HomeRoast Digest


Topic: To H2O or not To H2O (30 msgs / 815 lines)
1) From: Tom Gramila
Hello again all,
	I have just brewed up my water treated roast, the one described in
the "speculations gratefully accepted" thread.  I will temper these
comments by remarking that this is not a blind comparison -- the
differences are based, so far, on todays cup compared to recent
non-water-treated roastings.
	So first prize in the predictions tally goes to: 
  Jim Schulman, who said: "My take on it is that it will shorten the roast
time required to get to the same taste (more water, faster chemistry). But
I'm not sure what it'll do for the same roast time - perhaps the flavors
will be more intense"
		and  a close first runner up to
  Johnny Kent who said: " My speculation is (given that you are using
regular greens, not old dried out ones, and not knowing how you store your
greens) that: 1. the quality of the cup will improve (just a guess! no
rationale)"
	What tipped the scales to Jim was the use of the word "intense".  
Intense is indeed the best descriptor of this cup.  It is big, chewey,
full, and leathery.  It has a strong lingering aftertaste.  The aroma is
marginally improved.  It is markedly different than the 4 or 5 roastings
that I have done of this harrar in the past 6 weeks.  My wife, who is less
likely to be biased, agrees.  OK, so this is not a blind tasting, but I
hope to do that wednesday or friday.
	Now its my turn to speculate.  I wonder why this has made such a
difference.  I use an air roaster -- perhaps that approach is much more
sensitive to humidity levels, I've heard that drum roasting sets up a
micro-environment. Clearly air roasting blasts this out of the roaster.
And I roast outdoors, the dewpoint was below 20F.  I keep the beans in the
zip lock bags that Tom ships them in, I dont know how the bean moisture
content varies with season.  I wonder whether this might have a much
smaller effect in much humid environments, or in drum roasters.  In any
case I am going to keep trying this out....
-- 
				Tom G.
Proof of Principle Computer Controlled Poppery Coffee Roasterhttp://home.columbus.rr.com/thegramilas/coffee/roaster.html

2) From: Gene Smith
<Snip>
I have wondered about this ever since I first heard about air roasting.  It
seems, intuitively, that there must be a difference between blowing lots of
hot air over the beans and heating them in a more restricted vessel.  I
don't pretend to know whether there is enough of a difference to make a
difference.  Again guessing, it would seem that the difference would affect
the lighter aromatic compounds the most.
Any thoughts from the more experienced roasters?  At the very least, it
would seem that one would want to minimise the airflow - which is to say,
not use more than what is necessary to just move the beans sufficiently for
even roasting.  Does this sound right?
Gene Smith
riding the wild learning curve in Houston

3) From: miKe mcKoffee
Tom,
Your speculations are the same reason I use very minimal bean movement with
my Rosto roasting. Just a slow ocean wave like movement, never *racing*
except for cooling. It improved the quality of my roasts IMO. I don't use
increased fan speed to slow a profile, I decrease heater.
Kona Konnaisseur miKe mcKoffee
MCSE (Maniacal Coffee Systems Engineer/Enthusiast;-)
URL to Rosto mods, FrankenFormer etc.http://mdmint.home.comcast.net/coffee/Rosto_mod.htm

4) From: miKe mcKoffee

5) From: Oaxaca Charlie
 Mike, your carefully controlled air roasts convinced me that
one doesn't need a drum roaster to get a "drum roasted" taste.
Quite a few pro drum roasters go for very fast (8 minute) roasts
and sell coffee that tastes just like the pro air roasters with
their 8 minute (or less) roasts.  Your coffee's full
flavor,complexity, body, and every other important ingredient
are all the proof I need that air roasting can do it all, when
done right.
  Charlie
--- miKe mcKoffee  wrote:
<Snip>http://www.sweetmarias.com/maillistinfo.html=====
Brick Oven Roasting in British Columbia
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6) From: Jim Schulman
On 22 Dec 2003 at 10:55, Gene Smith wrote:
<Snip>
This is certainly the conventional wisdom, but I'm not buying it 
without proof. 
1. The interior of the bean is at about 12 atmospheres pressure 
through most of the roast. How much difference to outgassing can 
the flow of the an airroaster make, given such a huge pressure 
gradient? It's as silly as saying a diver's watch will start 
leaking if you blow on it.
2. Illy tried roasting in pure nitrogen and even pressurized 
nitrogen atmospheres and discovered no difference in taste.
Jim

7) From: Gene Smith
Jim writes:
<Snip>
That is very interesting, and makes sense, Jim.  Clearly, the air blast
would significantly increase outgassing from the bean.  On the other hand,
it still seems possible that greatly increased airflow could influence the
chemistry occurring on the surface of the bean during roasting.
Drying occurs faster with heat and airflow than with either by themselves
(unless we are speaking of metal-melting temperatures or cyclonic
winds)...wouldn't faster drying of the bean surface during roasting affect
the chemical happenings there?
Since the general opinion around here seems to be that air and drum roasts
are detectably different...what would cause that difference?
<Snip>
My next question would be: Did they just roast in a nitrogen atmosphere, or
did they roast with a blast of heated nitrogen?  As we are all already
roasting in a gas (air) that is mostly nitrogen, it seems to me that
roasting in pure nitrogen would suggest more about the effect of oxygen on
roasting than airflow.
Gene Smith
riding the wild learning curve in Houston

8) From: Johnny Kent
That's interesting Jim.
Can you give us a reference to the 12 atmospheres pressure.
I'd like to read more about that.
Thanks,
Johnny
At 04:30 PM 12/22/2003 -0600, you wrote:
<Snip>http://www.sweetmarias.com/maillistinfo.html<Snip>

9) From: Johnny Kent
At 10:07 PM 12/22/2003 -0600, Gene wrote:
<Snip>
It's not clear to me that this is what is happening since we aren't talking
about applying them independently. The application of the heat in air
roasting is through conduction with the air flowing over the beans. It's
hard to separate the the heat from the air flow.
How much heat is transferred to the beans is a function of both the air
temp and the flow rate.
To my thinking the chemistry is more dependant on the temperature gradient
within the bean and this comes from how fast the surface is heated.
<Snip>
One thing that may cause a difference is that with drum roasting there is
point contact of the bean with the drum and this will cause heat to flow
into small areas on the bean whereas with air roast the heat from the air
envelopes the bean and the heat tranfer is evenly distributed.
<Snip>
That's what I'd like to know also.
 Any more info on that Jim?
Respectfully, 
Johnny

10) From: David Lewis
At 10:55 AM -0600 12/22/03, Gene Smith wrote:
<Snip>
That was indeed one of the conclusions of a paper on hot air roasting 
done for a Swiss doctoral thesis a year or so ago. (Check the list 
archives or search alt.coffee for the paper.) Unfortunately, the 
author made no attempt to profile the roast, so it may or may not be 
germane to real roasting.
Best,
	David
-- 
"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

11) From: Johnny Kent
At 11:42 AM 12/22/2003 -0500, TomG wrote:
<Snip>
So my speculation, is that what's happening is that you are getting a
slightly darker and more even roast over a slightly longer time and so the
flavors are more developed. Why?
Same reasoning as why 1st crack was at a lower temp: the extra water causes
the heat to be applied longer to get rid of that initial water, before the
chemistry that causes first crack starts. When that's done the internal
bean temp is higher, due to a longer heat application. At that point there
is a lower than usual temperature differential between the surface and the
center. Once this lower than usual temp differential is set it carries on
some throughout the roast. Your controller terminates the roast based on
reaching a preset surface temp. When the preset is reached the internal
bean temp is higher than usual, hence a little darker, due to the lowered
temp differential. Also the temp gradient through the bean is lower than
normal giving a more even roast.
FWIW, it seems to me that a similar result might be achieved by slowing the
rate from first crack onwards.
Johnny

12) From: Jim Schulman
On 22 Dec 2003 at 21:13, Johnny Kent wrote:
<Snip>
There was a reference in the roasting dissertation, but I 
couldn't hunt it down. All I could find is that the gases in the 
cooled, fully roasted bean are between 5 and 8 bar prior to 
outgassing.
Jim

13) From: Jim Schulman
On 22 Dec 2003 at 22:07, Gene Smith wrote:
<Snip>
A few days back I posted a half-facetious question about being 
able to grind the surface of beans separately from the interior. 
The reason I asked is because I'm starting to think a lot of 
roast quality differences may be confined to the surface of the 
bean.
Jim

14) From: Jim Schulman
On 22 Dec 2003 at 22:07, Gene Smith wrote:
<Snip>
A few days back I posted a half-facetious question about being
able to grind the surface of beans separately from the interior.
The reason I asked is because I'm starting to think a lot of
roast quality differences may be confined to the surface of the
bean.
Jim

15) From: Tom Gramila
Johnny,
	A bunch of interesting conjectures.  I've embedded comments 
below:
On Mon, 22 Dec 2003, Johnny Kent wrote:
<Snip>
	This roast reaches exactly the same outer bean measured
temperature, in, I think, the same airflow(which may influence the
measurement), so I'm not sure that I am roasting "darker".  The time of
the roast was also very close -- I will check this more carefully when I
roast both wet and dry in sequence.  However, if, by more even, you mean a
more uniform temperature through the bean, that is certainly possible --
and I agrees that this could provide a more intense cup.
<Snip>
	First: Hooray!!!, Second, why indeed....
<Snip>
	OK - two points.  The only place where the roast can be "longer"  
is in the stage up to 225 degrees.  After that, the remaining ten minutes
or so is repeatable to within a handful of seconds, roast to roast, with
different beans, in different seasons.  This is because I regulate on
measured bean temperature.  If perhaps you mean that the water leaves 
later in the roast, then I need to rethink my comments.
	Assuming that it takes longer in this early stage: I think that
any difference would tend to be mitigated in my roasting because the
profile includes a 30 second hold at 225 degrees external bean
temperature, and one can see the heater power decrease and level out
during this time.  I have understood this to be caused by a reduction in
the heat needed to get the inside of the bean to equilibrium.  So I think
that at this stage, the beans are pretty uniform in temperature, both
"wet" and dry.
<Snip>
	OK - I think I agree with a fundamental point here.  I had been
thinking that the presence of additional water vapor in the beans would
influence the chemical pathways "chosen". This has been established, and
brought to my attention by members of this list, including Jim Schulman
and others whom I can't remember.  I thought the quote was from Sivetz.
(sp?)  However, you are asserting another influence, which is, that the
presence of the extra water influences the temperature difference between
the inside and the outside of the bean.  You have indicated this in terms
of times, but I think that the water could likely significantly affect the
beans thermal conductivity.  In any case, your recognition that a higher
internal temperature would affect the development of flavors during the
roast due to potentially higher internal temperatures seems to me to be on
the mark.
<Snip>
	Interesting correlation there.  I would think that there are three
possible influences of water that could lead to a lower first crack
temperature.  First is an additional pressure that arises due to the water
vapor's presence.  Second would be the possibility that its presence has
altered chemistry enough that there is more CO2 in the bean.  Third, as
you have suggested, the bean internal temperature is closer to the
outside, so the external temperature for first crack to occur ends up
"appearing" lower.
	I would have to say that all of these are plausable, and that
there are varying pieces of evidence related to each.  First, the
observation that the final weights are the same (wet/dry starts) would
seem to suggest that the water is GONE by the end of the roast, I would
guess that it may be mostly gone by first crack too, but it would perhaps
be hard to tell.  This could perhaps be measurable, but I would be
reluctant without a better scale.  Second, the noticable difference in
flavor ( assuming it is real and stands up to blind and repeat cuppings)  
would seem to say that the chemistry has been altered.  Finally, I have
never been able to detect a difference in color between the inside and the
outside of my roasted beans (at least lately), so I dont know how to
evaluate a more uniform internal bean temperature.
<Snip>
	I think that too many other things happen as well, so lengthening 
the roast after first is not equivalent. I have tried it, and it really 
flattens out the taste, rather than enchancing the intensity.
	Thanks much for the comments/thoughts, this stuff is sure puzzling
to me!
				Tom G.
Proof of Principle Computer Controlled Poppery Coffee Roasterhttp://home.columbus.rr.com/thegramilas/coffee/roaster.html

16) From: Tom Gramila
Hi Jim and Gene,
	
On Mon, 22 Dec 2003, Jim Schulman wrote:
<Snip>
	I think that it may be more complicated than the divers watch
analogy.  While I agree that he extra air flow can only make a tiny
difference for the CO2 bean exiting rate, there are lots of components
that are leaving the bean, some of which may have relatively small partial
pressures, for which the air flow could therefore make a difference.  
Unless, of course, all vapors exiting the bean are a homogeneous mix with
the CO2, and are trapped by the same obstructions...
	We know that caffine, for example, leaves the bean (by the
experience of many, and recently stated quotes).  In fact alot of stuff
has to leave the bean -- in my roasts I lose 30 out of 180 grams of mass
-- all of that has to leave the bean as vapor (excepting chaff).
	I think of the bean as more of a barely leaky sponge, a huge
internal pressure builds up, but who is to say whether the distribution of
important components has spatial segragation, or low internal pressures,
etc. If it were a single component system, I think it would be nuts, given
the CO2 internal pressure, to think that air flow will matter.  But boy it
makes me nervous to conclude that it doesnt for this complex a "system"...
<Snip>
	I would think that this would affect oxidation much more than 
"evaporation" of flavor elements.
	Maybe this thread should get renamed: 
  To blow or not to blow -- THAT is the question!
				Tom G.
Proof of Principle Computer Controlled Poppery Coffee Roasterhttp://home.columbus.rr.com/thegramilas/coffee/roaster.html

17) From: Oaxaca Charlie
 What a great recent addition the the Home Roast you are, Tom.
 I'm loving this thread. I'll throw a probably irrelevent
observation in here, just in case. When baking bread in the
brick oven, placing some pans of water in there to steam just
before putting the bread in doesn't change the thermometer
readings, but prevents burning of the crust. One can start the
baking at a higher than usual temporature, even, thus getting a
better "bounce" in the loaves. I've tried doing the same thing
with the pans of water when roasting, but never followed through
with blind cupping, or even carefully measured timing/temp
recordings. I'm "soaking" (same small amount of water you used
with the Harrar) some Yemen beans tonight and if I get full-on
chewy, intense magic instead of soft, over mellow ho-hum (And
I'm talking about Tom's Ismaeli here) I'll be mighty impressed.
 Wish me luck.
  Charlie
--- Tom Gramila  wrote:
<Snip>http://www.sweetmarias.com/maillistinfo.html=====
Brick Oven Roasting in British Columbia
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18) From: Johnny Kent
Good luck!
What roasting apparatus are you using?
Johnny
]At 03:13 PM 12/23/2003 -0800, you wrote:
<Snip>http://www.sweetmarias.com/maillistinfo.html<Snip>

19) From: Oaxaca Charlie
--- Johnny Kent  wrote:
<Snip>
 Me? A RK special edition (extra long) drum, and a wood fired
brick oven with a powered roller assembly to turn the drum.
 Palm frond mat and fan for quick cooling.
  
       Charlie
<Snip>
<Snip>
=== message truncated ===
=====
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20) From: Ed Needham
Great report!  Very interesting.  Maybe there is something to 're-hydrating'
beans before roasting.  I may try it with some older beans I have that are a
bit on the 'not so green and lively' side.  Beats the heck outta tossing
them.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

21) From: miKe mcKoffee

22) From: Tom Gramila
On Tue, 23 Dec 2003, Oaxaca Charlie wrote:
<Snip>
Charlie,
	What a delightful  thing to hear from one of the real experts on 
list.  Thanks! 
<Snip>
	Interesting.  I remember someone mentioning that some commercial 
roasts had steam injection or some such during the roasts.  I wonder what 
the logic of that really is, or if I'm even remembering correctly??
I'm "soaking" (same small amount of water you used
<Snip>
	Good luck! I am going to try again with both wet and dry with a 
blind tasting as soon as I have time...
	Please keep us posted -- I'm really anxious to hear!
				Tom G.
Proof of Principle Computer Controlled Poppery Coffee Roasterhttp://home.columbus.rr.com/thegramilas/coffee/roaster.html

23) From: miKe mcKoffee

24) From: Ed Needham
These were on the dry side when I received them.  I probably only have about
five pounds of beans that are over the hill.  My guess is that vac sealing
them would have been a good thing.  I just 'hate' to get that organized
though .
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************

25) From: miKe mcKoffee

26) From: Ben Gold
I didn't keep the original how to add water e-mail. Could someone tell me how the add H2O is done (was done).
Thanks
Ben2
Tom Gramila  wrote:
On Tue, 23 Dec 2003, Oaxaca Charlie wrote:
<Snip>
Charlie,
What a delightful thing to hear from one of the real experts on 
list. Thanks! 
<Snip>
Interesting. I remember someone mentioning that some commercial 
roasts had steam injection or some such during the roasts. I wonder what 
the logic of that really is, or if I'm even remembering correctly??
I'm "soaking" (same small amount of water you used
<Snip>
Good luck! I am going to try again with both wet and dry with a 
blind tasting as soon as I have time...
Please keep us posted -- I'm really anxious to hear!
Tom G.
Proof of Principle Computer Controlled Poppery Coffee Roasterhttp://home.columbus.rr.com/thegramilas/coffee/roaster.html

27) From: Oaxaca Charlie
--- miKe mcKoffee  wrote:
<Snip>
 I don't think so, Mike. That robusta steaming is pre-roast. The
steam injecters, the way I understood it, were for keeping temps
from running into 3d crack range when roasting large (hundreds
of lbs) roasts. Or profile adjustments on huge batch roasts.
Something like that, anyway... Tom, or would  Barry know.
  Charlie
=====
Brick Oven Roasting in British Columbia
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28) From: Gene Smith
<Snip>
how the add H2O is done (was done).
<Snip>
Dear Ben,
I don't think you can actually add water to e-mail...I'm pretty sure that
it's not allowed as an attachment.
Sorry, the Ho! Ho! Ho! thing just got to me.  There have been hints that
there is something under the tree that makes coffee with a pump instead of
steam...  Have I got the Christmas spirit?  Oh yeah!
Gene Smith
getting pumped for Xmas (he hopes!)

29) From: Peter Barnes
I don't really know anything about this, and I certainly don't know 
right from wrong, but if I remember correctly, Tom had a write-up about 
this process which he described as enabling large roasters to make 
Robusta taste like it came from Brazil and not the lower levels of 
hell.  I believe he was refering to a cup of coffee he had at McDonalds 
while on the road.  Maybe I'll wander through the archives a bit to see 
if I can find that...
cheers
peter
Oaxaca Charlie wrote:
<Snip>

30) From: Ed Needham
I have a large rack in the stairwell going to my basement, which is partially
heated and cooled.  The temps stay below sweltering in the summer and above
freezing in the winter.  It's dark and cool most of the time.  I usually toss
the 5 pound bags into shoebox sized plastic containers I got at Wal-Mart and
store them on the shelves of the rack.  I can easily store about 150 pounds
of greens that way.
I only roast 5 to 10 pounds a week.  Sometimes more if I get a special
request.
I've never received any beans from Sweetmaria's that are anywhere near dry,
but I've gotten some from others when I go out on a lark to find a bean I
have liked in the past.  I got a few pounds of Maui Moka that I 'knew' would
be past it's prime, but I just had to try it.  I'm glad I did, but it was not
as good as what I originally fell in love with when I could get it fresh.  I
did the same thing with Sumatra Blue Lintong.  Tom had it for a while and
then it disappeared.  Another source had it and I got 15 pounds or so, but it
just wasn't the same, so it sat on the shelf for longer than usual.  I've got
a smorgasbord of one pound quantities of beans that are aging on my shelves.
Now that I have my smaller, solid wall drum roaster, I'll probably be pulling
more of these out and roasting them.  They might make good beans to
experiment on with the 're-hydration' scheme.
***********************************************
Ed Needham
To Absurdity and Beyond!
homeroaster ... d.o.t ... com
***********************************************


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