HomeRoast Digest


Topic: A very basic question about acidity and roast profiles (long) (5 msgs / 265 lines)
1) From: Vicki Smith
I'm a roasting newbie, still getting acquainted with my iRoast-2. I've 
noticed that there seems to be a big emphasis from more experienced (and 
knowledgeable) home roasters than I may ever be on prolonging the roast 
time, in particular the time between 1st and 2nd crack, with this roaster.
My understanding (and I may be totally misinformed) is that shorter 
roasts produce (pr mebbe leave behind) more acidity. I also noticed that 
Tom, in his tip sheet 
http://www.sweetmarias.com/hearthware.iRoasttipsheet.html)has a 
suggested roast profile that runs between 9-11 minutes, depending on the 
degree of roast desired as well as a cupping profile that is only 9.5 
minutes.
This tip sheet, btw, is much more detailed than the one that came packed 
with my roaster, ordered about two months ago.
My question is this: If we are purposely buying coffee known and valued 
for its "brightness/acidity" then should we really be looking to prolong 
our roast times in a machine like the iRoast-2? I guess I am wondering 
if we fluid bed roasters are going after that in an attempt to roast 
like the big boys, without really "getting" the difference in our machines.
++++++++++++++++++++++++++++++++++++++++++++
Here are some bits of the tip sheet:
Tom's cupping profile (city, city +)
"Sample Roast Curves for Specific Coffees:
Here's the roast curve that I use for almost all samples to get a City 
or City plus roast (which is considered a cupping roast I know and is 
probably lighter than most folks like):
Total roast time: 9:30 min
     * Stage 1: 350 F for 2:00 min
     * Stage 2: 400 F for 3:00 min
     * Stage 3: 460 F for 4:30 min"
Tom's suggested general roast profile:
"A basic profile I am using is my lower-heat warm up profile. It 
benefits all coffees, and only causes problems with really dense seeds 
that need a higher initial temperature. Basically it is
340 for 2 minutes --this will give you a high speed air pattern to aid 
in really even initial heat distribution
390 or 400 for 3 minutes -- this raises the temperature right to the 
verge of first crack
450 for 4 to 6 minutes -- with most coffees, 4 minutes will give you a 
City Roast, 5 a Full City, and 6 gets you to the door of 2nd crack. "
Vicki (feeling foolish and pretty much convinced that no one will 
understand this muddle headed issue)
!*!*!*!*!*!*!*!**!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*!*
                 Taming Coffee: The Weblog
                 http://taming.motime.com

2) From: miKe mcKoffee
Vicki,
Your musings not foolish or muddled at all IMO. I don't use either I-Roast
but have primarily air roasted with the Rosto, last 4 years or so with dual
variable boost voltage control of heat & fan. I've experimented with total
roast time profiles ranging from super fast FR emulating 5min total time out
to 20min roasts. (not including cooling times) Too slow will flatten the
roast while too fast will be lacking in body and complexity. My profiles now
run from 9 to 15min max, most beans and roasts 10 to 12 min. (Wild Kenyas
and espresso only blends slower profiles.) A 3 to 6 minute start of 1st to
end of roast air roasting seems to be necessary regardless the finish degree
or major risk of grassy undeveloped taste, do to not fully roasting the bean
internally. Most of my City+ to FC profiles run 3:30 to 4:30min start of 1st
to end of roast. (I've also found grassiness can be caused to a lesser
degree by going too fast pre-tanning stage, my up to 300f stage, but with
the I-Roast you have no control of that segment) 
The trick is to get the balance of acidity and body best to your taste for
given bean and brewing method. Best way is to play with different profiles
yourself.
And don't discount or neglect resting your roasts, especially lighter
roasts! Oft bland and boring at even 2 or even 3 days rest expodes with
flavor at 4 days or more...
Hope this helps more than befuddles!-)
Kona 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.
<Snip>

3) From: Michael Wade
Vicki
Everything you've said is pretty much right on target in my experience.
Prolonging or "stretching" the roast will decrease brightness, increase 
body.
After struggling with my iR2 for a while I wound up speaking with Gene in 
customer service at Hearthware, who sent me a sample profile for stretching 
roasts.  I eventually came to the conclusion that: 1. I prefer brighter 
coffees and was going in the wrong direction.  2. I needed to gain 
experience with a simple profile before attempting to branch out. 3. I 
really needed a thermocouple in the roast chamber to satisfy my need for 
repeatable results.
I installed a thermocouple and have been recording my roasts for a while. 
Now I'm not so sure that it matters all that much, but it served to satisfy 
my need for getting control of the process.  Or at least being able to 
monitor the process.  Control remains ever elusive.
On interesting thing that Gene mentioned and experience has borne out is 
that there are undocumented default profiles programmed into the iR2 that 
will override anything you program in.  For example, there is a default 
profile "to dry the beans" according to Gene, that will hold the machine at 
~350F for a period of time no matter what you program in.  I have tried 
programming 320 for 2 minutes, but the machine goes right up to 350, and I 
have programmed 400 for 5 minutes and the machine will climb to ~350  and 
hold there for anywhere from 1:50 to 2:30 until  it satisfies some arbitrary 
condition or other, then allow my program to resume control.
I have also found that no matter what I program in for the first 5 minutes, 
2:00 + 3:00, or 3:00 + 2:00, or just 5:00, it winds up 
just short of first crack at 5 minutes.  Then I push it through first crack 
at 450 or 460, and punch cool when I like it.  If I want to stretch the 
roast I will try to program a next-stage temperature that will hold the temp 
that first crack finished at for some period of time, then either go to cool 
or go back  up to 450 - 460 to push into 2nd.  It involves a lot of trial 
and error to find a length of time for first crack that will let it finish, 
and a next-stage temp that won't drop the bean temperature significantly. 
Not to mention that I haven't really cared for the results.
So I'm back to pretty much just using Tom's tip sheet profile and watching 
and smelling the beans and smoke.  I can't hear the cracks.  Truthfully, I 
drag out my Precision occasionally because it is quieter and I can hear the 
cracks easily, which gives me more confidence in my roast than all the 
readouts on the iR2 and the thermocouple combined..  If it weren't that the 
Precision tends to arbitrarily dump the batch to "COOL" whenever I turn my 
back, I'd put the iR2 on eBay.  I just don't think the programming features 
are all that effective or practical.
What I really want is a Diedrich sample roaster with Jeffry Pawlan's 
computer control system, but I'll settle for just not ruining any of the 
coffe in the Panama Auction Set which should arrive tomorrow!  YESSSS!
You obviously have a grasp of the basics on your iR2, just keep roasting. 
Choose a simple profile and make small changes ONE at a time and take notes. 
Remember that Les, who has homeroasted for thirty years wrote (something 
pretty close to): " If I don't feel like a newby at least once a day I'm not 
trying hard enough."
Soon we'll be asking *you* for advice...
Michael Wade

4) From: Michael Wade
This is a multi-part message in MIME format.
Paul: 
Amen on the frustration.
A pot wouldn't carry the current that the heating element draws.  You'd =
need a variac, which is about the size of the iRoast, though shorter =
(and heavier).   From a design point of view, it's much too expensive to =
control the heavy current of the heating element, which is why they vary =
the fan speed to control the effective inlet air temperature.
I've thought about separating the heater and fan and running it like a =
popper, but that defeats the reason I bought it, which is to have a =
self-contained kitchen appliance that roasts coffee.  I'd love to have =
the two controls of the Gene Cafe on an iRoast3 with just a time and =
temperature display, temp from a probe in the beans.
But here we are, trying to get used to, if not command of, the machine =
as it is.
I just read MiKe's advice and it makes a lot of sense.  I think I'll do =
some more experimenting with extending the period after 1st crack, =
gently.  I'm definitely having trouble getting rid of low-roast sourness =
without getting into high-roast bitterness (which I hate!).
Michael

5) From: miKe mcKoffee
Thanks for the compliment Robert. Expertise?, let me make it clear I don't
consider myself a Roast Master by any stretch of the imagination! Probably
at about the College Sophomore level on my journey to a Doctorate in
Roastology;-)
BTW, didn't you move to the Corvallis, OR area or is my memory mistaken? If
yes consider this my personal invitation to come up and join us on the 24th!
Kona Konnaisseur miKe mcKoffee
Pacific Northwest Gathering IVhttp://mdmint.home.comcast.net/coffee/Rosto_mod.htmUltimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mdmint/pnwgIV.htmURL 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.
	From: homeroast-admin
[mailto:homeroast-admin] On Behalf Of Robert Yoder
	Sent: Thursday, June 15, 2006 8:18 PM
	Hi Mike,
	Thanks for this nice, clear and concise description of roast
profile.
	It is a pleasure to have the benefit of your expertise once again!
	robert yoder


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