Coffee Roasting Light Roasts
@Marks
Posted in Coffee Roasting
Light Roasts
I'm roasting on a 2 kg digital, and using standard profiles (charging at 425F), with the 4 or 5 gas changes I see on most of Bryant's roasts. But with first crack occurring at around 389F, and a 15% DTR, the beans drop on the darker side (often 55 on the Agtron scale using a Difluid). Any suggestions on how to adjust to get a medium light roast (around 70 Agtron)?
Hi Marks,
To obtain a lighter roast, you will need to make lower gas adjustments before first crack. I have included two reference profiles below to help illustrate this. Both batches are 1KG charges, and also roasted on our MCR-2D.
Light roast: The gas pressure 1:30 before first crack was adjusted down to 0.4kPa. This decreases the speed of the roast and can keep us at a lower finish temp at the same DTR % you reference.
Medium roast: The gas pressure ~1:10 before first crack was adjusted down to 0.6kPa. This keeps slightly more energy in the roast than our light roast gas decrease, therefore leading to a higher finish temp than the light roast at the same DTR % you reference.
Hope this helps give you some ideas. Happy roasting!
- Bryant
On Bryant's last four roasts (RP-7128, 7130, 7132 and 7133), all with 1 kg charges on a 2 kg machine, the drop temperatures were between 391.8 and 405.9 F. What do you see as the correlation between these drop temperatures and measured roast color? Do you use these drop temps as markers of the roast color you are trying to achieve?
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