There’s something brewing in your roaster that’s leaving even the most seasoned roasters puzzled. You’ve got a batch of dry Ethiopian coffee from Sweet Maria’s, roasted on an SR 800 with an extension tube. Heat stays steady at three, airflow adjusted to keep beans moving but not frantic. First crack hits around seven minutes, development time just a minute. Yet here’s the rub: some beans look even, others are uneven, with hollow, less dense profiles. Is this a flaw in Ethiopian coffee, or a sign your process needs recalibrating?
The answer lies in the dance between heat, airflow, and bean structure. Ethiopian beans, especially from dry-processing, vary wildly in size and density. Some are compact, others more porous. When roasting, these differences create uneven heat absorption. The top four beans in your batch may have absorbed heat faster, leading to a quicker crack and a drier finish. The bottom four, slower to heat, retain more moisture, creating that hollow feel. It’s not a flaw—it’s a characteristic. But it’s also a clue.
Airflow is your key variable. You’re keeping beans moving, but maybe not enough. A slower, more controlled airflow could let heat penetrate evenly. Or consider adjusting development time. A longer development period might balance the roast, giving all beans time to dry uniformly. Also, check your drum’s preheat. If it’s not fully heated before starting, early beans may get a head start, leaving later ones behind.
Another angle: bean size. If your batch includes both small and large beans, they’ll roast at different rates. Small beans hit first crack faster, large ones take longer. Sorting beans by size could mitigate this. Or tweak your roast profile—start with a slightly lower heat to ensure even heating from the start.
Key points: Adjust airflow to slow heat transfer, extend development time for uniform drying, and sort beans by size to balance roasting.
Key points: Adjust airflow to slow heat transfer, extend development time for uniform drying, and sort beans by size to balance roasting.
What’s your experience with uneven roasts? Have you found a trick to even things out? Share your insights below.
Questions & Answers
What’s the difference between burning and simply uneven?
Burning involves combustion, releasing heat and light. Simply uneven refers to irregular surfaces or distribution, without chemical reaction.
Is burning the same as being uneven?
No. Burning is a chemical process with heat and light. Being uneven refers to physical irregularity, not a reaction.
Information sourced from industry reports and news outlets.
