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Topic: (Fwd) Re: +So much for that theory (27 msgs / 687 lines)
1) From: Jim Schulman
On 13 Dec 2003 at 16:48, AlChemist John wrote:
<Snip>
I figured since you used mass spectrometers, you might be able 
to make heads or tails of Staub's article on roasting, http://www.sweetmarias.com/roast.carlstaub.htmlcited by Ed 
earlier in this thread.  
Jim

2) From: AlChemist John
Ah, sorry about that, I scanned Ed's post in that I only read the text, not 
who quoted it.
Anyway, per se, yes I can make heads or tails of it.  Something in 
particular you wish gleaned from it?  I especially like the BRR and MET 
section, but those are going to take a bit to digest.
"The best cup characteristic are produced when the ratio of the degradation 
of trigonelline to the derivation of Nicotinic Acid remains linear." is a 
great statement if it is true (which I have no reason not to believe on 
face value).  I want to think on it and see if there is anything inherent 
in the statement or article on how to use this information.
Sometime around 00:05 12/14/2003, Jim Schulman typed:
<Snip>
--
John Nanci 
AlChemist at large
Zen Roasting and Blending by Gestalthttp://www.dreamsandbones.net/blog/

3) From: Gene Smith
<Snip>
As one who has built spectrometers but not used them, I thought this might
be the moment to ask a simpler question.  There must be some ideal
temperature curve calculations out there somewhere, but I haven't stumbled
across them yet.  Having just mounted a thermometer from Sweet Marias in my
ancient Melitta Aromaroast, I have been running batches of throwaway beans
and plotting temperature rise against time, to establish a baseline against
which to measure progress.  But I need to know what I'm aiming for.
First results with beans just shy of "max" line in roaster:
1minute     270F
2minutes    330F
3minutes    355F
4minutes    365F
5minutes    375F
6minutes    377F
7minutes    380F
8minutes    380F
Clearly I need to get the temperature up at the end, but how does the rise
at the beginning look?
The other thing that surprised me is that I have read a number of the
details published about the Aromaroast, all of which seem to suggest that
slowing down the fan should make the roast hotter.  But when I move the
switch on mine to the slower fan postition, the temperature drops.
Actually, "plummets" would be a better description.  What's going on?  Have
I misunderstood what others have written about this machine?
Gene Smith
riding the wild learning curve in Houston

4) From: AlChemist John
That actually was what I was aiming for when I asked for roast curves of 
good and bad profile curves.  I think I am seeing a pattern but the sample 
set is pretty small. :-(  What I am seeing is a particular (surprising) 
shape to the first derivative of the curve when the original curve is 
greater than 1st order.  Anyone want to offer up some down right bad roast 
curves?
Sometime around 09:17 12/14/2003, Gene Smith typed:
<Snip>
--
John Nanci 
AlChemist at large
Zen Roasting and Blending by Gestalthttp://www.dreamsandbones.net/blog/

5) From: Gene Smith
AlChemist John writes:
<Snip>
Yes, please!  And if possible keep it simple enough that those of us who
recognize a curve when we see one, but are a little iffy on first
derivatives and whatnot can grasp it?
Gene Smith
riding the wild learning curve in Houston

6) From: Ed Needham
Gene...the adjustment on your Aromaroast is not a fan speed adjustment, but
rather an air baffle.  It slows or speeds the airflow.  When you lower the
airflow, the heater output remains the same, so the air is hotter.  If you
are experiencing a 'drop' in air temperature, then it may be because the
beans are not agitating and the hotter air is not getting out, thus, the temp
probe is reading cooler air while the bottom of the bean mass is burning.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

7) From: Ed Needham
How about 360F roaster temp at the start, 360F at the finish one hour later.
or 550F at the start and 550F at the end of second crack.
OK, these are extremes, but typically, anything nearing these extremes will
produce a bad roast.
Pulling the beans before first crack is finished will also produce a bad
roast.
Letting the roaster temperature drop below bean temperature during the roast
will produce a bad roast.
I could think of a bunch more, but most are variations of the above.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

8) From: Gene Smith
<Snip>
but
<Snip>
temp
<Snip>
Thanks, Ed.  I understand the air baffle thing now.  However, I mounted my
thermometer through the plastic part of the handle attached to the metal
chaff catcher, to space the tip of the probe just above the screen, and well
down in the coffee - at the bottom layer of beans, I'm pretty sure.  And
yet, when I have hit max. temp., if I throttle back on the air, the
temperature drops rapidly.  If it was making the air blast hotter, how could
this happen?
And it works the same way on the way up the temp. scale.  Starting from
cold, the higher airflow - more open baffle - increases temperature *much*
faster than the throttled back setting.  It also seems to be true whether
there are beans in the roasting chamber or not.
Gene Smith
riding the wild learning curve in Houston

9) From: Ken Mary
<Snip>
The underpowered Aromaroast does some odd things. To be clear, you should
know that the maximum airflow occurs with the lever close to the "on"
position, and at the word "roast" the airflow is minimum and temperature is
maximum. Trying to read bean temperature may be misleading. Position the end
of the thermometer about 1/2 inch below the top of the roast chamber. Here
you can read the more stable air temp above the beans and use it to base
your profiles. It is only a rough approximation of bean temp and is greatly
affected by airflow. An alternative is to poke a hole in the screen bottom
to insert the thermometer to read the inlet temp.
I gave up on temperature in the Aromaroast and used lever position and time
to profile. Lever position is governed initially by adequate bean movement.
I use maximum flow until the beans lose density, then some profiling can be
done until near the finish when the beans may start to blow out into the
trap. Keep lifting the trap to check on bean movement.
--

10) From: Ken Mary
<Snip>
Maybe yes, maybe no.    :-)
During a recent roast, I purposely ran the heater one minute on and one
minute off for 10 minutes at the start. The bean temps rose to about 340F
and fell to about 185F. Then full heat to the finish 431F in another 5
minutes. While not as good as conventional profiles, the result was still
very good, but a little flat. Maybe good beans can take some abuse.
There could be a critical part of the profile where falling temps are bad.
But in 99% of my roasting I try to keep the temp rising at all times. So I
do not have much experience with falling temps.
--

11) From: Jim Schulman
On 14 Dec 2003 at 6:43, AlChemist John wrote:
<Snip>
Thanks. If it translates into any practical advice (short of a 
mass spectrometered popper) it would be good to know.
Jim

12) From: Jim Schulman
On 14 Dec 2003 at 12:29, Gene Smith wrote:
<Snip>
Simple airroasters have the typical asymptotic curve of a body 
rising to the ambient temperature, fast at first, slowing down 
as it gets closer to ambient. This is beacasue they blow air at 
a constant temperature. Drum roast curves are much more straight 
line, since their mass acts as a thermal capacitor.
My experience is that a straightline, drum roast profile yields 
a wider "sweetspot" to the roast, so it's a lot easier to get a 
good roast from it at different timings and degrees of roast.
I'm beginning to suspect that we guys controlling our 
airroasters super precisely may be overdoing it, and that an 
airroaster that blew at temperature X (say 320F or so) or even a 
certain percentage of heat output for 3 to 4 minutes, then 
ramped up to temperature Y (say 490F) or full heat over 7 to 10 
minutes, then stayed there until the roast was done, would do 
just as well in terms of producing a full taste and wide 
sweetspot.
Jim

13) From: Ed Needham
Don't have a clue.  My Aromaroast would not even take the beans through the
cracks when it was on high air.  If you get hotter temps when the air is
faster, you might have a machine that can really roast beans.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

14) From: Ed Needham
I guess I need to clarify that a bit.  "According to Staub's theory..."
He says that if it drops and 'exotherms' during the caramelization phase, it
allows weird branching of polymer chains, and possibly off tastes.  Your
experience casts a bit of shadow on his assertion though.http://www.sweetmarias.com/roast.carlstaub.htmlOnce I understand his stuff, I guess I'll quit quoting him so much.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

15) From: Ed Needham
I hate to quote what somebody else said without a citation, but I remember
Barry Jarrett saying that he doesn't futz around with the temperature
roasting with his Diedrich most of the time.  Puts the beans in at a given
temperature and roasts them till they're done.  If Barry is still monitoring
this list, he can respond.
I sent a copy of this post to him.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

16) From: Gene Smith
<Snip>
the
<Snip>
Thanks to Ken Mary, I now have a clue.
Ken wrote: "To be clear, you should know that the maximum airflow occurs
with the lever close to the "on" position, and at the word "roast" the
airflow is minimum and temperature is maximum."
So I went and actually held my hand over the roasting chamber without the
chaff-lid on - when it was just starting - and realized that my ears had
been deceiving me.  I had been wrongly assuming - based on the sound - that
the highest airflow was occurring at the "roast" end of the baffle/switch.
My Duhh!  I was apparently so charmed with  "To Absurdity and Beyond!" that
I was unconsciously attempting to better your claim in that department.
Gene Smith
trying not to blow so hard in Houston

17) From: Ed Needham
I 'wanted' to say what Ken said, but my Aromaroast is boxed up in the
basement and I couldn't remember what the markings were or which way the
slide went for high and low air.  I'm glad you and Ken got it figured out.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

18) From: AlChemist John
Sometime around 10:29 12/14/2003, Gene Smith typed:
<Snip>
I will do what I can.  What I am looking at right now is something that you 
would need a calculator or computer (with the algorithm provided) to use.
<Snip>
--
John Nanci 
AlChemist at large
Zen Roasting and Blending by Gestalthttp://www.dreamsandbones.net/blog/

19) From: AlChemist John
Sometime around 10:53 12/14/2003, Ed Needham typed:
<Snip>
Yes, those show a "bad" roast on my algorithm.  But as you say, those are 
obvious
<Snip>
Sort of like number theory, when I was developing this, I was making some 
base assumptions.  One was that it was a "normal" looking roast and when to 
proper temperatures.  Would not be too hard to add that kind of "limit" in.
<Snip>
Definitely catches that.
<Snip>
I will keep running numbers through and report back.
<Snip>
--
John Nanci 
AlChemist at large
Zen Roasting and Blending by Gestalthttp://www.dreamsandbones.net/blog/

20) From: AlChemist John
That is starting to make me think of my 3rd semester P. Chem, kinetics.   I 
may have to dig out that text.
Sometime around 13:01 12/14/2003, Jim Schulman typed:
<Snip>
--
John Nanci 
AlChemist at large
Zen Roasting and Blending by Gestalthttp://www.dreamsandbones.net/blog/

21) From: AlChemist John
There is nothing contradictory there.  Staub says "possibly off tastes" and 
Ken say "..and a little flat".  That seems "off" tastes.  Remember, Staub 
(and me) are meaning THE PERFECT sweet spot roast profile.  There are 
virtually infinite ways to roast and miss  this and still have the coffee 
taste great or at least good.
Sometime around 18:34 12/14/2003, Ed Needham typed:
<Snip>
--
John Nanci 
AlChemist at large
Zen Roasting and Blending by Gestalthttp://www.dreamsandbones.net/blog/

22) From: David Lewis
Note that Ken's message says that his temperatures varied between 185 
and 340. According to Staub's paper, 340 would be just touching the 
bottom end of where caramelization begins. And since Staub is 
specifically referring to the bean mass exotherming during 
caramelization, there's no contradiction at all.
Best,
	David
At 6:10 AM -0800 12/15/03, AlChemist John wrote:
<Snip>
-- 
"A designer knows he has achieved perfection not when there is 
nothing left to add, but when there is nothing left to take away."
Antoine de Saint-Exupery

23) From: Ed Needham
Good point.
Ed

24) From: David B. Westebbe
<Snip>
IME, poppers blow air at decreasing temperatures once the beans start to
swell and lighten.  This is because the air speed goes up as the
aerodynamics and mass of the beans change.
<Snip>
That's a simplified version of what I do.  I do a drying stage at 300 or so,
and then I adjust the air temp to 420 or so for the long haul.  Depending on
what I'm shooting for, I vary things a bit.  For example, there are times I
boost the heat well past 420 in order to get a faster, more vigorous crack,
and with some beans, I like to draw out first crack for a longer time.  If
the beans seeem to not be progressing as I would like, after first crack, I
sometimes boost the heat to 441 or 450.
I agree with your basic premise that this method increases the sweet spot.
However, the idea of using inlet air temps that match the desired final bean
temp appeals to me greatly, so I don't go nearly as high as 490.

25) From: Jim Schulman
On 25 Dec 2003 at 10:47, David B. Westebbe wrote:
<Snip>
If you're measuring at the bottom of the roast chamber, that's 
probably good. But one can measure anywhere from the heat coil 
itself to that point, and the temperature falls extremely 
quickly (at least on the FR, where I measured). So, the specific 
temperature settings for the ramp will depend very sensitively 
on the measuring point.
Jim

26) From: miKe mcKoffee

27) From: Jim Schulman
On 13 Jan 2004 at 8:59, miKe mcKoffee wrote:
<Snip>
The problem with the I-roast is that it doesn't ramp; it just 
blows air at three preselected temperatures. I have no idea how 
good this can be.


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