A video that I came across from Giesen Webinar - Reading Coffee Beans for Profiling with Willem Boot, Marcus Young, David Sutfin and Katie Cates
Willem is the only person I have heard thus far explain the “exothermic” part of coffee correctly, when he says it is the heat of the coffee bean that has gone exothermic. Bless you Willem, I will never spell your name wrong again.
There are several videos that go over roasting and air profiling which I guess the Boot has spurred me to elaborate that yes I think air roasters should almost always do the opposite advice from a drum roaster in regards to how to apply heat, ex. if a drum roaster says “x bean needs lots of heat in the beginning”. I would agree completely (usually) (almost always) but I tend to tune out when they start talking about how to do it with the drum roaster, how to apply the heat, is what I mean to do the opposite. So in the webinar when they talk about high pressure, I don’t think that applies to air roasters because our air does not build a lot of back pressure. If someone knows how much back pressure is built up in the system given an air fan %, I would greatly appreciate it (@anyone). I assume it doesn’t because building a back pressure would mean that there would be resistance to air flow (our heat source) and thus counter-intuitive, also bean loft increases, meaning that to me, the limiting factor is the weight of the beans, the shape of the beans and density, roaster’s airflow path, and the ability of the roaster to push air. These variables are creating the resistance that is in our roast equation. However the beans are overrun by airflow, there is just so much pulling the equation on the negative pressure side and not the positive pressure side. But everything is on a bell curve, or sliding scale. So air roasters APPLY heat differently but to the beans it should/could feel the same drum roaster or air roaster. So if you want to fry a dumpling you could do it with oil, or air but not with water (combi ovens excluded), how you work with the medium using different tools can overcome the same variables.
The dirty deeds:
- If I try and reach 500F in 1min, with a 100% fan or 60% fan, both take longer than 90-80% fan
- At the end of the roast, if I am using an 85% fan if the roast fails, it will most likely be baked. If I had a 60% fan it will most likely develop charred notes
I use the fan to maximize the heat applied by the profile. That’s why I say it is best to find the temp profile with a flat 80% fan first and then try different fan settings to minimize or maximize the ROR or specific segment (like a flat end of roast).
If something I say does not make sense (here or previously) please quote whatever part and ask and I can elaborate.