HomeRoast Digest


Topic: Troubleshooting woody flavors (3 msgs / 104 lines)
1) From: Mike Koenig
A question for all the "drummers"
I recently started roasting with my BBQ drum, which consisted of a
stainless cannister mounted on a homebrew shaft.  I was getting OK
roasts, but they seemed a bit slow, which I attributed to rather slow
heat transfer with a solid drum.
To correct this, I cut out three sections of the sides of the
cannister, and replaced them with perforated stainless mesh.  I have
three stirring vanes mounted on the still solid parts of the
cannister.  It holds roughly half a pound.
Since this is now perforated, I would expect some similarity to the
behavior of an RK drum, so I started by basing my profiles on what
I've seen others post for RK's, with some improvised adjustments for
the small batch size.  The result is rather woody tasting roasts (a
little like I'm chewing on one of those wooden coffee stirrers, with a
little burnt flavor thrown in).  The beans I roasted were some Monkey
blend and a Yirg.  I know I went too dark for the Yirg, but I didn't
expect such a wood taste from either bean.
I do know I need to nail down the position of my thermocouple tip,
since it moves around a bit, I tried the best I can to keep it roughly
at bean level.
Here is the basic profile I was using (all temps in deg F):
Preheat empty grill to 475 - adjust burners to maintain temp
Drop in loaded drum and start rotation
Adjust heat to a slow ramp to ~500 (took about 5 minutes - not at full
gas though)
Hit first crack at around ~13 minutes - cut back gas during first crack
First snaps of 2nd were around 15 minutes, pulled, dumped and cooled.
Given the fact that the thermocouple was free to flop around a bit,
I'm not assuming too much regarding the accuracy of the temp readings.
One remarkable difference is that most of the discussions talk about
needing full gas to ramp back up to ~500, whereas I was at 1/2 gas on
all three burners, and it still seemed to go rather fast, I backed it
down even more.  I use Weber grill if that makes a difference.
Anybody know of a specific cause for the woody taste?  I'll try a
roast later with the thermocouple more secure and see what happens,
but if I there are any suggestions on profile changes, I'd be
grateful.
Thanks,
--mike

2) From: Les
You are ramping up too slow and baking your beans.  Try starting at a grill
temp of 550 degrees and don't ramp up so high, but ramp faster.  I would
ramp up to about 480.  You are not getting enough time between 1st and
second.  When 1st crack starts drop your tempature some.  The beans are
giving off heat during 1st crack.  You don't need to add as much heat at
that time.  I don't want to get the endothermic and exothermic debate going
again.  I am simply speaking from experience.  On most roasts, I try to hit
first crack between 8:30 and 10 min.  I like to have 3- 4 minutes between
1st and the first snaps of second.  I usually end my roasts and 15-16
minutes.  I hope this helps.
Les
On 10/9/07, Mike Koenig  wrote:
<Snip>

3) From: Mike Koenig
Les,
Thanks for the input.  I tried a roast last night (between
thunderstorms).  Preheating to ~550 and keeping the heat higher after
dropping the drum in got me to 480 almost instantly.  Keeping it
(roughly) at 480 got me to first at around 10:30.  This morning, the
coffee is better, but still slightly woody.  I'll try another one
pushing it a little faster to first and see what happens.  I'm
thinking that I might still have some slow heat transfer, since the
drum is not totally perforated.  Maybe I'll try pre-heating the drum.
I'm going to try a "naked" thermocouple bead probe as well, vs. the
one I was using which was shielded in a metal tube.
Now I'm wondering at what point should I worry about 1) getting the
beans too hot before drying them, and 2) getting the ambient
temperature too hot?
After many years of struggling to slow down my air roasters (HWP and
then IR1) it never really occurred to me to try speeding up my roasts
in the drum.  It's a re-learning process for me.
Thanks!
--mike
On 10/9/07, Les  wrote:
<Snip>


HomeRoast Digest