I'll be roasting some beans from PNG (Papua New Guinea)
These are Arabicas from the Central Highlands in Simbu provence.
1500m +
For a PNG Arabica from Simbu Province, the bean is typically a washed, high-altitude coffee with bright acidity, medium body, and floral/citrus notes. The roast profile can vary depending on your desired flavor balance.
Different roast levels will give different flavours.
Light roast – highlight floral, tea-like, and citrus notes.
Medium roast – balance body and acidity, bring out caramel sweetness.
Medium-dark roast – reduce acidity, emphasize chocolate and nutty tones.
This is my planned roast.
To compensate for any inaccuracy in my roaster's temp I'll charge it at 200C and aim for a turning point closer to 100-110C. ... basically adding 10C to each of the above temps.
Here is my planned roast curve.
I'm using a simple thermometer and probe.
It can't measure the bean temp so I'll need to make some educated guesses.
Below is my plan of attack.
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Charge temp
For a 200g drum roast of PNG Arabica (Simbu Province) targeting a medium roast, a good charge temperature is typically between 185 °C and 195 °C (365–385 °F), depending on the roaster’s thermal momentum and airflow setup.
Here’s a breakdown for context:
🔹 185 °C (365 °F) → gentler start; longer Maillard phase, more sweetness, softer acidity.
🔹 190 °C (374 °F) → balanced approach; good development and clarity for PNG profiles.
🔹 195 °C (383 °F) → faster roast, slightly more body and caramelization, reduced floral notes.
In the future when I get a better roaster, I'll be more accurate.
For the moment, this is just a learning exercise.
For a small 200 g batch, heat transfer is quick — so I’m starting around 188–190 °C, &
watching for a turning point around 1:30–1:45.
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Turning point
The turning point marks when the bean temperature bottoms out after the initial heat absorption.
Since 200 g is a small batch, heat transfer is fast — Im trying to avoid charging too hot, or the turning point might happen too soon (<1:20), causing a “front-loaded” roast with harsh acidity.
I'm aiming for a smooth, declining Rate of Rise (RoR) afterward — aiming for a steady climb through drying (~8 min total before first crack).
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The roast turned out as follows:
Start weight: 200g
End weight : 187.7
Water loss: 12.3.... 6.15%
It falls into the extremely light roast category.
I think the readings I'm getting from my probe don't accurately give me an idea of what the bean temp is.
It's much lower than the readings on the probe.
I think I'll add maybe 15C to the temp next roast
Time Temp
0 .... 200c charge
1.30 169 TP
2 163
2.30 153
3.00 148
3.30 144
4.00 143
4.30 146
5.00 150.... end of yellowing phase
5.30 155
6.00 163
6.30 170
7.00 175
7.30 179
8.00 181 ... end of browning phase
8.30 184 FC. start development phase
9.00 190
9.30 196
10.00 202
10.30 END roast temp 207C
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