Hey Folks,
I just got back from a week’s vacation. I spent a few days up in Seattle and a few just hanging around in Portland. I can honestly say we’re doing better coffee in Portland by far (along with a slough of other things that are an entirely separate rant). Anyway, just before I left I came across a discussion among Roasters Guild members about the speed of the drum in the roaster. The basic question was, how fast does your drum rotate and have folks thought about it in relation to coffee cup quality? This got me thinking a lot about one of our machines at the roastery that’s set up with a fully variable drum speed motor and controls. Typically, it seems at least, Roasters don’t have this amount of immediate control of the the drum’s speed, and typically, most Roasters dial in an “ideal” speed for the drum and it runs constant throughout the process.
What I gathered through the dialogue was the drum speed can help control the rate of conduction and convective heat as it applies to the beans tumbling around in there. I took this fundamental factoid and asked, “If you can control heat transfer with the drum speed, then can I use the drum speed to improve/control the roast profiles better?”
Turns out, yes! I’m still working with how this effects the cup, but I have recorded better control of roast times and profiles, more even roasts and improvements in ideal capacity and output.
Once more data is collected, tested, compared and cupped, we will be able to apply profiles to our roasting process that preserve the density of our coffees better, improve the balance of conduction and convection with different beans from different altitudes and origins and thus ensure better preservation of our coffees’ natural characteristics of body, sweetness, acidity, etc.
I’ll keep you posted on this and other adventures in coffee roasting as they come up. Cheers.
