HomeRoast Digest


Topic: Astringent Yirg -- Where did I go wrong? (10 msgs / 244 lines)
1) From: Randall Nortman
Of all the beans I have roasted so far, the late harvest Yirgacheffe
from SM (no longer in stock) has been my favorite.  But this morning I
tried my most recent batch, roasted a couple of days ago, and the
citrusy brightness I remember had given way to a tea-like astringent
quality that I did not particularly care for.  The beans have not
changed.  The grinding and brewing has not changed.  Must be the
roast.
I roast in a modified Poppery I with the heater on a dimmer.
Unfortunately, I can't directly compare this roast to previous ones,
as I am using a different temperature probe setup -- I like the new
setup much better.  It gives more precise and repeatable results, so
in the future I will be much more able to repeat, tweak, and compare
roasts.  But alas, I can't really make a good comparison to those
first roasts of this bean that I liked so much.  If I had to guess,
I'd say I roasted this batch just slightly darker than the previous
ones.  I have also added a drying phase at the beginning of the roast,
where I ramp the bean mass from 200F to 300F over the course of about
3-4 minutes, and then sprint from there to first crack at full power,
and then I back off and proceed slowly to the end of the roast.  In
this case, that was at about 440F after 10-11 minutes total roast
time.  (I know, I *really* need to log this stuff.)  I can't say with
certainty what the previous final temps were, but probably in the
435-440F range.
Any ideas on what went wrong, and what I should do differently next
time?  Alas, this was the very last of that batch, but I have some of
the current stock of Oromia Yirg headed my way.  (Actually, it should
have been here already -- Harvey is dragging his feet.)

2) From: Michael Dhabolt
Randall,
Randall Nortman wrote:
<Snip>
Do you "proceed slowly to the end of the roast" starting at the beginning of
first crack or the end?  Starting the slow ramp to EOR at the beginning of
1st rather than the end of 1st, has made a substantial difference in my
roasts.
Mike (just plain)

3) From: miKe mcKoffee
This is a multi-part message in MIME format.
Agree with Mike (just plain). If by "astringent" you mean a tightening
sensation in the back of the throat agree a mellower profile, especially
just approaching start of 1st to end of roast, can tame it. Also may not
want to go "too" fast after tanning up to start of first, just fast enough
for even color change. First learned about and how to tame a rather wild
astringent coffee during a multi-Lister roast exchange of Kenya Mika a few
years back. Night & day difference between a 12 and 15 minute roast with 1
minute extra after drying stage leading up to first and 2 minutes longer
start of 1st to end of roast. All the great Kenya Mika varietal character
remained without any astringency. FWIW that was taking it about FC both
profiles.
 
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately 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 Michael Dhabolt
Sent: Saturday, May 05, 2007 10:32 AM
To: homeroast
Subject: Re: +Astringent Yirg -- Where did I go wrong?
Randall,
Randall Nortman wrote: 
I ramp the bean mass from 200F to 300F over the course of about
3-4 minutes, and then sprint from there to first crack at full power, 
and then I back off and proceed slowly to the end of the roast.
Do you "proceed slowly to the end of the roast" starting at the beginning of
first crack or the end?  Starting the slow ramp to EOR at the beginning of
1st rather than the end of 1st, has made a substantial difference in my
roasts. 
 
Mike (just plain)

4) From: Randall Nortman
I would describe it as a tightening or dryness on the tongue and roof
of mouth more than in the back of the throat.  This is effect you get
from tannins in tea or a very tannic red wine.
I have been slowing it down as soon as I get the first pops of first
crack, but my version of slowing it down is to bring the temperature
to 420-430F and hold it steady or very slowly rising until first crack
is completely done and I'm ready to head for whatever my final
temperature will be, or else I just end it right there for a light
roast.  Perhaps I need to slow it down as soon as I hit 400F?
(Remember, this is hot air roasting, probe in the bean mass.)
On Sat, May 05, 2007 at 12:44:53PM -0700, miKe mcKoffee wrote:
<Snip>

5) From: miKe mcKoffee
400f is where I hit the ramp brakes, also probe in bean mass Rosto hot air
roasting, with anticipated start of 1st any time now up to ~410f depending
on the bean. I never actually hold the temp during first, but been going for
about 3 minutes 400f to 430f then pick up the ramp for additional 1 to 3 min
to end of roast temp depending on bean/degree of roast.
It may have just been a tad lighter roasted than you'd like too!
Pacific Northwest Gathering Vhttp://home.comcast.net/~mckona/PNWGV.htmKona Konnaisseur miKe mcKoffee
URL to Rosto mods, FrankenFormer, some recipes etc:http://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately 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>

6) From: Michael Dhabolt
Randall,
Randall Nortman wrote:
<Snip>
Yes, I understand.  My roaster (P1) is PID controlled, so to circumvent a
rapid temperature transient at ramp change-over that would push me above
400, I start slowing down (an extra ramp) at approx 385.  I theorize that
being fully 'into' a slower heat-up rate when 1st starts is beneficial.  I
also try to manipulate the fan speed / bean circulation during this period
slowly, so as not to present the beans with the dreaded temperature
transients.
miKe's comments regarding the 300 to 400 heat-up and the overall length of
roast to tame the astringency, are in line with my thinking and practices.
Mike (just plain)

7) From: Ed Needham
Yirg is one of those beans that has an extremely narrow window of 
opportunity for the perfect roast.  Too light and it is astringent like 
green grass, too long and it is muddy, lifeless and nothing special at all. 
Hit it right and it will have a bit of lemon rind in the finish balanced 
with the most wonderful chocolate/coffee flavor.  The nutty aroma rocks my 
boat too.
*********************
Ed Needham®
"to absurdity and beyond!"http://www.homeroaster.com(include [FRIEND] in subject line to get through my SPAM filters)
*********************

8) From: Ken Mary
<Snip>
My drum roaster needs to be turned down starting at 355 to 375 F bean
temperature. Of course this is due to my drum's slower thermal response. I
always tried for a fully linear ramp going into first crack (395F). Whether
or not this is required is open for debate. But to me it is useful to
achieve my desired finish temperature at the correct time after first.
--

9) From: Ken Mary
<Snip>
You can compare the bean expansion and weight loss with previous roasts of
the same lot of coffee. You need a cylindrical container at least twice the
volume of the green coffee. Record the height of the green and roasted fill,
the ratio of the height is the expansion. Expansion is dependent on several
variables, but it is useful when comparing different profile times to the
same finish temperature or different finishes with the same profile time.
Weight loss is similarly easy to measure, but you will need a scale
measuring to 0.1 gram with the Poppery size load. Weight loss is not very
useful when comparing different coffees or even different lots of the same
coffee due to moisture and chaff.
--

10) From: Wes Tyler
Ken..are there pictures of your roaster posted anywhere? I'm interested in a drum, but don't have room for a dedicated grill.
 Wes
----- Original Message ----
From: Ken Mary 
To: homeroast
Sent: Sunday, May 6, 2007 8:15:28 AM
Subject: Re: +Astringent Yirg -- Where did I go wrong?
<Snip>
My drum roaster needs to be turned down starting at 355 to 375 F bean
temperature. Of course this is due to my drum's slower thermal response. I
always tried for a fully linear ramp going into first crack (395F). Whether
or not this is required is open for debate. But to me it is useful to
achieve my desired finish temperature at the correct time after first.
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