Notes
Real roast records, not recipes.
A browsable archive of Gene Café CBR-301 roasts, machine-state observations, cup results, mistakes, repairs, and learning checkpoints.
How to read these notes
These pages are records of what happened on a real machine, with real batches and real judgement calls. Treat them as evidence, comparison points, and context — not as universal profiles.
The useful pattern is usually the loop: batch size, start state, target temperature, total roast time, weight loss, cup result, and what changed next.
Useful entry points
Project checkpoint
Roast 120 to Roast 148
The point where the project became much more clearly about machine state, tools, logging, and the limits of simple profile thinking.
Archive
2026 roast notes
The main working archive of roast records, comparisons, calibration attempts, repair notes, and learning posts.
Small batches
Sample roasts
Small sample roasts are useful for observing machine behaviour, recovery, and whether a tiny batch can still produce useful learning.
Browse the notes archive
The cards below are generated from the live WordPress notes archive, so new published notes can appear here without rebuilding this page by hand.
From Roast 120 to Roast 148: When the Gene Café Project Became a Machine-State Story
The last proper website update was around Roast 120. At that point, the Coffee | One Roast at a Time project was already well beyond the earliest “what…
Crack Monitoring on the Gene Café CBR-301: A Small Progress Update
A cautious update on my ongoing experiment to use audio, roast data, and manual notes to better understand first crack on the Gene Café CBR-301. It has been…
Four Personal Roasts: Sweetness, Decaf, and an Awkward Pacas Lesson
Date: 25 May 2026 This was a small personal roasting session on the Gene Café CBR-301, aimed mainly at coffees for pour-over and Fellow Aiden brewing. The intention…
Gene Café CBR-301 300g Roast Test Went Wrong
I had planned a simple 300g consistency test on the Gene Café CBR-301. The idea was to roast three batches back-to-back: Roast 112 — cold start Roast 113…
Roasts 107 & 108: A Cold/Warm Swiss Water Decaf Pair That Stayed Lighter Than Expected
These two roasts were planned as a useful comparison pair. Same coffee.Same machine.Same batch size.Same target temperature.Different start state. The coffee was REDBER Colombia Swiss Water Decaf, roasted…
How the Gene Café JSON Roast Report Beta Evolved
When I first started using the Gene Café CBR-301 app, one thing stood out immediately. The app gives access to roast data. That matters. Not every coffee roaster…
Roast 103: First Swiss Water Decaf on the Restored Heater
REDBER SWP Decaf Personal Gene Café CBR-301 | Restored-heater phase | Personality 3 This roast was the first decaf I have roasted on the restored-heater version of my…
Four Roasts on the Restored Heater: What I Think the Gene Café CBR-301 Is Doing Now
After the correct replacement heater was installed in my Gene Café CBR-301, I did not want to assume the machine had simply gone “back to normal.” That would…
Roast 99 Note Draft
Brazil Yellow Bourbon Natural BR2504 — First Restored-Heater Validation Roast Coffee: Brazil Yellow Bourbon Natural BR2504, 88grainesRoaster: Gene Café CBR-301Machine state: Newly replaced 220 V heater installedBatch: 250…
Roasts 95–97 – Three Honduras Field Notes and a Quiet 100th Roast Event
Last roasts of the day This was meant to be a tidy little roast session. Two roasts of the same Honduras Catuai Natural. One cold start. One warm…
Would I Still Recommend the Gene Café CBR-301 After 100 Roasts?
This is a field note after 100 roasts on the Gene Café CBR-301. It covers what I actually think of the machine now — not first impressions, not…
Roast 93 and 94 – End-of-Bag Personal Roasts
Ethiopia Karume Natural (247.4g) and REDBER Decaf Colombia Swiss Water (257.5g) These were two end-of-bag personal roasts done to finish what was left in each bag. That made…
Roast 91 and Roast 92 — Same Plan, Different Result
Roast 91 and Roast 92 were supposed to be simple. That was the point. Same coffee.Same batch size.Same target temperature.Same cold-start intent.Same total roast time. In other words,…
Roasts 84 to 91 – Stabilising the Current Heater, Not Pretending It Is Normal
Roasts 84 to 91 ended up being a very important block. Not because every roast was perfect.And not because this suddenly turned the Gene Café CBR-301 into a…
Roast 80–83 – Control Inputs vs Outcome (Honduras, Washed)
Context These four roasts were part of a focused attempt to understand what the controls on the Gene Café CBR-301 actually do in practice. The goal was not…
Post-Heater Recalibration, What Actually Changed
Introduction This note captures what changed after replacing the heater in the Gene Café CBR-301, and how the system was recalibrated using real roasts. It is not a…
Roast 70–75, The Repaired Gene Café Has a Different Fingerprint
The last six roasts have made one thing much clearer. The repaired Gene Café CBR-301 does not appear to be a simple version of the old machine that…
Roast 74 and 75, Honduras Calibration Pair After Repair
The purpose of this pair was simple: stop drifting beyond target and generate a cleaner post-repair comparison. Roasts 72 and 73 were useful, but they were not strict…
Post-Repair Recalibration, Where Things Stand After Four Roasts
When the heater was replaced, the obvious question was whether the machine would behave the same as before. The answer, after four post-repair calibration roasts, is no. Not…
Roast Interruption – Gene Café CBR-301 (E4 Error)
Roast Interruption – Gene Café CBR-301 (E4 Error) This note documents a recent interruption during roasting and the steps taken afterwards. It sits outside normal roast analysis, but…
One | Roast at a Time | Note – Roaster Failure (Mid-Project)
Context Up to this point, the Gene Café CBR-301 has been central to everything in this project. Every roast, every observation, every small pattern that has started to…
One | Roast at a Time | Roasts 51–66 – Multi-Coffee Validation
Overview This set of roasts spans four different coffees and three processing styles: washed, natural, and wet hulled. The purpose was not to refine one coffee in isolation,…
A Note on Consistency and Control
Most home roasting advice talks about control as if it’s something you can dial in from the first roast. In practice, it doesn’t quite work like that. What’s…
Why I Don’t Use a Bean Temperature Probe on the Gene Café (For Now)
One of the most common questions that comes up when roasting coffee is simple: What is the bean temperature? On most commercial drum roasters, that number is central…
Roast 50 — Colombia Supremo (Washed)
Batch:250 g | 250 °C | Cold Start TRT: 13:21 | Weight Loss: 16.0% This roast marks the first Colombia Supremo roast in the project and serves as…
Observation: Airflow Behaviour Around ~200 °C on the Gene Café CBR-301
Context Over time, a recurring observation during roasting on the Gene Café CBR-301 began to stand out. Across many roasts, the machine appeared to change behaviour around the…
Roast #49 – Honduras Pacas (Washed)
Finca El Paraíso — Santa Barbara, HondurasProducer: Wil Edilberto ArmijoVariety: Pacas (Bourbon mutation)Altitude: 1550 m This roast was intended as a personal roast for drinking, but also provided…
Roast 48 – Colombia SWP Decaf (Swiss Water Process) | Personal Roast
This roast was carried out as a simple personal roast intended for home espresso. The coffee was a Colombia Swiss Water Process (SWP) decaf, and the roast began…
Roast 47 – Ethiopia Karume (Natural)
Warm Start Personal Roast The second roast of the evening used Ethiopia Karume and was started shortly after the cooling cycle from Roast 46 had completed. The machine…
Roast 46 – Brazil Topazio (Natural)
Cold Start Personal Roast This roast was carried out as a simple personal roast for home consumption. The goal was not experimentation, but to produce a comfortable everyday…
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…
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…
Roast 39 & Roast 40 – Brazil Santos (Cold vs Warm Start Comparison)
Key Metrics Summary MetricRoast 39Roast 40CoffeeBrazil Santos (Wanted)Brazil Santos (Wanted)Batch size250 g250 gVentilationOven hood extractionOven hood extractionStart conditionCold startWarm startStarting temp / ambient20°C75°CTime to 200°C04:2803:13Time to 230°C07:3005:46Total roast…
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…
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…
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 Little to no…
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 —…
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…
Roast 34 – Kenyan AA Natural (Wanted) | First Roast with Oven Hood Ventilation
Context Roast 34 marks two changes: New origin — Kenyan AA Natural (Wanted Coffee) New ventilation configuration — kitchen oven hood extractor replacing prior active exhaust setup The…
System Reflection — Thermal Memory on the Gene Café CBR-301 Is Not Subtle
Roasts 32 and 33 were designed as a controlled comparison on the Gene Café CBR-301. Cold start versus warm start.Same Brazil Santos coffee. Same 250g batch size. Same…
Cold vs Warm Start | TRT Discipline | Upper Guardrail Defined
Roast 32 & Roast 33 — Brazil SantosThese two roasts were deliberately paired. The intention was simple:Test repeatability using Total Roast Time (TRT) as the primary control variable,…
Brazil Santos Natural — Gene Café CBR-301 Sequential Heat Saturation Session
250 g batches | 250°C set | 4 consecutive roasts Objective To test: How the Gene Café CBR-301 behaves across multiple back-to-back 250 g roasts. Whether cooling to…
Brazil Santos Natural | 250g → 207.4g (17.0% WL) | TRT Validation (Airflow Inflection)
Context Roast 27 was designed as a TRT (Total Roast Time) validation test. The working assumption was: Cooling at ~13:30 should consistently land near ~16% weight loss. Roast…
Roast 26 – Brazil Santos (Natural) | TRT Push Upper Boundary
Date: 22-Feb-2026Roaster: Gene Café CBR-301Batch: 250 gOut: 209.4 gWeight Loss: 16.2%Set Temperature: 250°C (initially 248°C, corrected at ~3:00)Total Time: 13:30 (cool initiated at ~13:31 logged)Fan: OFF → 2…
Note – Roast 25 | When Time Wasn’t Enough
Roast 25 was meant to be simple. Brazil Topazio.250g.250°C set.No mid-roast adjustments. The only deliberate change was the stopping logic: a fixed cool at 13:03. No chasing weight…
Note – On Repeatability, Correlation, and the Urge to Overcomplicate
There’s a moment in this process where curiosity quietly turns into doubt. After consolidating the roast data into a single CSV and looking at correlations between weight loss,…
Sample Roast 3 – Regional Jess (Huila, Washed Blend)
Sample Roast 3 was a 56 g washed Colombia micro-batch that landed at 14.6% weight loss with 1:22 development after the first-crack button press. A temporary gasket fix…
Sample Roast Comparison – 52g Batches on the Gene Café CBR-301 | Machine Behaviour Study
Why this comparison exists These two roasts were not about flavour discovery. They were a controlled check: Does the Gene Café CBR-301 behave like itself when the batch…
Roast 24 – Brazil Santos Natural – Wanted Controlled post-crack development extension
Brazil Santos Natural – WantedIn: 250g → Out: 211.3g (15.5% WL)Intent: Controlled post-crack development extension Measured Data Batch size: 250g Target temperature: 250°C Weight loss: 15.5% Roast 24…
Roast 23 – Wanted Santos Arabica (Natural) | Espresso Baseline 1
17 Feb 2026Brazil Santos Natural – WantedIn: 250g → Out: 212.5g (15.0% WL)Intent: Santos espresso baseline Measured Data Batch size: 250g Target temperature: 250°C Weight loss: 15.0% Roast…
Roast 17 — Ethiopia Guji Karume (Natural)Espresso Calibration Morning
Espresso Calibration Morning Coffee: Ethiopia Guji KarumeProcess: NaturalBatch: 250gWeight Loss: 14.1%Rest: 8 daysIntent (originally): Not explicitly espresso-focused Context This morning wasn’t supposed to be significant. It was simply…
Roast 22 – Guatemala Acatenango, Caturra (Washed) | Lower Structural Target | 15.5% WL
Date: 15 February 2026Machine: Gene Café CBR-301Batch: 250gSet Temperature: 250°CPreheat: NoCooling Initiated: 12:25 (745 seconds)First Crack (logged): 11:20 (680 seconds)Development Time: 65 seconds (crack to cool)Weight In: 250gWeight…
Roast 21 – Guatemala Caturra (Washed) | Alignment Attempt
Roaster: Gene Café CBR-301Batch: 250 gSet Temp: 250°CPreheat: NoneFan: 2 → 3 at 4:27Cooling initiated: 12:51 (771 s)Output: 210.1 gWeight Loss: 16.0%Development (from crack flag): 83 s Intent:Repeat…
Roast Notes – After 22 Roasts on the Gene Café CBR-301
Last Updated: February 2026Roasts Included: 22 total (20 standard + 2 sample roasts)Roaster: Gene Café CBR-301Baseline: 250 g | 250 °C | Fan 2 → 3 around ~4…
Roast 20 – Guatemala Caturra (Washed) | Washed Central America Contrast
Roaster: Gene Café CBR-301Batch Size: 250 gSet Temperature: 250°CPreheat: NoneAirflow: Fan 2 → 3 at ~4:00Cooling initiated at: ~13:10 (approx.)Output Weight: 209.7 gWeight Loss: 16.1% Role / Intent:Washed…
Roast 19 – Honduras Catuai (Washed) | Reset Palate / Washed Baseline
Gene Café CBR-301 | Active Exhaust Baseline In / Out: 250 g → 214.3 gWeight Loss: 14.3%Set Temp: 250 °CEnd Decision: First crack + 80 secondsCooling: Initiated deliberately…