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 from a cold machine.
Decaffeinated coffees often behave slightly differently during roasting. They tend to absorb heat more readily, produce a quieter or less distinct first crack, and can move rapidly through the final stages of development. For this reason the roast was approached with a steady profile and careful attention to colour and aroma rather than relying on audible cracking signals.
Roast Details
Roaster: Gene Café CBR-301
Coffee: Colombia Decaf (Swiss Water Process)
Batch weight: 250 g
Start state: Cold machine
Set temperature: 250 °C
Key Milestones
| Event | Time |
|---|---|
| 200 °C reached | 04:29 |
| 230 °C reached | 07:10 |
| Cooling initiated | 12:35 |
Input weight: 250 g
Output weight: 216 g
Weight loss: 13.6 %
The roast progressed smoothly without interruption and followed a stable heating curve typical of a cold start on the Gene Café.
No protection events occurred and airflow changes followed the machine’s normal behaviour.
Observations During the Roast
Colour development appeared even throughout the roast.
One of the most noticeable sensory cues came from the exhaust aroma late in the roast. Around the 11:30–12:00 mark the smell shifted from a toasted grain character to something sweeter and more reminiscent of sweet toast or lightly caramelising bread.
Because decaf first crack can be difficult to hear, this type of aromatic transition can be a useful signal that the roast is approaching full development.
Cooling was triggered shortly afterwards once colour and aroma appeared aligned.
Visual Result
At the end of the roast the beans showed:
- even medium brown colour
- matte surface
- no visible surface oil
The overall appearance is consistent with a light-medium to medium roast level, which is often a comfortable range for decaffeinated coffees.
Expected Cup Profile
Based on roast development and previous experience with similar decafs, the expected espresso profile should lean toward:
- cocoa
- biscuit
- soft caramel sweetness
- low acidity
- medium body
Decaf coffees often present a softer flavour structure than their caffeinated counterparts, so the goal here was to encourage sweetness and balance rather than push toward darker roast flavours.
Practical Notes
This roast reinforced a familiar pattern when roasting decaf on the Gene Café:
- audible crack can be unreliable
- colour and aroma become more important signals
- the final stage of the roast can move quickly
Watching the overall roast progression and responding to sensory cues remains more useful than relying on any single indicator.
As with all roasts in this project, the final evaluation will come from the cup once the coffee has had a few days to rest.