Phase 1: Drying Phase
Temp: 0-150C (300F) | Duration: 4-6 min (30-40%)
Water evaporates (11% to 2-3%). Beans turn green to yellow to golden. Grassy/hay smell = chlorophyll breakdown. Endothermic (absorbs heat).
Roasting Science
The chemistry that transforms 1,000 green bean compounds into 1,500+ flavor molecules
The Three Phases
Phase 2: Maillard & Caramelization
Temp: 150-196C (300-385F) | Duration: 3-5 min (30-40%)
WHERE MOST FLAVOR IS CREATED. Amino acids + sugars produce pyrazines (nutty), furans (caramel), thiols (coffee aroma). Caramelization produces butterscotch, sweet compounds.
Phase 3: Development
Temp: 196C+ (385F+) | Duration: 1-3 min (15-25%)
Defines roast level. First crack at ~196C = steam/CO2 fractures bean. This is where DTR matters most.
Roast Levels
| Level | Temp | Flavor Character | Best Method |
|---|---|---|---|
| Light (Cinnamon) | 196-205°C | Origin-forward, bright acidity, floral, fruity | Pour-over, AeroPress |
| Medium-Light (City) | 210-220°C | Sweet spot — acidity + sweetness balanced | Pour-over, filter |
| Medium (Full City) | 220-230°C | Chocolate, caramel, nuts, balanced | Drip, AeroPress, espresso |
| Medium-Dark (Full City+) | 230-240°C | Bittersweet chocolate, smoky, reduced acidity | Espresso, moka pot |
| Dark (French) | 240-250°C | Bitter, smoky, charred. Origin lost. | Espresso blends (traditional) |
Rate of Rise (RoR) Problems
| Problem | RoR | Result |
|---|---|---|
| Scorching | Too high early | Burnt, smoky, bitter |
| Tipping | Too high late | Dark spots on edges, ashy |
| Baking | Crashes to 0 or negative | Flat, bread-like, papery |
| Stalling | Flattens mid-roast | Under-developed + roasty |
| Flick | Spikes at end | Uneven — bitter/sour mix |
Resting Windows
| Method | Min Rest | Peak | Stale |
|---|---|---|---|
| Espresso | 5-7 days | 10-21 days | 5-6 weeks |
| Pour-over / Filter | 3-5 days | 7-21 days | 4-5 weeks |
| French Press | 3-5 days | 7-21 days | 4-5 weeks |
| Cold Brew | 1-3 days | 5-14 days | 4 weeks |