles that are
enhanced by temperatures near 140F and above. These staling reactions happen
even at room temperature, but the time frame is measured in days instead of
minutes.
-- =
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