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Topic: Profile roasting adjustment (5 msgs / 166 lines)
1) From: AlChemist John
I have been profile roasting with an adjusted WBI for the last month or 
so.  Standard procedure is that I give it full heat for about 3 minutes and 
then short cycles (3-4 sec) with the heater off until about 300 F.   It 
then proceeds fully to first crack at 325.   At that point I start 
cycling  the heater every 30 seconds or so to keep the temperature rise at 
about 10-15 degrees a minute.  Presently, the goal is 7 minutes between 350 
and 425 degrees ( where I am stopping most roasts).
I have noticed that with this profile, the beans are very consistent and on 
the outside look the same as the 4-5 minute non profile roasted beans, but 
the overall ground color is darker on the profile 
roasted.  Correspondingly, I notice the "darker" roast notes in the 
cup.  Whereas I like in general what the profiling is doing for the cups, I 
seem to be getting a little bit darker than I can for.  I have dropped that 
final temperature on this weeks roasts to 410 and pulled the whole roast 
time back about 2 minutes.  It helps some, but not fully.
Does any one have a feel or experience to address the following:  If I drop 
my final temperature to say 390 (just for instance), should I shorten the 
roast by another minute or so or try a  slower ramp so that the roasting 
time (325-end temp) is always constant?
In general, I like what the profiling does for acid degradation and 
addition of body, but I seem to have lost some of my beans sweet spots.
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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2) From: Ken Mary
You do not say where your end point is in regard to second crack. In my 
experience, any more than a few snaps of second gives undesirable roast
I believe that it is not good to interrupt first crack by turning off the
heat, but I have no proof.
Changing the ramp and final temperature will have different, but somewhat
interchangeable effects. Temperature determines roast degree, higher temp
will give more "roast" flavors. Slower ramp may allow some reactions more
time to complete. This may be good or bad depending on your personal
preference or brew method. Slower ramps may allow more loss of volatile
You should not change too many variables at once. With each profile, change
the final temp and taste the results. Then choose a new profile and do the
Temperature measurement in an air roaster has many sources of error. Your
final temperature for best flavor may be different depending on which
profile you use.
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3) From: Mike McGinness
Learn the answers to all those questions for all your different greens and
you will have earned the title of Roast Master. I'm far from it myself. All
you can do is experiment. Re-read those Dietrich articles on roast
bracketing etc. I could say what I'd do for my taste but that isn't
necessarily what would taste best to your palate. I did a roast of Songbird,
light city, about 400, total roast time 13min that surprised the heck out
me. Never had that light a roast taste that good, have that much body or
complexity. Though I haven't repeated that roast since, I usually go a bit
darker, though most roasts still pre or just to very beginning of 2nd. As a
'sort of general feeling developing into a sort of rule of thumb' when I'm
going for a lighter roast I slow the 1st crack development versus a darker
roast. But not that much difference... I'm sure this has done nothing but
further confuse but that's what I'm here for!;-)
Anyone can roast coffee, taking the time to fine tune the process making it
just that much better, that's where the art comes in as well as science,
keep at it John!
Variable Variac Rockin' Rosto Roasting in Vancouver, WA USA

4) From: AlChemist John
Sometime around 09:09 10/4/02, Ken Mary typed:
I have been just shy of 2nd crack in most cases.   As my thermometer is 
set, 2nd occurs at 425, and the roasts have been going to 420 - 425.
I have heard this also but am not so much interrupting 1st crack as quickly 
cycling the heat to keep the temperature from rising to quickly.  I am not 
actually stalling the roast.  OTOH,  when I have stalled the roast, I found 
no particular taste impact.
That was/is the general premise I am working under.  It is mainly that with 
a slower ramp I am getting more roast flavor.  I like the fuller body of a 
slower roast, but do not care for the roast flavor as much.  Any clue at 
what temperature (or reference mark) roast flavors start to become 
pronounced.   In that I only noticed that flavor if I brought a non-profile 
(FR for instance) roast  well into 2nd crack, I am finding it odd to find 
that flavor pre-2nd crack.
I have done my best to minimize this error by mounting the thermometer in 
one constant place and always using the same quantity of beans.  My 
temperatures may not match others on the list (or they might), but they 
appear consistent to themselves.
John Nanci 
AlChemist at large
Roasting and Blending by Gestalt
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5) From: Ken Mary
I found roast data from my early attempts at profiling in Jan '01. The
roaster (Melitta Aromaroast) was preheated to 200C as measured in the air
above the bean level, beans added (Brazil Cerrado), 200C regained at the 2
minute mark and maintained about 30 sec. At this point the temp was ramped
at 6.6C per minute to 233C over 5 minutes to the 7.4 minute mark where
second crack began. The temp was stable at 233/234 until the end at 8.0
minutes. The second crack "snap rate" was estimated at 2 to 4 per second.
There was very little if any "roast" or unpleasant flavor. This is the
farthest into second crack I have ever roasted with no unpleasant flavors.
The main problem is that the complexity is gone, so I never bothered to
repeat this profile.
My other data seem to show that faster ramps lead to more roast flavor
earlier in second crack, which is opposite from what you have described,
unless we are talking about different flavor sensations. My preference at
that time was a 10C per minute ramp stopped short of or at most a few snaps
into second.
I (or both of us) could have had some mixing problems which resulted in some
beans being overdone, and bad flavors too early in the profile.
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