HomeRoast Digest


Topic: Internal bean temp measurements (29 msgs / 927 lines)
1) From: Randall Nortman
Alan Alder (of Aeropress and Aerobie fame) is getting into home
roasting now.  He got a Fresh Roast 8 from our hosts at Sweet Maria's
and has been playing with it.  Being the geek he is, he actually
drilled into a bean and embedded a thermocouple inside the bean, and
then roasted it and compared internal temperature to external
temperature.  His results are in the Aeropress thread over at
CoffeeGeek:http://www.coffeegeek.com/forums/coffee/machines/306079#306079Scroll up for a little more of the conversation.  (I post over there
under the handle "WonderClown".)
This answers a lot of questions I've had about internal vs. external
bean temp.  I might have to repeat the experiment myself, with
different types of beans (high-grown, peaberry, MNEB, wet process, dry
process, decaf, etc).

2) From: Randall Nortman
On Mon, Jul 09, 2007 at 11:45:36AM -0700, Robert Yoder wrote:
<Snip>
If you do the experiment enough times with different types of beans,
you can use the data to figure out how quickly heat penetrates the
bean, and then you don't actually need to internal probe anymore --
given data from just the outside probe, you could calculate (well,
estimate) the internal bean temperature.  That's moderately useful if
you have a manually controlled roaster, but a computer-controlled
roaster could do the calculations in real time and stop the roast when
it calculates that the internal bean temperature is just right.

3) From: Justin Marquez
I wonder by how much does the presence of the thermocouple in the bean
affect the temperature?  The metal has mass. The metal extends into the bean
from within the "hot zone" outside the bean - i.e., a real-world case of
"Heisenberg Uncertainty" issues. Is it more "internal bean temperature" or
more "insulating effect of coffee beans on thermocouples" ?
However, I also salute the geekery involved.
IF the measured external vs internal temperatures can be linked to actual
roast level, there could be some usefulness.  Come to think of it, if you
did that, you wouldn't need the internal temperatures now would you?
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 7/9/07, Randall Nortman  wrote:
<Snip>

4) From: raymanowen
Geek Disclaimer = Warning for geeks came to mind when I read the following:
"...geek he is, he actually-
   1. drilled into a bean and embedded a thermocouple inside the bean,
   2. and then roasted it and compared internal temperature to external
   temperature."
Step 1, above, completely changes the thermodynamic properties of the bean.
When it is drilled out, the center (innards) of the bean no longer have mass
or matter.
Step 2 involved roasting this instrumented bean with a hole and metal in it,
and could only be used once, anyway, since roasting changes the intrinsic
properties for subsequent runs.
If a wider disparity could be tolerated, a 12 pound bowling ball that has
already been drilled could be substituted, and would be easily equipped with
a thermo well to protect the thermocouple.
Come to think of it, you could put a tc in the wrist pin from a piston of an
R-4360 radial engine and roast it (the wrist pin, not the 4000hp MTO engine)
if you really haven't the slightest interest in roasting coffee.
No one else uses these methods of measuring roasting temperatures, so you
shouldn't use them either when trying to match a roast by the numbers.
Cheers -RayO, aka Opa!
On 7/9/07, Randall Nortman  wrote:
<Snip>
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita (ex- NYC Paramount) WurliTzer- 1976

5) From: Randall Nortman
On Mon, Jul 09, 2007 at 04:21:15PM -0600, raymanowen wrote:
<Snip>
He used a 40mil (0.04", 1mm) drill.  Pretty tiny.  Didn't remove much
of the bean innards.  He drilled just to the center of the bean.
Sure, it changes the bean properties slightly, and as another poster
mentioned, the thermocouple itself will conduct some heat into the
bean, but imperfect data is better than no data!  In this case, I
think it probably gets pretty darned close to the real number.
<Snip>
He does not intend to reuse the same bean over and over.  He said the
process of drilling it was quite simple.  I assume he has a drill
press.  Anyway, you don't do it on EVERY roast -- you do it a few
times until you have enough data that you can calculate (estimate) the
heat transfer in the bean (as I mentioned before), and then you never
have to do it again.

6) From: Floyd Lozano
Given all the variables, such as bean moisture, bean density, bean count,
bean shape, air flow, roasting container characteristics, ambient
temperature and whatever else I didn't think of, I think that precise
computation of 'doneness' is akin to predicting earthquakes or weather
changes.  I think it will one day be solvable (in fact, when we design heat
resistant nanomachines that can communicate wirelessly through a roasting
vessel and burrow into the center of a bean, it's pretty much a done deal)
And you have to figure, where's the center of a bean?  It's kind of folded
up - when you munch one, the cross section (of many of mine at least) has a
bit of air space in there.  What a wondrous mystery is our hobby!
-F
On 7/9/07, Randall Nortman  wrote:
<Snip>

7) From: Tom Ogren
What a wondrous mystery is our hobby!
-F
"There is a very fine line between "hobby" and "mental illness."
-Dave Barry
I admit that I really love the idea behind Adler's experiment, but
tend to agree that the drill-out and insertion of bare metal into the
bean must throw things out of whack, particularly with the variability
of density and relative moisture from one varietal (or lot) to the
next. Cool idea nonetheless.
TO in VA
On 7/10/07, Floyd Lozano  wrote:
<Snip>

8) From: Scott Marquardt
I think a fairly unobtrusive thermocouple experiment could be done using a
much smaller hole and a very tiny thermocouple.
The problem is one of time and effort. IMO, in order to do this right you'd
need to have a hole bored all the way through the bean, with each lead of
the junction coming from opposite ends of that hole through the bean, welded
in the middle with a join no larger than the wire diameter. The hole would
need to be very snug on this wire, and this snugness would have to be
certifiably maintained throughout the roast cycle.
A huge challenge would be to insulate the wires where they emerge from the
bean, in order to prevent conduction of heat to the junction through the
wires themselves. That conduction would be rapid -- and though a snug fit in
the hole could sink some of that heat away into the bean before it reached
the core, that would still be a biasing result. IMO, some kind of barrier at
each end of the bean would be necessary, to prevent heated air from heating
the wire. However, then the barrier becomes a variable to control for. Etc.
Tough problem.
On 7/10/07, Tom Ogren  wrote:
<Snip>

9) From: Edward Bourgeois
The question is how this info can be useful. Is the goal at the end of
a roast to have the same agtron measurement on the outside as the
grind measurement. If the outside is to be x amount darker than the
grinds at what point or points in the roast should this be obtained by
roasting the external faster than can be transferred internally.
Should this variance be obtained quickly or slowly. When ramping up
temp say before first crack how much internal increase (degrees/min.)
is needed or possible without over scorching the external.
On 7/10/07, Tom Ogren  wrote:
<Snip>

10) From: Brett Mason
Another method is to roast the beans,
measure bean mass temperature as a whole
photograph and document the roast,
rest for three days
consume and comment.
After a few tries, the process should be repeatable and reliable, even
without soldering...
Brett
On 7/10/07, Edward Bourgeois  wrote:
<Snip>
-- 
Cheers,
Bretthttp://homeroast.freeservers.com

11) From: Barry Luterman
This is a multi-part message in MIME format.
Or more succinctly. Why change an art into a science?

12) From: Jim Carter
This is a multi-part message in MIME format.
As usual in these discussions, everybody leaves out the all-important 
final step of the process -- the bowel movement.
After a few tries, the process should be repeatable and reliable, even 
without soldering...
-- JC
Brett Mason wrote:
<Snip>

13) From: Randall Nortman
On Tue, Jul 10, 2007 at 08:25:27AM -1000, Barry Luterman wrote:
<Snip>
Because art is hard.

14) From: miKe mcKoffee
AND because virtually all phases of coffee take both Art & Science for the
best results.
Pacific Northwest Gathering VIhttp://home.comcast.net/~mckona/PNWGVI.htmKona Kurmudgeon miKe mcKoffee
URL 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.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/
 
<Snip>
<Snip>
<Snip>

15) From: Kris McN
Science is hard too.http://www.theonion.com/content/node/38575Kris McN
On 7/10/07, Randall Nortman  wrote:
<Snip>

16) From: Barry Luterman
I am surprised as a cook you would say that. I trust my nose and hearing 
much more than a Variac or temp probe. I know your chicken has KFC beat by a 
mile. KFC is very scientific. If one goes into a KFC in any town the chicken 
tastes the same.However, the chicken never tastes as good as at your house. 
If we are to speak about coffee Starbucks uses very scientific roasting and 
brewing methods. Little is left for art for their teenage baristas.

17) From: Justin Nevins
Ah, but Mike said, "virtually all phases of coffee take both Art & Science
for the best results."
He probably does trust his nose & hearing more, but recognizes that a variac
and temp probe can contribute marginally to better roasting.
Justin Nevins
On 7/10/07, Barry Luterman  wrote:
<Snip>

18) From: miKe mcKoffee
This is a multi-part message in MIME format.
Exactly. Was Leonardo da Vinci a great artist or a great scientist? The
answer is "yes", both. IMO better understanding of the science enables
better application of the art.
 
For instance science might say X food should be cooked to Y temperature. The
art is how to take X to Y creatively.
 
Pacific Northwest Gathering VIhttp://home.comcast.net/~mckona/PNWGVI.htmKona Kurmudgeon miKe mcKoffee
URL 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.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/ 
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Justin Nevins
Sent: Tuesday, July 10, 2007 2:05 PM
Ah, but Mike said, "virtually all phases of coffee take both Art & Science
for the best results." 
He probably does trust his nose & hearing more, but recognizes that a variac
and temp probe can contribute marginally to better roasting.
Justin Nevins
On 7/10/07, Barry Luterman  wrote: 
I am surprised as a cook you would say that. I trust my nose and hearing
much more than a Variac or temp probe. I know your chicken has KFC beat by a
mile. KFC is very scientific. If one goes into a KFC in any town the chicken
tastes the same.However, the chicken never tastes as good as at your house.
If we are to speak about coffee Starbucks uses very scientific roasting and
brewing methods. Little is left for art for their teenage baristas.

19) From: Barry Luterman
This is a multi-part message in MIME format.
If science designed the perfect roaster one that measured and adjusted =
for every known variable and everyone had access to that one machine I =
predict there would still be people who could make better coffee than =
that machine. They would be on this list and we would all refer to them =
as master roasters. Science will never replace art it will just level =
the playing field somewhat. I would rather have chicken and coffee at =
MiKe's house than KFC or *$. Even though no matter where I am the =
products will be consistent. All Science can do is assure reliability =
(repeatability) not art.

20) From: miKe mcKoffee
This is a multi-part message in MIME format.
Ah, such roasters do exist commercially now. The "art" is not lost as the
Roast Master "tells"  the machine (roaster) what to do "automatically" AFTER
perfecting a given profile for a given bean. As in programs the roast
control system, which can be completely automated programming via recording
the manual roast sessions. And in my roaster search/research for the Kafe
one of the requirements is ability to have automated control system added
later. (For many many $k more:-)
 
Pacific Northwest Gathering VIhttp://home.comcast.net/~mckona/PNWGVI.htmKona Kurmudgeon miKe mcKoffee
URL 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.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/ 
From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Barry Luterman
Sent: Tuesday, July 10, 2007 3:23 PM
 
 If science designed the perfect roaster one that measured and adjusted for
every known variable and everyone had access to that one machine I predict
there would still be people who could make better coffee than that machine.
They would be on this list and we would all refer to them as master
roasters. Science will never replace art it will just level the playing
field somewhat. I would rather have chicken and coffee at MiKe's house than
KFC or *$. Even though no matter where I am the products will be consistent.
All Science can do is assure reliability (repeatability) not art.

21) From: Randall Nortman
Science can provide better tools to the artist.  You could roast your
beans over a campfire in a flat metal pan if you like, but you
probably choose to use something slightly more sophisticated.  Even
then, controlled fire and a metal pan would both be provided to you,
the artist, compliments of science and technology (aka human
ingenuity).  Now granted, gas BBQ drum roasters are really pretty
darned close to roasting in a pan over an open fire, but it's the
little things that make a big difference in terms of convenience and
repeatability.
In my ideal roaster, my job as an artist would be in crafting the
perfect roasting profile, and then using my tools (a really smart
roaster) to execute that vision, probably more faithfully than I could
myself.
KFC and *$ use science to craft a consistent product as cheaply as
possible, with just enough quality to keep their customers coming
back.  Science can also be used to help make the highest quality
product possible, but that's just not how they use it -- they are more
concerned with cost.  I think they (and other such companies) do a
really remarkable job of providing a highly consistent product with an
acceptable (to most) level of quality for low prices.  (Well, *$
misses the mark on the price to the end consumer, actually, but
largely because they have to pay for all that prime retail real
estate, and still produce enough profit to support their unsupportable
growth.  I suspect the coffee itself represents a rather small portion
of their operating expenses.)
On Tue, Jul 10, 2007 at 12:23:07PM -1000, Barry Luterman wrote:
<Snip>

22) From: Duncan
On Tue, 10 Jul 2007 18:58:22 -0400, Randall Nortman  wrote:
<Snip>
Hey, everyone, I'm new to this list and the home roasting thing but loving both so far. I just have to leap in on this and and my 2¢.
Science can and has been used to improve food and food quality, but it has to be used creatively. A place that the two meet is espresso. Grounds should be tamped at 30 pounds pressure, then polished at 20 pounds. The water is at 92-96°C needs to be forced through grounds at 9-10 atmospheres and extraction should take 25-30 seconds. I'm leaving off the grind here because the "correct" grind varies as per grinder and espresso maker. The art comes from selecting the beans, roasting them correctly for the beans and the resulting brew, the experience that tells you how to adjust variables to improve the espresso. 
Science is a tool and should be used as such. It can be used to assist in the production of great coffee, or assist in the production of bad coffee.
Either way, you're isolating variables and attempting to control them for a desired result - that's the science. The art comes from having done enough roasts adjust variables on the fly, without needing anything beyond the five senses. The maillard reaction still happens and the coffee still tastes good.
Hope I haven't gotten too far off-topic.
Duncan

23) From: Lynne Biziewski
<Snip>
Randall, I have to disagree w/you on that. In my opinion, it is advertising
-
PR - that they use to keep people coming back.
L.

24) From: raymanowen
"KFC and *$ use science to craft a consistent product as cheaply as
possible..."
So does any business. Stop right there! -ro

25) From: Alchemist John
Both is very true IMO.  In this case though, I don't see the 
practical application at all (although I appreciate the intrinsic 
gathering of data and science done).
Consider it this way - If the internal temperature at 1st or 2nd (x 
or x') correlates to an external temperature of the bean "with enough 
data" (y), then y correlates to the external temperature at 1st or 
2nd.  Why bother with x's at all except for novelty sake?  Its a no 
win situation to measure the internal temperature.  Either a) it 
correlates and you can use the external temperature or b) it doesn't 
correlate in which all you have gained is the knowledge that external 
temperature doesn't correlate.  You can't get internal temperature on 
a day to day basis.
At 14:34 7/10/2007, you wrote:
<Snip>
John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/

26) From: Randall Nortman
On Wed, Jul 11, 2007 at 05:38:16AM -0700, Alchemist John wrote:
<Snip>
Ah, but it won't correlate very well with just plain external
temperature, because the ramp rate is also critical.  If you ramp the
external temperature at 80F/min you will see a large differential
between internal and external (I'm assuming), but if you hold external
temperature at 430F steady, then eventually the internal temp will
come to 430F.  How big will that differential be with the 80F/min ramp
rate?  How quickly will the interior come to 430F with the
constant-temp soak?  That's where this data comes in.  What the data
allows you to do is model all of this (or rather, let a computer model
all of it).  Input into the model is not just one external temperature
reading, but the whole curve from the start of the roast.  Only then
can you get any decent guess at what the internal temperature actually
is.
So what it does is take into account not only final external
temperature but also how you got there -- the entire profile -- to
tell you what is happening inside the bean.  You can combine that with
whatever rudimentary knowledge we have of the chemical changes and how
quickly they progress at different temperatures to keep the internal
bean temperatures where you want them for the optimal reaction rates.
In theory.

27) From: Justin Marquez
But science can get expensive.
Safe Journeys and Sweet Music
Justin Marquez (CYPRESS, TX)
On 7/10/07, Randall Nortman  wrote:
<Snip>

28) From: Larry Johnson
Advertising may be described as the science of arresting the human
intelligence long enough to get money from it.  -  Stephen Leacock
On 7/10/07, Lynne Biziewski  wrote:
<Snip>
-- 
Larry J
Whatever you do will be insignificant, but it is very important that you do
it.
  - Mahatma Gandhi

29) From: John Moody
Funny as hell Ray, thanks.
What about a bean-sized ceramic that could be soaked overnight in water?  I
ll bet Mr. Scace could engineer a pretty good approximation to an average
bean if he wanted to; and many of us would find it useful to compare notes
in our pursuit of the ultimate......
John


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