[Homeroast] Quest M3 improving the roast with Larger Batches

Hank Perkins hankperkins at gmail.com
Mon Feb 14 15:18:35 CST 2011

Afternoon.  Over the last month I have been working to get the flavor
equivalent from a 230g batch that I get from a 125g batch.  This has
been a challenge.

Around 1 Jan I got the Quest thermcoupled, and purchased the Omega
HH806AU Data Logger. I have this connected to my Mac running Artisan.
This gives me a real time graph of the roast.  To get the particulars
here go to Home Barista and search for Artisan.

The biggest advantage I have found is watching the graph develop and
asses the rate of change for the ET and BT.  With 125g I can hit 1C at
7-8 min.  What I have attempted to to with the 230g load is mimic the
time and bend the curve as to slow the rate of rise from mid C1
through EOR allowing the flavors to develop.  Today was my first time
to accomplish this successfully.  The issue here is how low the temps
go after charging.  With 125g I will hit ~250 with 230g I will hit
200.  Please note, I am not anal about absolute temps here.  Changes
in the beans, bean charge temps, ambient temps, humidity, a gram here
a gram there IMO is not going to make substantial differences.

Here is what I did.  I Charge the roaster between 400 and 405 degrees
with the Amps set at 8 and the fan barely blowing I want ET and BT
rising when I charge.  With 230g the BT will drop to ~200 degrees
(+-10).  Once the ET begins to drop I run the temp wide open.  When
the ET begins to climb I begin adding fan speed.  I don't want to kill
my rise here.  I want to go hot  I want the ET to be between 625 and
650 with my fan speed between 6 and 7.  At this point I am along for
the ride.  As my bean temp gets between 5-10 degrees from where it
will hit C1 (between 380 and 405 depending on the bean) I begin to
back off on the amps but not much and not fast.  Some beans like the
jimma require a quicker reduction some don't.  Once I hit C1I pull the
amps down to 5 and within 30-45 seconds I ramp the fan wide open.  Now
If I do this right 1/2 way through C1 the curve will bend and flatten
out. I then ramp the amps back up and cut the fan back down after 45 -
60 seconds.  Generally I want to keep the ET here above 550 depending
on the bean. I dropped the beans once they hit C2.  Once the roasts
were complete the look and smell was identical to roasting 125g

With the 5 roasts I did today I hit it in every case except the Monkey
Espresso Blend.  I was not successful in bending the curve here.  I
expect this has to do with the different origins of the beans in the
blend.  Maybe Tom will weigh in here without disclosing the magical

In a few days I should be able to report on the success or failure
from a taste standpoint. But the time and profiles were real close.


More information about the Homeroast mailing list