Gas-roasted and charcoal-roasted beans from the same origin taste different. We ran blind tastings to find out how much of that is real and how much is story.
The argument for charcoal roasting is partly practical: it produces radiant heat with almost no convective turbulence, which means the beans develop more evenly. No hot spots, no scorching. The argument against is that any good drum roaster can achieve the same result with gas if the operator knows what they're doing.
We ran blind tastings with the same Ethiopian lot — Yirgacheffe, natural process — roasted to the same degree (Agtron 58) by two methods. Participants ranked aroma, body, acidity, and aftertaste. Results: charcoal scored higher on body and aftertaste in 7 of 10 trials. Aroma and acidity were essentially the same.
Our interpretation: the cleaner, steadier heat of charcoal lets the bean's natural sugars caramelise more completely without the light smoky back-note that sometimes appears with gas. The effect is subtle but consistent.
The practical reality is that charcoal roasting is much slower and more labour-intensive. A batch that takes 14 minutes on gas takes 22-25 minutes over charcoal. The fire requires attention in a way that a calibrated gas roaster doesn't.
We think it's worth it. Not because of the story — because the cup is measurably better. If a blind tasting ever comes back flat, we'll reassess.