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Permalink Reply by James Tooill on March 7, 2013 at 9:43pm

I'm surprised about the flame settings.  Are you using 50% flame until you're close to first?  If so, the first thing I'd try would be the increase that.  Should shorten the drying phase a little but the real point is to have more energy stored in the coffee so it'll hold momentum while you're gently guiding it through 1st.

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Permalink Reply by Eric Schaefer on April 15, 2013 at 9:07pm

Of course, what I'm about to say is personal preference, but I haven't had much luck with faster finishes.  Most of my profiles are full city, so maybe running a little longer than you're going for, but I'm usually going about 5 minutes between FC and SC, and maybe another minute or so before I drop.  For lighter, brighter roasts, I follow essentially the same profile, but just drop right around the SC onset.  The reason I don't like the faster finishes is that they always seem to take on a biting, bitter, tar/phenol sort of flavor that I don't get if I stretch things out a little.

For my tastes, the best way to brighten up your profiles would be to adjust batch sizes and early heat settings to get to FC faster.  My ideal profile is about 9 minutes to FC, although the Diedrich I most recently worked on had a hard time getting there as fast as I wanted.  I would roast some coffees in smaller batches specifically to get the faster ramp to FC and maintain more acidity and aroma.

Below are links to two example profiles I really liked while roasting on a Diedrich IR-24 (despite its implied capacity, I could never get more than about 30lbs to do what I wanted on that machine - 25 or so seemed to be ideal.)

http://www.beowulf-recording.com/download/coffee/Roast%20Data/data%...

http://www.beowulf-recording.com/download/coffee/Roast%20Data/data%...

P.S. If the charts seem a little weird, it's cause I've started graphing all of my roasts with FC as the "0" time mark.  It makes it easier for me to compare the different stages of the roast on various batches.

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Permalink Reply by Aaron Jordan on April 30, 2013 at 6:03pm

I figure I'll throw my two cents into the mass of recommendations. I roast on an IR-12 and as someone else stated, temperature and profiles don't translate directly even if on the same roaster. My suggestion would be to get a sooner drop out temperature, if you go any quicker on your drop out time you will probably start to see scorching/tipping. However, if I'm not mistaken, you want to utilize the moisture in the bean to propagate heat evenly from the inside to the outside to produce proper browning reactions. When you heat the outside cellulose matrix of the coffee without using the moisture content inside to your advantage scorching will occur and can flatten out the taste perception of the cup (which I understand you're not having a problem with). However, I have noticed that when profiling a coffee if my drop out temperature happens way below boiling point (any more than 20 degrees) even in lighter roasts dropped just post first crack can produce that flat acidity that you're experiencing. I have found the best results when my drop out temperature is 10-15 degrees before boiling point, on my IR-12 that means 180-190F.

Flat, bland, baked flavors generally (and this is very generally, there are other reasons as well) come from time spent in the roaster given the temperature rise. If minimizing roast characteristic and getting livelier acidity is what you want, I would recommend either using higher airflow (which will have to be counter-acted with lower heat because convectional heating will dry out the bean faster) or hitting first crack sooner (9:00-10:00) still keeping in mind that you don't scorch the coffee.

Hope this helps! Look forward to hearing your progress.

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