Green to Brown: How We Roast Coffee in Small Batches
Part two of our farm-to-cup series. Missed part one? Start with how we source green coffee.
Roasting is where green coffee becomes the thing you recognize — brown, fragrant, brittle enough to grind. Chemically, it's the most violent fifteen minutes in a coffee's life: hundreds of new aromatic compounds created, sugars caramelized, acids transformed, cell walls stressed until they crack — audibly. We do it in small batches on our Diedrich roasters, every single day.
Why small batches?
Because control beats volume. A small batch heats evenly, responds quickly when we adjust gas or airflow, and lets us roast to the coffee rather than to a schedule. It also means the bag you buy was roasted days ago — not months ago in a factory the size of an airport hangar. “Small-batch” isn't a vibe for us; it's the production method.
What happens in the drum
Green coffee goes into a preheated rotating drum. For the first minutes it just absorbs heat while moisture steams off. Then the color turns — yellow, tan, cinnamon — as sugars and amino acids begin the Maillard reaction, the same browning chemistry that builds flavor in seared steak and baked bread. Eventually the bean can't contain its own steam pressure and pops — first crack — the sound that tells every roaster the coffee has crossed into drinkable territory. What we do in the minutes around that crack defines the roast. (We go deep on the three phases of roasting — and our particular habit of stretching the middle one — in a post of its own.)
Roasting to a profile
Every coffee we sell has a roast profile: a logged curve of temperature over time that we hit batch after batch. Profiles aren't guesses — they're built by roasting a coffee several ways, cupping the results blind, and keeping the version that tastes best. Then the profile becomes the recipe, and consistency becomes the job. If Tuesday's Hi-Fi doesn't taste like Saturday's, we've failed — so we log every batch and taste constantly.
The feedback loop
The roaster isn't done when the beans drop into the cooling tray. Every production roast gets tasted — espresso on the bar, cuppings in the back — and what we taste feeds back into tomorrow's roast. Roasting is less like following a recipe and more like tuning an instrument that drifts a little every day: bean density changes as green coffee ages, humidity changes, even the weather leans on the machine.
Next in the series: the part you actually see — the bar, the bags, and how the coffee finds you.
