How High Should Your RoR Be?
You’ll often hear people discuss a high or low RoR. And simply put, a higher RoR indicates that your roast is progressing quicker; a lower one means that it’s progressing slower.
Jen tells me that you don’t want your RoR to drop too low because then you risk reaching the stalling point. A stalled roast happens when the RoR becomes so low that the machine doesn’t want to recover, and the temperature remains the same. This can lead to “baked coffee”, a defect that creates a flat, doughy flavour. In this situation, the coffee’s aromatic compounds won’t be developed.
However, that doesn’t mean a high RoR is best. Your goal should be to control your RoR with precision. And as you learn how to do this, you will find you are able to accentuate different flavours in your coffee. For example, a higher RoR – especially towards the beginning of the roast – can accentuate acidity. Willem Boot of Boot Coffee and Finca La Mula also states that a lower RoR can help modulate sweetness.
The right RoR will depend on many factors: the coffee, the desired profile, the stage in the roast, and more.