Coffee | One Roast at a Time

  • Gene Café CBR-301 Roast Experiments page

  • Brazil Santos – Between Batch Thermal Behaviour (Gene Café CBR-301)

    Context One of the practical questions that comes up when roasting multiple batches on the Gene Café CBR-301 is simple: How should the second, third and fourth roasts be adjusted when the machine is already warm? The Gene Café manual recommends starting from a cold machine. In practice, when roasting multiple batches this is rarely…

  • Roast 41 – Colombia Swiss Water Process Decaf

    First Decaf Roast on the Gene Café CBR-301 After more than forty roasts on the Gene Café CBR-301, Roast 41 marks the first time decaffeinated coffee has been roasted as part of the Coffee | One Roast at a Time project. Decaffeinated coffee behaves differently from regular green coffee. During the Swiss Water Process, caffeine…

  • Roast 39 & Roast 40 – Brazil Santos (Cold vs Warm Start Comparison)

    Key Metrics Summary Metric Roast 39 Roast 40 Coffee Brazil Santos (Wanted) Brazil Santos (Wanted) Batch size 250 g 250 g Ventilation Oven hood extraction Oven hood extraction Start condition Cold start Warm start Starting temp / ambient 20°C 75°C Time to 200°C 04:28 03:13 Time to 230°C 07:30 05:46 Total roast time 13:10 13:10…

  • What the Last 10 Roasts Taught Me About the Gene Café CBR-301

    A Pattern Emerging in Roasts 28–38 Over the past ten roasts, something interesting began to appear in the data. At first it felt like the roasts were simply getting easier. The machine seemed more predictable. The roast outcomes felt more repeatable. Looking more closely at the numbers, it turns out there is a clear reason…

  • Roast 38 – Colombia Regional Jess (Huila, Washed Blend)

    Gene Café CBR-301 | First Full Batch Roast After receiving the Regional Jess (Huila, washed blend), the goal of this roast was simple: Produce a clean, balanced full-batch roast to replace the earlier sample roast, which was useful for understanding the machine behaviour but not optimal for evaluating the coffee itself. This roast therefore serves…

  • Gene Café CBR-301 Ventilation & Smoke – What Roasting Looks Like in a Real Kitchen

    Key Observations Roaster: Gene Café CBR-301Environment: Indoor roasting (office) under standard kitchen extractor hoodVentilation: Passive hood extraction with aluminium duct directing exhaust airflow Smoke behaviour Ventilation effectiveness Smell vs smoke Ducting observations Airflow design Additional note Coffee | One Roast at a Time One of the questions that comes up repeatedly when people consider roasting…

  • Roast 36 & 37 – Brazil Santos (Natural) | Cold vs Hot Start Behaviour

    🔎 Key Metrics — Roast 36 vs Roast 37 (Brazil Santos, 250g) Roaster: Gene Café CBR-301Ventilation: Oven hood extractor (not directly ducted)Room temp: ~20–21°C 🟢 Roast 36 — Cold Start (20°C Drum) 🔵 Roast 37 — Warm Start (71°C Drum) 📌 Immediate Lessons This session wasn’t about flavour. It was about heat, airflow, and what…

  • Roast 35 – Kenyan AA Natural (Wanted) – Oven Hood Ventilation Calibration

    250g → 210.5g (15.8% WL)Cold Start | 250°C Set | Cool at 12:40 Context Roast 35 is the second roast of this Kenyan AA Natural and the first deliberate calibration roast under the new ventilation setup. Ventilation change: This roast was intentionally designed to reduce weight loss from Roast 34 (16.2%) toward the 15.0–15.5% range.…

  • Roast 34 – Kenyan AA Natural (Wanted) | First Roast with Oven Hood Ventilation

    Context Roast 34 marks two changes: The extractor is not directly attached to the Gene Café exhaust.It operates independently at full power during the roast, improving room air evacuation without mechanically pulling from the roaster. This roast therefore serves as: Green Coffee Details Roast Parameters Key Milestones Calculated Weight Loss 16.2% Observations During Roast Thermally,…