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 is removed while attempting to preserve the structure and flavour of the bean. However, the process alters the physical structure of the coffee slightly, which often results in:
- earlier colour development
- quieter first crack
- earlier smoke appearance
- slightly lower density beans
Because of these differences, this roast was intended primarily to establish a safe reference point for Swiss Water Process decaf on the Gene Café CBR-301 rather than pushing the roast toward extreme development.
Key Roast Metrics
| Metric | Value |
|---|---|
| Coffee | Colombia Swiss Water Process Decaf |
| Supplier | REDBER |
| Roaster | Gene Café CBR-301 |
| Batch Size | 250 g |
| Starting Condition | Cold start (~20°C room temperature) |
| Temperature Setting | 250°C |
| Total Roast Time | 13:00 |
| Weight In | 250 g |
| Weight Out | 214.2 g |
| Weight Loss | 14.3 % |
The final 14.3% weight loss places this roast slightly lighter than the typical decaf development range of roughly 15–16%, making it a useful baseline for future decaf roasts on this machine.
Roast Progression Observations
Rather than relying exclusively on first crack, the roast was guided primarily by colour, aroma, and total roast time, which are often more reliable indicators when roasting decaffeinated coffee.
Drying Phase
As the roast approached 200°C, the beans moved through the typical drying stage.
Visual changes included:
- green beans shifting toward pale straw colour
- slight expansion
- chaff beginning to release
Aromas during this phase were typical of early roasting:
- hay
- dry grain
- warm cereal
These signals indicate that internal moisture is being driven off and the roast is progressing normally.
Maillard Phase
Between roughly 200°C and 230°C, the roast entered the Maillard stage.
Colour development during this phase progressed from:
pale yellow → light tan → early browning
Aroma characteristics shifted toward:
- toasted bread
- warm grain
- subtle sweetness beginning to emerge
This stage is where sugars and amino acids begin reacting, forming many of the flavour compounds that will appear later in the cup.
Late Roast Development
Beyond 230°C, the roast entered its final development phase.
Several behaviours typical of decaffeinated coffee were observed:
- beans appeared darker earlier than expected
- smoke began appearing slightly earlier than usual
- first crack was quieter than many washed coffees previously roasted on the machine
For this reason, first crack was treated as an indicator rather than a strict endpoint signal.
Instead, the decision to stop the roast was based on:
- bean colour reaching medium brown
- aroma transitioning toward chocolate and toasted nuts
- total roast time approaching the planned guardrail
Cooling was initiated at 13:00 total roast time.
Roast Level Assessment
The final 14.3% weight loss indicates a medium-light to medium roast level.
For decaffeinated coffees, this is slightly lighter than many commercial decaf roasts, which are often pushed slightly further to compensate for structural changes in the bean.
However, this lighter development may offer advantages:
- cleaner flavour
- improved clarity
- less bitterness
Future roasts will explore whether extending development slightly improves body while maintaining balance.
Behaviour of Swiss Water Decaf
This roast reinforced several well-known characteristics of Swiss Water Process coffees.
Decaf beans often:
- darken visually earlier in the roast
- produce quieter cracking sounds
- generate smoke sooner than regular green coffee
Because of this, visual cues alone can be misleading, and roast control benefits from combining several signals:
- time
- aroma
- colour
- final weight loss
Using these signals together helps maintain consistent results when crack detection becomes unreliable.
Lessons Learned
Several useful insights came from this first decaf roast.
Decaf Appears Darker Earlier
Swiss Water decaf beans visually darken earlier than regular coffees. This can make the roast appear further developed than it actually is.
Crack Is Less Reliable
First crack was noticeably quieter than on many washed coffees previously roasted on the machine. For decaf roasting, time and aroma become more important indicators.
Weight Loss Remains a Reliable Anchor
The final 14.3% weight loss confirms the roast finished slightly lighter than typical decaf ranges, which provides a clear reference point for future adjustments.
A Useful Baseline Has Been Established
Even though this roast sits slightly below the typical decaf development range, it establishes a stable baseline for Swiss Water decaf on this machine.
Future roasts will likely explore:
- extending total roast time slightly
- targeting 15–16% weight loss
- evaluating how that affects body and sweetness
Where This Roast Fits in the Project
Roast 41 expands the Coffee | One Roast at a Time project into decaffeinated coffee roasting.
The objective was not to perfect a decaf profile immediately but to build a reference point for future decaf roasts on the Gene Café CBR-301.
Each roast builds a clearer understanding of how different coffees behave in this machine.
Final Thoughts
After more than forty roasts on the Gene Café CBR-301, the machine continues to show a consistent and predictable behaviour pattern.
Roasting decaf introduces a few additional variables, but the same core approach still applies:
observe the roast
trust the signals
adjust gradually
Coffee.
One roast at a time.