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 them slightly unusual, but also quite useful.
Neither roast used the standard 250g batch exactly. One was slightly under. One was slightly over. On paper that can feel like something that should matter. In practice, what these two roasts reinforced was something more useful: on this machine, small deviations around 250g matter less than machine state and coffee type.
That is the real lesson here.
Roast 93 — Ethiopia Karume Natural
Roast 93 used 247.4g of Ethiopia Karume Natural and produced 210.5g out, for 14.9% weight loss.
This roast was effectively a cold start, beginning around 22°C, with a 250°C set temperature. Total roast time was about 13:21.
In practical terms, it behaved like a normal 250g cold-start roast. It moved through the roast cleanly, fan behaviour looked normal, and it landed in a sensible place for personal pour over.
That is the useful part.
Being 2.6g under the nominal batch size did not appear to create any meaningful problem. It did not become unusually fast, unusually unstable, or awkward to read. It simply behaved like a standard personal roast and landed at a development level that should suit filter brewing well.
For this machine, that is reassuring.
A batch that is a gram or two light does not appear to need special treatment.
Roast 94 — REDBER Decaf Colombia Swiss Water
Roast 94 used 257.5g of REDBER Decaf Colombia Swiss Water and produced 220.9g out, for 14.2% weight loss.
This roast began on a warm machine, starting around 69°C, with a 249°C set temperature. Total roast time was about 12:45.
This was the more technically interesting of the two roasts.
The batch was slightly heavier than normal, but the warm start still dominated the roast. It moved quickly through the middle of the roast, reaching 230°C at about 6:02 and 245°C at about 7:55. That is a strong reminder that on this machine, a warm start can matter more than a small increase in batch size.
That is what made this roast useful.
The extra 7.5g did not slow things down enough to offset the warm-start momentum. Even with a slightly lower set temperature, the roast still carried well and landed further on than I would ideally target for a lighter personal decaf pour over.
That does not make it a failed roast. It should still be perfectly drinkable. But it does place it more toward the fuller end of personal filter decaf rather than the lighter side.
What these two roasts reinforce
Taken together, these roasts make the same point from two different directions.
The first roast shows that being slightly under 250g is not a meaningful problem in itself.
The second roast shows that being slightly over 250g does not cancel out a warm start.
That matters more than the exact bag-ending weights.
The practical takeaway is simple:
- small end-of-bag batch differences around 250g are usually manageable
- start condition matters more
- coffee type matters more
- and on this machine, those are the variables worth respecting first
For Roast 93, the cold-start Karume behaved like a normal 250g roast and confirmed that a slightly smaller batch could still land very cleanly for pour over.
For Roast 94, the warm-start decaf showed that the machine still had enough momentum to run quickly, even with a slightly heavier batch and a 249°C set point.
Practical lesson going forward
For personal end-of-bag roasts on the Gene Café CBR-301, I would not overthink a batch in the 247g to 258g range.
That is not nothing, but it is not the first thing I would worry about.
What matters more is:
- whether the machine is cold or warm
- how the coffee tends to behave
- total roast time
- weight loss afterwards
- and whether the cup lands where I wanted it to
That remains the calmer way to read this machine.