What is Rate of Rise?
Rate of Rise (RoR) measures how quickly the temperature of coffee beans increases during roasting. It’s usually shown in degrees per minute, though some roasters measure it in 30-second increments. For example, a RoR of 5°C per 30 seconds means the bean temperature is rising at that rate throughout that period.
RoR is tracked using temperature probes inside the roaster’s drum and visualised on a graph. It provides a more responsive readout than the bean temperature curve, helping roasters make quick adjustments to hit their desired profile.
A typical roast shows a gradually declining RoR – fast at the start as beans absorb heat, then slowing down towards the end. Spikes on the RoR curve often mean beans are taking on heat too quickly, which can lead to scorching or baked flavours.
Why does RoR matter?
RoR offers early insight into how the roast is progressing. Because it reacts faster than bean temperature, it helps roasters stay ahead of the curve and steer the roast more precisely.
Key stages of RoR:
- Top RoR: The peak rate after the turning point, when heat absorption is at its highest.
- Crack RoR: The rate of rise during first crack – critical for flavour development.
- End RoR: The final RoR before finishing the roast. Lowering it carefully here helps avoid overdevelopment, especially since beans are drier and more brittle at this point.