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Main
Date: 19 Jun 2006 08:43:57
From: TimEggers
Subject: Get "MET" it pays...
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After the long and informational discussion sparked by Mr. Jim Schulman
(http://groups.google.com/group/alt.coffee/browse_thread/thread/04c5030a590ad400)
about Maximum Environmental Temperatures per Mr. Carl Staub's writings
I have really changed my roasting approach and for the better.
Currently I roast in a BBQ with the RK Drum, and previously I was under
the flawed conception that my times should match the times most likely
produced in a commercial drum machine. My coffee was very "blah" and I
found it to be quite lacking not only in flavor but also in aroma.
I was roasting very hot (650F) pre-first crack (FC) and then cooling
the grill post FC. After several batches with a lower MET inside the
grill, not the drum, I can really appreciate the importance of MET.
With a two-pound load I can keep the MET below 520F (really around
515F) and reach FC in 12-13 minutes then I reduced the heat a little
and found Full City (a few snaps of second) at17 minutes. The coffee
an Ethiopian Wet Processed Sidamo has a very good-fruited complexity
with raisin/plum notes. More notably the aroma is really nice and
intense, both in dry bean form and brewed coffee. This is after a mere
24 hours rest. I can't wait to evaluate the coffee over the coarse of
the next several days.
Now I know the coffee is better and I am trying (in my limited mind) to
understand what I have been doing and why it has been working as well
as it appears to be. I think it has to do with matching application of
heat (BTU) to available airflow to produce the desired transfer rate to
meet roast level requirements in an optimum timeframe. Wow, did I
really spew all that? Anyway basically it means that for a bbq where
airflow is much different than a commercial drum a different
temperature has to be used (a higher MET versus batch size, after all
520F is awfully warm for a small 2lb load) but it is needed to produce
the speed of roast (rate of thermal transfer) to hit the best target
times for best coffee results. In reverse this is why a fluid bed
machine can use lower temps while still getting optimum times because
the thermal transfer is much faster due to the use of airflow.
In review in you opinion does roast success regardless of method used
mean matching application of BTU to airflow in order to produce the
optimum times (via a good thermal transfer rate)? I was trying to get
times that are too fast for a bbq set up by using a very high MET. Now
I have learned that slower times are better with a lower MET when using
a bbq because the airflow is much lower than a commercial drum machine
however at the same time because the airflow is less a higher MET in
relation to charge weight must be used to reach target times. I wonder
if a commercial machine using a 2lb batch really has to go clear to
520F MET to reach optimum times? I sure do when using a bbq setup.
Thoughts?
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Date: 19 Jun 2006 21:55:55
From: TimEggers
Subject: Re: Get "MET" it pays...
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Ken Fox wrote:
> "TimEggers" <timeggers@hotmail.com> wrote in message
> news:1150731837.086138.72950@r2g2000cwb.googlegroups.com...
> > After the long and informational discussion sparked by Mr. Jim Schulman
> > (http://groups.google.com/group/alt.coffee/browse_thread/thread/04c5030a590ad400)
> > about Maximum Environmental Temperatures per Mr. Carl Staub's writings
>
> <total snippage>
>
> Could it be that the gentleman is completely FOS?
>
> Meaning no offense to anybody, it appears to this uneducated home roaster as
> if people get good and bad results all the time and it is very hard to
> compare results obtained in one roaster to another whilst assuming that a
> given temperature measured in one roaster is comparable to the same temp
> measured in another. Exactly how any measured temperature actually reflects
> upon the elusive "internal bean temperature" is yet another issue.
>
> My opinion is that every roaster has its own behavior, its own profile that
> will produce the best results for that roaster; trying to extrapolate
> results from one roaster to another is very dicey business. Some of this is
> due to measurement errors or peculiarities, some is due to characteristics
> (only some of which we understand) of each roaster, and some of this is just
> stuff we don't know.
>
> I think we are trying to reduce a very complicated process with many
> variables to one or two numbers and then trying to make sense of it; this is
> impossible.
>
> My advice would be to try all the possible profiles you can easily get with
> your equipment, taste the results, and then try to emulate the roast that
> produced the best results. Of course, "best results" are an ever moving
> target so you are going to have to continually work on these parameters if
> you want the best coffee you can produce.
>
> The rest is BS.
>
> ken
Hello again Mr. Fox. I think you raise some very good points in your
comments however I still have a desire to better understand why the
things I do produce the results they do. True that information and
especially my readings are of no use to anyone else especially on their
machines but I still enjoy the discussion and the learning that I have
been fortunate enough to gain from others here and abroad. Coffee
roasting is no doubt a very complex (to be trite) event. I especially
will never have a true understanding of it but I still have a drive to
go as far as I can.
In the end I really agree with your comments about experimentation and
data recording. I try different things and I take notes as best I can.
Home roasting is a process in of itself and one I quite enjoy. These
discussions just season the experience even more. Thank you all.
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Date: 19 Jun 2006 20:24:00
From: Ken Fox
Subject: Re: Get "MET" it pays...
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"TimEggers" <timeggers@hotmail.com > wrote in message
news:1150731837.086138.72950@r2g2000cwb.googlegroups.com...
> After the long and informational discussion sparked by Mr. Jim Schulman
> (http://groups.google.com/group/alt.coffee/browse_thread/thread/04c5030a590ad400)
> about Maximum Environmental Temperatures per Mr. Carl Staub's writings
<total snippage >
Could it be that the gentleman is completely FOS?
Meaning no offense to anybody, it appears to this uneducated home roaster as
if people get good and bad results all the time and it is very hard to
compare results obtained in one roaster to another whilst assuming that a
given temperature measured in one roaster is comparable to the same temp
measured in another. Exactly how any measured temperature actually reflects
upon the elusive "internal bean temperature" is yet another issue.
My opinion is that every roaster has its own behavior, its own profile that
will produce the best results for that roaster; trying to extrapolate
results from one roaster to another is very dicey business. Some of this is
due to measurement errors or peculiarities, some is due to characteristics
(only some of which we understand) of each roaster, and some of this is just
stuff we don't know.
I think we are trying to reduce a very complicated process with many
variables to one or two numbers and then trying to make sense of it; this is
impossible.
My advice would be to try all the possible profiles you can easily get with
your equipment, taste the results, and then try to emulate the roast that
produced the best results. Of course, "best results" are an ever moving
target so you are going to have to continually work on these parameters if
you want the best coffee you can produce.
The rest is BS.
ken
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Date: 19 Jun 2006 18:45:37
From: Erik Groomer
Subject: Re: Get "MET" it pays...
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Erik Groomer wrote:
> I don't get it. You quote: "> "The ideal environmental temperature, ET,
> for best reaction ratio, BRR, is
> > from -401-424 degrees F, with 405 degrees F as the default value. " and yet he explicitly says "The ideal ENVIRONMENTAL TEMPERATURE". Sorry, didn't mean to shout, I just want to understand.
Perhaps he is roasting just into first crack?
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Date: 19 Jun 2006 18:39:54
From: Erik Groomer
Subject: Re: Get "MET" it pays...
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Johnny wrote:
> My take on that is that he meant bean temp for BRR rather than ET.
> Why? because earlier he says:
> "Trigonelline melts in it's pure crystalline form at 424 degrees F
> Degradation of trigonelline begins at approximately 378 degrees F.."
>
> and when defining the BRR as being about "degradation of trigonelline" he
> says:
> "The ideal environmental temperature, ET, for best reaction ratio, BRR, is
> from -401-424 degrees F, with 405 degrees F as the default value. "
>
> its that 424 upper end that makes me conjecture that .
I don't get it. You quote: " > "The ideal environmental temperature, ET,
for best reaction ratio, BRR, is
> from -401-424 degrees F, with 405 degrees F as the default value. " and yet he explicitly says "The ideal ENVIRONMENTAL TEMPERATURE". Sorry, didn't mean to shout, I just want to understand.
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Date: 19 Jun 2006 18:53:19
From: Johnny
Subject: Re: Get "MET" it pays...
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"Erik Groomer" <ViridianCoffee@gmail.com > wrote in message
news:1150767594.451931.166930@r2g2000cwb.googlegroups.com...
>
> Johnny wrote:
>
> > My take on that is that he meant bean temp for BRR rather than ET.
> > Why? because earlier he says:
> > "Trigonelline melts in it's pure crystalline form at 424 degrees F
> > Degradation of trigonelline begins at approximately 378 degrees F.."
> >
> > and when defining the BRR as being about "degradation of trigonelline"
he
> > says:
> > "The ideal environmental temperature, ET, for best reaction ratio, BRR,
is
> > from -401-424 degrees F, with 405 degrees F as the default value. "
> >
> > its that 424 upper end that makes me conjecture that .
>
> I don't get it. You quote: "> "The ideal environmental temperature, ET,
> for best reaction ratio, BRR, is
> > from -401-424 degrees F, with 405 degrees F as the default value. " and
yet he explicitly says "The ideal ENVIRONMENTAL TEMPERATURE". Sorry, didn't
mean to shout, I just want to understand.
>
I was thinking he made a typographical error.
But now I've rethought that and maybe he actually said what he meant ;-)
Perhaps it is that the BRR is a stage in the process, whereas MET would
seem to be an end point ET.
You could do 401-424 on the way there.
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Date: 19 Jun 2006 15:37:38
From: Erik Groomer
Subject: Re: Get "MET" it pays...
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> > >Thoughts?
> >
> > The taste change sounds more like you were violating another one of
> > Staub's rule (this one I'm fairly sure about, since it accords with my
> > experience). That is, don't reduce the Met during the roast, otherwise
> > the flavor compunds polymerize, and the flavor goes flat. This sounds
> > like your improvement. Reducing too high a Met usually improves the
> > taste by reducing prickly acrid and burnt notes.
Jim,
I thought that Staub was saying that once caramelization begins you
don't want to allow the bean mass to exotherm. I read what you said
about not reducing MET during the roast and I was confused. Is there
more to what you are saying that I am not understanding? Couldn't you
reduce the MET and yet not stall the roast?
Since Staub has been brought up again can I bring up Best Reaction
Ratio? He says:
" There is a window of reaction rates that will optimize cup quality.
This is called the Best Reaction Ratio, or BRR...The ideal
environmental temperature, ET, for best reaction ratio, BRR, is from
-401-424 degrees F, with 405 degrees F as the default value. The BTU
required is determined by the systems transfer efficiency, or ability
to impart the energy to the charge mass...Consequently, the MET should
not exceed 520 degrees F."
What I don't understand is Staub's claim that BRR is around 405F but
over and against that that MET should not be above 520. Could someone
please explain the apparent contradiction? I must be missing something.
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Date: 19 Jun 2006 21:03:21
From: jim schulman
Subject: Re: Get "MET" it pays...
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On 19 Jun 2006 15:37:38 -0700, "Erik Groomer"
<ViridianCoffee@gmail.com > wrote:
>What I don't understand is Staub's claim that BRR is around 405F but
>over and against that that MET should not be above 520. Could someone
>please explain the apparent contradiction? I must be missing something.
I don't understand that part either; it's, as Martin says, rather
tough to sort out exactly what temperature he's talking about, never
mind measuring it.
I have an admittedly simple roaster: hot air goes in at one end and,
having heated the beans, comes out cooler at the other. I measure it
at both ends, and after four years or so of doing this on every roast,
I can definitely say bad things happen when the temperature drops on
either end during the roast. I came on this after reading Staub's
piece; by now I have so much empirical confirmation, that I'm not all
that interested anymore whether this is exactly what he had in mind.
In any case, Tim's experience seems more akin to the flattened taste I
get if the temperatures do drop.
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Date: 19 Jun 2006 18:31:34
From: Johnny
Subject: Re: Get "MET" it pays...
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"Erik Groomer" <ViridianCoffee@gmail.com > wrote in message
news:1150756658.171034.279690@h76g2000cwa.googlegroups.com...
> ...
> Since Staub has been brought up again can I bring up Best Reaction
> Ratio? He says:
> " There is a window of reaction rates that will optimize cup quality.
> This is called the Best Reaction Ratio, or BRR...The ideal
> environmental temperature, ET, for best reaction ratio, BRR, is from
> -401-424 degrees F, with 405 degrees F as the default value. The BTU
> required is determined by the systems transfer efficiency, or ability
> to impart the energy to the charge mass...Consequently, the MET should
> not exceed 520 degrees F."
>
> What I don't understand is Staub's claim that BRR is around 405F but
> over and against that that MET should not be above 520. Could someone
> please explain the apparent contradiction? I must be missing something.
>
My take on that is that he meant bean temp for BRR rather than ET.
Why? because earlier he says:
"Trigonelline melts in it's pure crystalline form at 424 degrees F
Degradation of trigonelline begins at approximately 378 degrees F.."
and when defining the BRR as being about "degradation of trigonelline" he
says:
"The ideal environmental temperature, ET, for best reaction ratio, BRR, is
from -401-424 degrees F, with 405 degrees F as the default value. "
its that 424 upper end that makes me conjecture that .
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Date: 19 Jun 2006 19:23:58
From: Ed Needham
Subject: Re: Get "MET" it pays...
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Long chain polymers connect in ways that do not make for great tasting
coffee if the 'bean temps' are allowed to fall during the roast.
--
*********************
Ed Needham®
"to absurdity and beyond!"
ed at homeroaster dot com
(include [FRIEND] in subject line to get through my SPAM filters)
*********************
"Erik Groomer" <ViridianCoffee@gmail.com > wrote in message
news:1150756658.171034.279690@h76g2000cwa.googlegroups.com...
> Jim,
> I thought that Staub was saying that once caramelization begins you
> don't want to allow the bean mass to exotherm. I read what you said
> about not reducing MET during the roast and I was confused. Is there
> more to what you are saying that I am not understanding? Couldn't you
> reduce the MET and yet not stall the roast?
<SNIP >
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Date: 20 Jun 2006 13:51:18
From: Brent
Subject: Re: Get "MET" it pays...
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What about double roasting?
> Long chain polymers connect in ways that do not make for great tasting
> coffee if the 'bean temps' are allowed to fall during the roast.
> --
> *********************
> Ed Needham®
> "to absurdity and beyond!"
> ed at homeroaster dot com
> (include [FRIEND] in subject line to get through my SPAM filters)
> *********************
>
>
> "Erik Groomer" <ViridianCoffee@gmail.com> wrote in message
> news:1150756658.171034.279690@h76g2000cwa.googlegroups.com...
>> Jim,
>> I thought that Staub was saying that once caramelization begins you
>> don't want to allow the bean mass to exotherm. I read what you said
>> about not reducing MET during the roast and I was confused. Is there
>> more to what you are saying that I am not understanding? Couldn't you
>> reduce the MET and yet not stall the roast?
> <SNIP>
>
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Date: 20 Jun 2006 01:04:15
From: Ed Needham
Subject: Re: Get "MET" it pays...
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Some have good success with double roasting. I have not found it to improve
a roast, but it has saved a roast or two from being terrible. Once when my
propane tank went dry and I had to stop the roast just after first crack.
Another when I purposely experimented with double roasting. I'd say
something was 'off' in each roast.
I'd imagine that Staub has been wrong more than once in his life. If it
works, then do it. If not, then stop.
--
*********************
Ed Needham®
"to absurdity and beyond!"
ed at homeroaster dot com
(include [FRIEND] in subject line to get through my SPAM filters)
*********************
"Brent" <me@privacy.net > wrote in message
news:4fp1orF1jn4tgU1@individual.net...
> What about double roasting?
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Date: 19 Jun 2006 12:08:39
From: Heat + Beans
Subject: Re: Get "MET" it pays...
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Even though we are all mindful of the distinctions, in practice it is
pretty easy to conflate MET, ET, actual bean temperature, and
temperature lag for each of these as the roaster raises or lowers the
input of heat. Particularly confounding is the beans' exothermic
reaction at some point after 1st c, which means that the roaster can
reduce the BTUs going into the roast as the temp within the bean mass
continues to rise.
Observation about the cfm factor. Early in the roast, high cfm can
speed heat transfer to beans, but once the beans become exothermic,
higher cfm appears not to have that effect and higher airflow at a
consistent temp may "carry away" as much much heat as it contributes.
I suppose it boils down to how many metrics the roaster can both
control and keep track of--keeping in mind that the addition of
variables, IMO, increases complexity in a way that is not linear, but
closer to geometric. As a strictly personal example, Jim's MET
reporting so far is useful to me because it confirms Staub's broadest
admonition not to become so fixated on the profile numbers as to forget
about what's going on within the bean.
Martin
jim schulman wrote:
> On 19 Jun 2006 08:43:57 -0700, "TimEggers" <timeggers@hotmail.com>
> wrote:
>
> >Thoughts?
>
> The taste change sounds more like you were violating another one of
> Staub's rule (this one I'm fairly sure about, since it accords with my
> experience). That is, don't reduce the Met during the roast, otherwise
> the flavor compunds polymerize, and the flavor goes flat. This sounds
> like your improvement. Reducing too high a Met usually improves the
> taste by reducing prickly acrid and burnt notes.
>
> I'm guessing the very high drum temps at the beginning of the roast
> didn't harm the bean (they can take a lot of heat until the first
> crack). Instead, it seems that cooling off the grill to get a slow
> enough roast finish also reduced the temperature inside the drum and
> led to the flatter taste.
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Date: 19 Jun 2006 11:49:13
From: TimEggers
Subject: Re: Get "MET" it pays...
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Mr. Schulman a pleasure as always. Your point is well taken (I am
still trying to figure things out I must admit). However I am faced
with a dilemma as you see currently with a two-pound batch I have to
set the MET in the grill to 515F-520F fairly early in the roast (4-5
minutes) just to reach FC in 12-13 minutes.
That's not the problem though however rather just before first crack
the MET will spike by 10 or so degrees sometimes more. Should I let
the spike occur or should I compensate by lowering BTU in order to
maintain the 515F-520F MET?
Currently I lower BTU to maintain the 515F-520F and I don't let the MET
drop at all until the finish of the roast. The good news is that at a
MET of 520F I will get FC at 12-13 minutes and a few pops of SC at
16-17 minutes. I really like those times and as you state not lowering
the MET post FC seems to be a good thing based on my own results.
Again these are temperatures inside the grill but outside the drum. I
would speculate that the temps are slightly cooler in the drum, but
without any probe I can't be sure of that.
In the end however the coffee is much better and again I am reminded of
what I have yet to learn and what a rewarding experience this can
really be.
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Date: 19 Jun 2006 12:24:40
From: jim schulman
Subject: Re: Get "MET" it pays...
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On 19 Jun 2006 08:43:57 -0700, "TimEggers" <timeggers@hotmail.com >
wrote:
>Thoughts?
The taste change sounds more like you were violating another one of
Staub's rule (this one I'm fairly sure about, since it accords with my
experience). That is, don't reduce the Met during the roast, otherwise
the flavor compunds polymerize, and the flavor goes flat. This sounds
like your improvement. Reducing too high a Met usually improves the
taste by reducing prickly acrid and burnt notes.
I'm guessing the very high drum temps at the beginning of the roast
didn't harm the bean (they can take a lot of heat until the first
crack). Instead, it seems that cooling off the grill to get a slow
enough roast finish also reduced the temperature inside the drum and
led to the flatter taste.
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Date: 19 Jun 2006 18:15:39
From: Johnny
Subject: Re: Get "MET" it pays...
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"jim schulman" <jim_schulman@ameritech.net > wrote in message
news:v1nd92500ii2m3l74lhd7svqqokvjeavi3@4ax.com...
> On 19 Jun 2006 08:43:57 -0700, "TimEggers" <timeggers@hotmail.com>
> wrote:
>
> >Thoughts?
>
> The taste change sounds more like you were violating another one of
> Staub's rule (this one I'm fairly sure about, since it accords with my
> experience). That is, don't reduce the Met during the roast,
That makes no sense Jim.
How do you reduce an already achieved _maximum_ during the roast?
Surely you meant just ET?
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Date: 19 Jun 2006 21:08:21
From: jim schulman
Subject: Re: Get "MET" it pays...
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On Mon, 19 Jun 2006 18:15:39 -0700, "Johnny"
<removethis.huuanito@hotmail.com > wrote:
>How do you reduce an already achieved _maximum_ during the roast?
>Surely you meant just ET?
Most likely. I've been using Met as the highest temperature the beans
come into contact with at any moment. By my use, the Met changes
throughout the roast. ET is inherently ambiguous, since the
environment includes everything from the flame or electric element to
the ambient temperature of the room or outdoors (i.e the thermodynamic
source and sink of the roast process)
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Date: 19 Jun 2006 20:27:31
From: Johnny
Subject: Re: Get "MET" it pays...
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"jim schulman" <jim_schulman@ameritech.net > wrote in message
news:itle92df5kv3k18uncmdt6gtpc6hjh4ah3@4ax.com...
> On Mon, 19 Jun 2006 18:15:39 -0700, "Johnny"
> <removethis.huuanito@hotmail.com> wrote:
>
> >How do you reduce an already achieved _maximum_ during the roast?
> >Surely you meant just ET?
>
> Most likely. I've been using Met as the highest temperature the beans
> come into contact with at any moment. By my use, the Met changes
> throughout the roast. ET is inherently ambiguous, since the
> environment includes everything from the flame or electric element to
> the ambient temperature of the room or outdoors (i.e the thermodynamic
> source and sink of the roast process)
huh? Why is MET (maxumum environment tempeature) unambiguous but ET
(environment tempeature) "inherently ambiguous"?
unless we are somehow leaping to different environments it is presumably the
very same environment in both cases. I take that to be the environment
temperature measured at the same location, around about the bean. As in, the
environmental temperature, in the environs of the bean. We could by your
definition extend the environment ad infinitum, I regard it somewhat more
locally, by the bean.
Staub has a paragraph on environment temperature and uses the ET abreviation
for that in the paragraph on BRR. I don't think he is referring to the
outdoors..
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Date: 20 Jun 2006 00:20:30
From: jim schulman
Subject: Re: Get "MET" it pays...
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On Mon, 19 Jun 2006 20:27:31 -0700, "Johnny"
<removethis.huuanito@hotmail.com > wrote:
>huh? Why is MET (maxumum environment tempeature) unambiguous but ET
>(environment tempeature) "inherently ambiguous"?
Because beans have volume and take up space. Every point of that space
has a temperature, and presumably they are not all the same. The
maximum temperature of this set is unique (at least, it was when I
took analysis). The piece is not about measurement or the difficulties
of getting temperatures, trigonelline breakdown ratios, etc. etc.,
rather it is about roasting chemistry. if he's using the terms based
on conventional temperature measurements, rather than the set of
conditions pertaining throughout the roaster, nothing he says makes
any sense.
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Date: 20 Jun 2006 01:08:47
From: Johnny
Subject: Re: Get "MET" it pays...
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"jim schulman" <jim_schulman@ameritech.net > wrote in message
news:911f92t2du81be68safmkm6q8glc0j7u26@4ax.com...
> On Mon, 19 Jun 2006 20:27:31 -0700, "Johnny"
> <removethis.huuanito@hotmail.com> wrote:
>
> >huh? Why is MET (maxumum environment tempeature) unambiguous but ET
> >(environment tempeature) "inherently ambiguous"?
>
> Because beans have volume and take up space.
How does this make them in a different environment in one case (MET) from
the other(ET)?
They are still there in the same place. It is the same environment yet you
find one (ET) ambiguous but the other (MET).
> Every point of that space
> has a temperature, and presumably they are not all the same.
Agreed.
However the space taken by the beans is not the environment, the
environment is outside the beans, it surrounds them. Usually the environment
is the air around the beans and also when they are contacting the drum
surface that becomes a part of the environment also.
>The
> maximum temperature of this set is unique (at least, it was when I
> took analysis).
Sure. But there's just the one maximum. Set or no set. If there's a place in
the local environment that is at the maximum temperature for that
environment then that is the MET. If a subsequent temperature exceeds that
then the previous maximum is no more, there's a new kid on the block.
As you write, that's what a maxiumum is, a single largest point. Unique by
definition. Which of course was the point of my original disagreement with
what you wrote about changing MET during a roast. The MET that is reached
during a roast is the maximum of a set of all the instantaneous maxiumum
temperatures reached during the roast, as you point out, unique.
Either way, you go over the 520F and there's no going back.. It's a done
deal.
> The piece is not about measurement or the difficulties
> of getting temperatures, trigonelline breakdown ratios, etc. etc.,
> rather it is about roasting chemistry.
Agreed. It's about roasting chemistry and the effect of roasting environment
temperatures thereon. Sounds like we may have been reading the same article
:-)
> if he's using the terms based
> on conventional temperature measurements, rather than the set of
> conditions pertaining throughout the roaster, nothing he says makes
> any sense.
He makes no mention of temperature measurements, conventional or otherwise.
He refers only to environmental temperatures and their effects on the
chemistry. There is however a comment within one paragraph about monitoring
bean temperature but still no means suggested.
If by "throughout the roaster" you are referring to conditions outside of
the immediate surroundings of the beans, i.e., the roast chamber, then I
disagree. Outside the roast chamber conditions affect the roasting
environmental temperatures only indirectly.
It is the set of environmental conditions in the immediate surroundings of
the beans that determine the heat transfer that takes place. The heat
transfer is what raises the temperature of the beans and "determines the
specific types of chemical reactions that occur" and that heat transfer
takes place in the immediate vicinity of the beans, not throughout the
roaster, it's very local to where the beans are.
It takes place at a rate determined by the usual 'heat exchange is
proportional to temperature difference'. Since it is from the immediate
surroundings that the beans draw the heat, it is in this nearest
environment that he is recommending not to exceed a maximum of 520F.
Anywhere else makes no sense.
|
| | | |
Date: 20 Jun 2006 13:53:22
From: Brent
Subject: Re: Get "MET" it pays...
|
>> >Thoughts?
>>
>> The taste change sounds more like you were violating another one of
>> Staub's rule (this one I'm fairly sure about, since it accords with my
>> experience). That is, don't reduce the Met during the roast,
>
> That makes no sense Jim.
> How do you reduce an already achieved _maximum_ during the roast?
> Surely you meant just ET?
>
>
It does make sense...
MET is Maximum Environmental Tempreature
How do you achieve this - you still get your MET then you (well probably in
advance) you kill the flame and let it drop...
That or I mis-misunderstood something
Brent
|
| | | | |
Date: 19 Jun 2006 20:06:01
From: Johnny
Subject: Re: Get "MET" it pays...
|
"Brent" <me@privacy.net > wrote in message
news:4fp1snF1kdrp6U1@individual.net...
> >> >Thoughts?
> >>
> >> The taste change sounds more like you were violating another one of
> >> Staub's rule (this one I'm fairly sure about, since it accords with my
> >> experience). That is, don't reduce the Met during the roast,
> >
> > That makes no sense Jim.
> > How do you reduce an already achieved _maximum_ during the roast?
> > Surely you meant just ET?
> >
> >
>
> It does make sense...
>
> MET is Maximum Environmental Tempreature
>
and that is it the MAXIMUM
> How do you achieve this - you still get your MET then you (well probably
in
> advance) you kill the flame and let it drop...
>
> That or I mis-misunderstood something
>
> Brent
>
to the latter: yes.
But the temps that come after MET aren't the MET , it's just the one
point, the maximum. After that it's just ET, Environmental Temperature.
Here's the thing, lets say your MET is 517.375F and you reach it. Anything
after that and less is no longer the MAXIMUM so you can't reduce the MAXIMUM
after it has passed by. Once you reach your maximum that's it. If you then
go down to 405F the maximum is still 517.375F.
|
| | |
Date: 20 Jun 2006 13:41:53
From:
Subject: Re: Get "MET" it pays...
|
In alt.coffee, jim schulman <jim_schulman@ameritech.net > wrote:
> On 19 Jun 2006 08:43:57 -0700, "TimEggers" <timeggers@hotmail.com>
> wrote:
> >Thoughts?
> The taste change sounds more like you were violating another one of
> Staub's rule (this one I'm fairly sure about, since it accords with my
> experience). That is, don't reduce the Met during the roast, otherwise
> the flavor compunds polymerize, and the flavor goes flat.
That's interesting.
In a typical air roaster, ISTM that the input air temp lowers as the beans
become less dense. At first, the beans are heavy and barely move, so the
air flow is slow, and the temp of the air is high. But after drying, and
especially after first crack, the beans are light and loft greatly. So
the air is moving faster, picking up less heat from the coils, with the
result of a lower temperature.
I have a speed control hooked up to my fan, and I often lower the fan
speed as the beans get lighter, to keep the bean movement (and therefore
the input air temp) about the same throughout the roast.
Does this make any sense to you, Jim?
--
A nation of sheep will beget a government of wolves.
--Edward R. Murrow
|
| | | |
Date: 20 Jun 2006 15:23:51
From: jim schulman
Subject: Re: Get "MET" it pays...
|
On Tue, 20 Jun 2006 13:41:53 +0000 (UTC), EskWIRED@spamblock.panix.com
wrote:
>I have a speed control hooked up to my fan, and I often lower the fan
>speed as the beans get lighter, to keep the bean movement (and therefore
>the input air temp) about the same throughout the roast.
>
>Does this make any sense to you, Jim?
Sure does. A popper or uncontrolled airroaster will blow hotter at the
start than the end of the roast, but it's still has to be blowing at
480F+ at the end so as not to stall the roast.
The Hearthware roasters are an exception, since they cycle the fan up
and down in response to a thermostat set where the air enters the
roast chamber. This worked well on the precision, but may have
problems on the i-roast, since the low setting doesn't move the beans
enough at full load.
If you PID an air roaster for bean temp, the inlet air will tend to
over-respond to slope changes in the programmed bean temperature
profile. It will climb rapidly, than fall, in response to the slope
getting steeper; and fall rapidly, then rise, in response to the slope
getting shallower. There will be subsequent cycles depending on how
the actual PID parameters are set. I would suppose this to be more
extreme on a drum roaster controlled for bean temperaturer, since the
thermal lag is longer.
Large commercial convection roasters have proprietary profiles, but
they are all of the same rough shape -- the inlet air temperature is
controlled with a flat or shallow profile at 300F to 375F for a few
minutes, then a sharp rise to 475F to 500F in a few minutes, then
steady there to the end of the roast. I find this to be a good way of
controlling airroasts too; and I use the bean temperature only to end
the roast and fine tune the settings, rather than for direct control.
The explanation of the agtron roast system seems to indicate a
similar three segment heating profile. I'm guessing that the PID is
using an environmental temp to control the flame, but that it's ramp
soak program is being advanced from segment to segment based on
threshold bean temperatures. This is kind of sweet, unfortunately for
us amateurs, the low end PIDs cannot do this with their alarm inputs.
|
| |
Date: 20 Jun 2006 06:59:03
From:
Subject: Re: Get "MET" it pays...
|
Johnny wrote:
> "Erik Groomer" <ViridianCoffee@gmail.com> wrote in message
> news:1150767594.451931.166930@r2g2000cwb.googlegroups.com...
> >
> > Johnny wrote:
> >
<snip / >
> Perhaps it is that the BRR is a stage in the process, whereas MET would
> seem to be an end point ET.
> You could do 401-424 on the way there.
Pretty much...
Hi All...
I felt like it was time to de-lurk and help shed some light on the
Agtron process. I've been to Carl's class and roasted on a 30lb San
Franciscan using an Agtron PID system for a couple of years, and also
kept some time/temp log info during that time - not that I kept any of
it, of course. I don't recall ever being asked to keep anything
confidential, so here's the deal as *I've* found it to be - when I've
questioned Carl on the matter, he was adamant that it was more complex
- and it might possible be... it just didn't seem that way to me.
There's a few more calculations involved - in determining the charge
weight for a particular bean, and determining the crossover (Transition
temp - TT - see below) between stages 2 and 3 below - based on bean
density (for TT) and burner efficiency (for charge weight) due to
variable atmospheric conditions, but I'll leave that out as being a
little beyond the scope of home-roasting.
The roast is essentially broken into 3 (really 2) phases - 1. the drop
(early roast), 2. BRR set point, 3. MET set point. Note that there is
another temp variable in here - the Transition Temp (TT) - which is
calculated from bean density, and is generally in the range 275 =B110 F
- which is measured from *bean* temp, and seems to provide the point at
which the system flips between it's two control states. (Carl states
that it's not a simple control state and that the ET control temp is
ramped up rather than being a set point control.)
Initial conditions: ET =3D MET
1=2E (t =3D 0 - ~2.5 mins) The beans are dropped and the ET begins to drop.
The burners are pretty much full on while the ET begins to drop, until
the mystical TT is reached at which point the control temp flips from
MET to BRR, and the burners go off until ET has dropped below BRR. The
time this takes is presumably dependent on the thermal mass of the
system.
2=2E (t =3D ~2.5 - ~9 mins(from memory)) At this point the burners begin to
cycle again while the system seems to try to control the ET at BRR
temp. In reality, the ET ramps up to the BRR, achieving a steady
ET=3DBRR state at around 6 or 7 (maybe 8) minutes. This continues until
*bean* temp reaches TT, and the control temp flips back up to MET temp.
3=2E (t =3D ~9 - drop) Again, ET and Bean Temp ramp up while the system
tries to raise the ET again. ET =3D MET is achieved again at around 13
or so minutes, and stays steady while bean temp continues to ramp up
towards drop temp.
Those times are completely from memory - I haven't roasted commercially
for a while - so don't take them as absolutes. I just wanted to give a
better overall impression of the way the system works and how BRR and
MET relate to the Agtron roast process.
My take is that the BRR control point is conducive to caramelization
reactions (Maillards ?) and minimization of Trigonellic acid, while the
MET control point kicks in around the time (or slightly before) the
beans start exotherming due to sugar polymerization reactions, which
keeps more short(er)-chain sugars, which are presumably desirable.
As an aside, I think Carl has done a lot of useful work, and
whether/how he chooses to disseminate his findings is up to him. I
don't think he's FoS, as suggested by another poster.
Hope that helps.
Lin.
|
| | |
Date: 20 Jun 2006 08:31:07
From: Ken Fox
Subject: Re: Get "MET" it pays...
|
Thanks for your explanation.
This is obviously a very complicated topic. Most of those posting on this
thread are home roasters using a lot of different types of "roasters,"
everything (literally) from a dog dish with a handheld heatgun to a small
home air roaster to a barbecue grill with a fabricated drum. Temperature
measurements are taken in widely different locations with varying types of
measurement devices.
My opinion is that most will find the following information interesting but
not really usable in their day to day roasting, where I think they would be
better off following a few basic rules (such as not letting temperatures
stay flat or fall during the roasting process) and taking note of when
audible signs of progress (e.g. the cracks) begin and end. Heat input can
be varied in order to attain roast levels within X period of time. Tasting
should be the ultimate arbiter and what works best can be repeated and made
standard. Of course, this is how it has always been done and for the home
roaster I don't think most will be able to use the terminology given below
in a way that will improve their roasting. But, I could be wrong:-)
ken
<nzlinus@gmail.com > wrote in message
news:1150811943.057199.82350@u72g2000cwu.googlegroups.com...
Johnny wrote:
> "Erik Groomer" <ViridianCoffee@gmail.com> wrote in message
> news:1150767594.451931.166930@r2g2000cwb.googlegroups.com...
> >
> > Johnny wrote:
> >
<snip / >
> Perhaps it is that the BRR is a stage in the process, whereas MET would
> seem to be an end point ET.
> You could do 401-424 on the way there.
Pretty much...
Hi All...
I felt like it was time to de-lurk and help shed some light on the
Agtron process. I've been to Carl's class and roasted on a 30lb San
Franciscan using an Agtron PID system for a couple of years, and also
kept some time/temp log info during that time - not that I kept any of
it, of course. I don't recall ever being asked to keep anything
confidential, so here's the deal as *I've* found it to be - when I've
questioned Carl on the matter, he was adamant that it was more complex
- and it might possible be... it just didn't seem that way to me.
There's a few more calculations involved - in determining the charge
weight for a particular bean, and determining the crossover (Transition
temp - TT - see below) between stages 2 and 3 below - based on bean
density (for TT) and burner efficiency (for charge weight) due to
variable atmospheric conditions, but I'll leave that out as being a
little beyond the scope of home-roasting.
The roast is essentially broken into 3 (really 2) phases - 1. the drop
(early roast), 2. BRR set point, 3. MET set point. Note that there is
another temp variable in here - the Transition Temp (TT) - which is
calculated from bean density, and is generally in the range 275 ±10 F
- which is measured from *bean* temp, and seems to provide the point at
which the system flips between it's two control states. (Carl states
that it's not a simple control state and that the ET control temp is
ramped up rather than being a set point control.)
Initial conditions: ET = MET
1. (t = 0 - ~2.5 mins) The beans are dropped and the ET begins to drop.
The burners are pretty much full on while the ET begins to drop, until
the mystical TT is reached at which point the control temp flips from
MET to BRR, and the burners go off until ET has dropped below BRR. The
time this takes is presumably dependent on the thermal mass of the
system.
2. (t = ~2.5 - ~9 mins(from memory)) At this point the burners begin to
cycle again while the system seems to try to control the ET at BRR
temp. In reality, the ET ramps up to the BRR, achieving a steady
ET=BRR state at around 6 or 7 (maybe 8) minutes. This continues until
*bean* temp reaches TT, and the control temp flips back up to MET temp.
3. (t = ~9 - drop) Again, ET and Bean Temp ramp up while the system
tries to raise the ET again. ET = MET is achieved again at around 13
or so minutes, and stays steady while bean temp continues to ramp up
towards drop temp.
Those times are completely from memory - I haven't roasted commercially
for a while - so don't take them as absolutes. I just wanted to give a
better overall impression of the way the system works and how BRR and
MET relate to the Agtron roast process.
My take is that the BRR control point is conducive to caramelization
reactions (Maillards ?) and minimization of Trigonellic acid, while the
MET control point kicks in around the time (or slightly before) the
beans start exotherming due to sugar polymerization reactions, which
keeps more short(er)-chain sugars, which are presumably desirable.
As an aside, I think Carl has done a lot of useful work, and
whether/how he chooses to disseminate his findings is up to him. I
don't think he's FoS, as suggested by another poster.
Hope that helps.
Lin.
|
| | |
Date: 20 Jun 2006 15:25:17
From: jim schulman
Subject: Re: Get "MET" it pays...
|
On 20 Jun 2006 06:59:03 -0700, nzlinus@gmail.com wrote:
>I felt like it was time to de-lurk and help shed some light on the
>Agtron process.
Thanks for the explanation. It sounds like the PID controller uses an
environmental temperature, but that it advances from program step to
program step based on a bean temperature input.
|
| |
Date: 20 Jun 2006 19:54:54
From:
Subject: Re: Get "MET" it pays...
|
Heat + Beans wrote:
> I agree with Ken's post, but need to add a bit of Zennish, soft-focus,
> elaboration.
<snip / >
> So Lin concludes with "Hope that helps." and I have to say, "No, didn't
> help a bit; but some day it might."
LOL... :)
I, too, agree with Ken's post and your own. I'm a long-time popper
roaster - non-modded - so it's pretty useless knowledge when it comes
to *precise* control of a popper roast, though hopefully, the general
roast profile and control details will give others something to try,
and hopefully clarify a couple of points that Tim et al were asking
about.
Cheers,
Lin.
|
| |
Date: 20 Jun 2006 12:27:55
From: Heat + Beans
Subject: Re: Get "MET" it pays...
|
This probably deserves a separate query, but while I'm thinking of it:
We're soon to leave for 3+ wks in Ireland. One week each walking the
Kerry Way and the Wicklow way, with a week in between in Dublin at
meetings. Couple of years ago I had 2 February days at Trinity
College in the damp and gloom of those magnificant buildings. Any
brilliant coffee heads-ups worth going out of my way for?
All of which is also to say that I'll miss LB this year.
Martin
Ken Fox wrote:
> Martin,
>
> hope to see you in LB next month!
>
> ken
|
| | |
Date: 20 Jun 2006 13:46:17
From: Ken Fox
Subject: Re: Get "MET" it pays...
|
Have a good trip, see you in LB at the SCAA or Homecoming in 2007!
ken
"Heat + Beans" <heatgunroast@gmail.com > wrote in message
news:1150831675.630378.136300@p79g2000cwp.googlegroups.com...
> This probably deserves a separate query, but while I'm thinking of it:
>
> We're soon to leave for 3+ wks in Ireland. One week each walking the
> Kerry Way and the Wicklow way, with a week in between in Dublin at
> meetings. Couple of years ago I had 2 February days at Trinity
> College in the damp and gloom of those magnificant buildings. Any
> brilliant coffee heads-ups worth going out of my way for?
>
> All of which is also to say that I'll miss LB this year.
>
> Martin
>
>
>
>
>
> Ken Fox wrote:
>> Martin,
>>
>> hope to see you in LB next month!
>>
>> ken
>
|
| |
Date: 20 Jun 2006 10:16:44
From: Heat + Beans
Subject: Re: Get "MET" it pays...
|
I agree with Ken's post, but need to add a bit of Zennish, soft-focus,
elaboration.
For the begining homeroaster, that "ultimate arbiter" of taste is every
bit as loosey-goosey a standard as the "correct" resting period or
pounds of tamp. Cupping knowledge (the ability to taste what's there
and know the taste you are tasting?) and the techniques of roasting are
iterative, reflexive, and developmental; in other words, today's BS has
a way of morphing into tomorrow's useful information. I also believe
that cupping knowledge is the weakest link in the quest for good
espresso, and that's why I'm averse to "if-it-feels-good-drink-it"
advice on how to pull shots.
That's also why I was tempted to ask Mr. Eggers :o) for some
background on his formal or informal cupping practices. His detailed
posts, IMO, seemed to be overreaching in his quest for technical
answers that he could apply directly to his shot pulling. This may be
close to Ken's point about Lin's post below.
Finally,although I do confine my roasting parameters to the basics, my
basics are richly informed by the work of the Schulmans, Staubs, and
others, even if I can't speak confidently or even correctly about
particular reactions taking place at any moment. By comparison, I
think my superficial knowledge of music theory contributes to my guitar
playing experience even though I can't parse out how (or if) it makes
my music better; my knowledge of psychology helped me better negotiate
my parenting even though I can't say it made me a wiser dad, and the
list goes on.
So Lin concludes with "Hope that helps." and I have to say, "No, didn't
help a bit; but some day it might."
Martin
Ken Fox wrote:
> Thanks for your explanation.
>
> This is obviously a very complicated topic. Most of those posting on this
> thread are home roasters using a lot of different types of "roasters,"
> everything (literally) from a dog dish with a handheld heatgun to a small
> home air roaster to a barbecue grill with a fabricated drum. Temperature
> measurements are taken in widely different locations with varying types of
> measurement devices.
>
> My opinion is that most will find the following information interesting b=
ut
> not really usable in their day to day roasting, where I think they would =
be
> better off following a few basic rules (such as not letting temperatures
> stay flat or fall during the roasting process) and taking note of when
> audible signs of progress (e.g. the cracks) begin and end. Heat input can
> be varied in order to attain roast levels within X period of time. Tasti=
ng
> should be the ultimate arbiter and what works best can be repeated and ma=
de
> standard. Of course, this is how it has always been done and for the home
> roaster I don't think most will be able to use the terminology given below
> in a way that will improve their roasting. But, I could be wrong:-)
>
> ken
>
>
> <nzlinus@gmail.com> wrote in message
> news:1150811943.057199.82350@u72g2000cwu.googlegroups.com...
> Johnny wrote:
> > "Erik Groomer" <ViridianCoffee@gmail.com> wrote in message
> > news:1150767594.451931.166930@r2g2000cwb.googlegroups.com...
> > >
> > > Johnny wrote:
> > >
> <snip />
> > Perhaps it is that the BRR is a stage in the process, whereas MET would
> > seem to be an end point ET.
> > You could do 401-424 on the way there.
>
> Pretty much...
>
> Hi All...
>
> I felt like it was time to de-lurk and help shed some light on the
> Agtron process. I've been to Carl's class and roasted on a 30lb San
> Franciscan using an Agtron PID system for a couple of years, and also
> kept some time/temp log info during that time - not that I kept any of
> it, of course. I don't recall ever being asked to keep anything
> confidential, so here's the deal as *I've* found it to be - when I've
> questioned Carl on the matter, he was adamant that it was more complex
> - and it might possible be... it just didn't seem that way to me.
> There's a few more calculations involved - in determining the charge
> weight for a particular bean, and determining the crossover (Transition
> temp - TT - see below) between stages 2 and 3 below - based on bean
> density (for TT) and burner efficiency (for charge weight) due to
> variable atmospheric conditions, but I'll leave that out as being a
> little beyond the scope of home-roasting.
>
> The roast is essentially broken into 3 (really 2) phases - 1. the drop
> (early roast), 2. BRR set point, 3. MET set point. Note that there is
> another temp variable in here - the Transition Temp (TT) - which is
> calculated from bean density, and is generally in the range 275 =B110 F
> - which is measured from *bean* temp, and seems to provide the point at
> which the system flips between it's two control states. (Carl states
> that it's not a simple control state and that the ET control temp is
> ramped up rather than being a set point control.)
>
> Initial conditions: ET =3D MET
>
> 1. (t =3D 0 - ~2.5 mins) The beans are dropped and the ET begins to drop.
> The burners are pretty much full on while the ET begins to drop, until
> the mystical TT is reached at which point the control temp flips from
> MET to BRR, and the burners go off until ET has dropped below BRR. The
> time this takes is presumably dependent on the thermal mass of the
> system.
>
> 2. (t =3D ~2.5 - ~9 mins(from memory)) At this point the burners begin to
> cycle again while the system seems to try to control the ET at BRR
> temp. In reality, the ET ramps up to the BRR, achieving a steady
> ET=3DBRR state at around 6 or 7 (maybe 8) minutes. This continues until
> *bean* temp reaches TT, and the control temp flips back up to MET temp.
>
> 3. (t =3D ~9 - drop) Again, ET and Bean Temp ramp up while the system
> tries to raise the ET again. ET =3D MET is achieved again at around 13
> or so minutes, and stays steady while bean temp continues to ramp up
> towards drop temp.
>
> Those times are completely from memory - I haven't roasted commercially
> for a while - so don't take them as absolutes. I just wanted to give a
> better overall impression of the way the system works and how BRR and
> MET relate to the Agtron roast process.
>
> My take is that the BRR control point is conducive to caramelization
> reactions (Maillards ?) and minimization of Trigonellic acid, while the
> MET control point kicks in around the time (or slightly before) the
> beans start exotherming due to sugar polymerization reactions, which
> keeps more short(er)-chain sugars, which are presumably desirable.
>
> As an aside, I think Carl has done a lot of useful work, and
> whether/how he chooses to disseminate his findings is up to him. I
> don't think he's FoS, as suggested by another poster.
>=20
> Hope that helps.
> Lin.
|
| | |
Date: 20 Jun 2006 11:41:15
From: Ken Fox
Subject: Re: Get "MET" it pays...
|
Martin,
hope to see you in LB next month!
ken
|
| |
Date: 21 Jun 2006 05:24:04
From: Omniryx@gmail.com
Subject: Re: Get "MET" it pays...
|
Wise words, br'er Fox.
Will
Ken Fox wrote:
> My opinion is that most will find the following information interesting but
> not really usable in their day to day roasting, where I think they would be
> better off following a few basic rules (such as not letting temperatures
> stay flat or fall during the roasting process) and taking note of when
> audible signs of progress (e.g. the cracks) begin and end. Heat input can
> be varied in order to attain roast levels within X period of time. Tasting
> should be the ultimate arbiter and what works best can be repeated and made
> standard. Of course, this is how it has always been done and for the home
> roaster I don't think most will be able to use the terminology given below
> in a way that will improve their roasting. But, I could be wrong:-)
|
|
