Coffee | One Roast at a Time

Date: 22-Feb-2026
Roaster: Gene Café CBR-301
Batch: 250 g
Out: 209.4 g
Weight 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 at start; 2 → 3 at 04:21 (overheat event); fan remained at 3
Stir: 2 throughout; stepped to 3 at end
Crack Flag: Not recorded

Intent

This roast was designed as a controlled TRT hard-stop experiment to test whether 13:30 could function as a reliable upper boundary for Brazil Santos on this system.

Previous learning showed that TRT alone can mislead (Roast 25), so this test relied on:

  • Known airflow behaviour
  • Stable fan 3 convection after ~4:20
  • Established Santos response pattern

The goal was to push development toward the upper band without crossing into Roast 8 territory (~17.8% WL).

Measured Behaviour

Temperature Milestones

  • 200°C at 04:10
  • 230°C at 07:10
  • 245°C at 09:47
  • 250°C at 10:39
  • Plateau ~248–251°C to end

No crash, no runaway. Late roast stable under fan 3 convection.

Weight Loss Outcome

16.2% WL confirms this is materially developed and clearly in the upper band for this coffee.

Visual Assessment (vs Roast 8)

Side-by-side comparison shows:

  • Roast 26 is meaningfully lighter than Roast 8
  • No visible oil or surface sheen
  • Uniform dark brown with slight natural variation
  • A small number of darker beans
  • A couple of visible quakers

Roast 8 appears almost glossy in comparison and remains the upper “too far” reference.

This confirms Roast 26 did not cross into the fatigue zone.

Aroma (Morning After)

  • Dominant: dark chocolate
  • Secondary: warm nutty notes
  • Impression: full, rounded, no sharp edge
  • No acrid or ashy character
  • No oil migration visible at this stage

Aroma aligns with controlled upper-medium development rather than dark roast.

Interpretation (Held Carefully)

Roast 26 demonstrates:

  • TRT 13:30 can produce ~16.2% WL under current Santos + airflow conditions
  • The roast remains below visible oil migration threshold
  • Structural development appears deep but controlled
  • This may represent a credible upper boundary for Santos on this setup

Important nuance:
This outcome occurred with an overheat-triggered fan shift at 04:21. Repeatability must be validated.

Working Hypothesis

For Brazil Santos (250 g, 250°C set, typical overheat → fan 3 behaviour):

  • 13:00–13:20 likely mid-upper band
  • 13:30 behaves as upper boundary (~16% WL)
  • Beyond this likely approaches Roast 8 fatigue zone

This remains provisional pending repeat confirmation and espresso testing.

Next Step

Primary validation will come from espresso:

  • 20g in
  • ~40–42g out
  • ~28–32 seconds

Key observation points:

  • Roundness vs heaviness
  • Dryness in finish
  • Body and crema stability
  • Sweetness persistence

If extraction is balanced and free of dryness, 13:30 may represent the Santos ceiling for this system.

Position in Project Context

Roast 26 is not a “profile.”
It is a boundary test.

If repeatable, it becomes a guardrail.

If the cup contradicts the structure, it remains a data point.

One roast at a time.