If I had to guess, this result is from the fairly straight RoR curve on this last roast. On the two roasts posted earlier, one had a small crash/flick, the other had 8% DTR and might have been a little underdeveloped.OldmatefromOZ wrote:This is by far the best coffee I have roasted to date, its sweet, full and rounded cup with no detectable roast defects. Makes my previous roasts seem weak and wispy, a bit undeveloped and baked.
If I could make a recommendation, adjust your Artisan Config>Axes>∆Axis>Max setting to maybe 22*C. This will uncompress the RoR curve and show more detail. No reason not to have RoR displayed on the entire graph.
And for clarity: I used a constant airflow setting for the past year+ and was very happy with the results. My coffee was clean, dynamic, very sweet and free of roast defects. The air setting used was just enough to evacuate most of the chaff. It was about 20% below the setting that yielded max heat transfer. I could have been very happy leaving well enough alone.
But I'm finding that starving the system of air in the beginning of the roast has its benefits, but not without consequences. Maintaining a straight declining RoR is easier with steady air and not too much of it. Having lots of air blowing through a drum roaster makes controlling RoR harder.
Making air adjustments mid-roast also makes life harder with only marginal gains in the cup. Before I was able to use 3 roast profile templates for all my coffees. I had a city+ profile, a FC profile and a fast city profile used mainly for African coffees. Now, if I want to really nail the RoR slope, I need a separate profile for every coffee.*
The trick for me is achieving the same roast profile, with less initial airflow. This requires a bit more heat to push a roast through the turn and get it ramping up to the same degree as it did when I used more air. I'm finding I need 60-70% burner now where I used to use 50%.
So my intent of low air during dry might be different that MCR. Joe says its to prevent the outside of the bean from heating too fast before the inside has a chance to catch up. I do it to promote more conduction and less convection. The effect might be the same, but if I'm reaching DE in say 5 minutes either way, am I really slowing the transfer of heat? Regardless, I'm find less air in the beginning results in a softer, more nuanced cup.
*Different density coffees take on heat differently. And different sized beans also take on heat differently. So even with the best picked and prepped coffees, this is anything but an exact science.