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Topic: Roasting interruptions and weird exothermy (14 msgs / 324 lines)
1) From: Jim Schulman
Hello,
I was asked to compare the taste of my variac-FR 
roasts with those of a roast with interuptions. So 
I did my regular espresso blend both ways today.
Being inquisitive, I decided to do the 
interuptions by turning the FR off, rather than 
putting it into cooling mode. I did this at the 
same place and the same length I usually turn down 
the heat, 1 minute into the second crack (later in 
the light weight FR than with the bigger thermal 
roasters). 
Imagine my surprise as the first crack continued 
unabated throughout the minute's off period. The 
beans at the end of their "rest" had an oil-shine 
and were at a light full city color. In contrast, 
turning the roaster down to 90 Volts, which 
produces an airflow of about 380F, stops the first 
crack in about 30 seconds, and keeps the beans 
lighter and drier.
I'm not sure what to make of this; but it seems 
the 380F airflow is actually cooling the beans, 
and they're roasting faster when sitting still.
In a second attempt, I gave it 5 seconds of 
cooling air, then let it sit. This stopped all 
cracking noises, and produced a roast time closer 
to my regular variac profile.
I'm not sure what to make of this, but I'm 
beginning to understand why people's results with 
roast interruptions are so inconsistent.
Jim
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2) From: sschlang
I want to thank-you for your intrepid experimentations.  As always, its 
fascinating.  I'm interested, though, in whether you noticed any difference in 
the taste/body of the roast.
At this point, I'm totally confused by the 
application of interruption/roast-extension with the Fresh Roast.  I roast for 
espresso.  When I first started with the FreshRoast Plus, I was bothered by the 
high notes that came blistering through...some extractions tasted like 
unsweetened grapefruit juice concentrate (well...not really...but close).  As a 
result, I started extending my roasts by using the cooling cycle.  At first I 
was doing it before second crack, however, I switched to doing it before first 
crack as well - having read that one of the caffein-o-scenti roasting houses 
ramped up for a long period before 1st crack.  What is the current thinking on 
this?  I do know that my espresso has improved immeasurably but some of that may 
also be due to a seasoning of my faux-barrista skills. 
<Snip>
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3) From: James Gundlach
On Tuesday, November 12, 2002, at 01:18 PM, Jim Schulman wrote:
<Snip>
Jim,
     You are not trying to bring the exothermic debate back are you?
Jim Gundlach
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4) From: Jim Schulman
First off, oops, I stopped the roast one minute 
into the first crack, not the second.
On 12 Nov 2002 at 20:41, sschlang wrote:
<Snip>
The beans are degassing. The moment of truth comes 
tomorrow.
<Snip>
La Minita reminds me of grapefruit; nice in a cup, 
not so nice in an espresso.
I'm doubtful that roast times prior to the first 
crack have much impact on the taste, since the 
beans are mainly warming up and drying out, not 
roasting. So I do my voltage control when the 
first crack starts, aiming to go five minutes from 
there to the roast's end. This produces the right 
degree of mellow for my espresso taste.
My goal here is to come up with an interuption 
technique that achieves the same results; which 
would be nice for people who want to keep their 
coffee lives simple. My idea was that shutting the 
roaster off at the same point I usually turn down 
the voltage would do the trick. We'll see if I'm 
in the ballpark tomorrow.
Jim
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5) From: floyd burton
maybe this should be called rostus interruptus-therefore it can't be a good
thing.

6) From: Jim Schulman
On 12 Nov 2002 at 15:06, James Gundlach wrote:
<Snip>
Heavens no, Jim. I meant it as a strange addendum 
that I can't quite figure out. For instance, does 
it mean the that if there's a brown out, the roast 
will finish if an airroaster is turned off, but 
will stall if it's left on?
Jim
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7) From: Ken Mary
<Snip>
I am guessing there may be some residual heat stored in the heater and
chamber walls. With no forced airflow to remove it the heat will continue to
be transferred to the cooler beans.
What puzzles me is the oil shine during first crack. By sitting in contact
with the hotter walls with minimal airflow, would a drum-roast effect be
introduced?
Now I have a whole new set of variables to add to my roasting experiments,
the "sit & cook" time, and placement within the profile. I do not want to
impose the sit & cook terminology so if there is a better term then I will
use it.
--
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8) From: Jim Schulman
Hi Ken,
You wrote:
<Snip>
The beans dried after cooling. But today, when I 
did the comparison espresso-cupping, they had a 
slight glow compared to the regular roast.
<Snip>
What about "rests?" Not sure how they would work 
in your ultra-fast roasts.
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9) From: Jim Schulman
An update on the interupted roast: 
I blind espresso-cupped the result next to my 
regular variac roast. It's not quite as sweet or 
heavy bodied as the regular result, but the flavor 
was a smidgen better without being sour. If I 
hadn't done it side by side, I wouldn't have 
noticed the difference, the result is well within 
shot to shot variation.
This is in big contrast to a straight FR roast of 
the same blend, which isn't nearly as sweet or 
heavy bodied. The blend has an Yrg component now, 
which I couldn't use in espresso with the straight 
Freshroast, because the sourness always outweighed 
the flavor at light colors.
So the one minute rest without cooling when the 
first crack gets rolling looks good as a way of 
slowing and mellowing an unmodified airroaster.
Jim
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10) From: Ed Needham
That is a really important observation Jim.  380F air actually cooling.  I'd
like to see an air roaster with a manual agitator, so that I could take
advantage of the phenomenon you just observed.  Heating the beans into first
crack with full air, then cutting or slowing the heat and air and just
agitating to assure evenness of roast.  Wow...The best of air and drum maybe!
Just thinkin out loud...
Ed Needhamhttp://www.homeroaster.comed
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11) From: Jim Schulman
Hi Ed,
You wrote:
<Snip>
I was worried about tipping or scrorching when I 
turned the roaster off, but I couldn't detect any 
defects like this in the finished roast. 
I'm guessing the bean to glass or bean to bean 
contacts are not conductive enough to scorch 
within the one minute I had it off. The FR has 
very little metal to bean contact, so I don't 
think an agitator is absolutely necessary. But it 
may be required for roasters that do.
In any case, it's certainly worth a few more 
experiments.
Jim
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12) From: Angelo
Just wondering if that roaster from Zach and Dani might not be what you're 
looking for. It does have that auger in the middle which, I suppose, is 
there to agitate the beans.....
Can't wait to read some reviews on that machine....
Ciao,
Angelo
<Snip>
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13) From: Andrew Thomas
--- "Jim Schulman"  wrote:
<Snip>
That's what I was wondering about. Next time I roast I am going to try this with my Poppery (I), which has lots of metal-to-bean contact -- if I can bring myself to risk sacrificing some beans.
<Snip>
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14) From: Ed Needham
Yeah...I've seen pics of that machine.  I even emailed them to see if they
were interested in having me do a review and put it up on my homeroaster.com
site.  I didn't get a reply .   I think there is
potential for a lower air flow roaster, with some agitation to possibly
achieve a roast with the best qualities of both a fluid bed roaster and a
drum.  Maybe after getting through the procrastination of finishing my other
roaster project, I can procrastinate even more on this one.
Ed Needhamhttp://www.homeroaster.comed
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