What is ROR in roasting? How to adjust the heating rate?

ROR, the abbreviation of Rate Of Rise, is simply the rate of temperature rise. It is an important indicator for us to judge the speed of roasting during the roasting process. ROR generally records the temperature rise rate per minute, for example, 4 minutes, 148 degrees; 5 minutes, 158 degrees, then ROR is 158-148=10 degrees.

1. ROR can be used to judge the rhythm of roasting during the roasting process. If the ROR value is too high or too low, it becomes an indicator for us to adjust the firepower. If the ROR is too high, the roasting rhythm will be too fast, and the overall roasting time will be shortened; if the ROR is too low, the roasting rhythm will be delayed, and the roasting time will be too long.

2. The proposal and popularization of ROR should be the author of “Guide to Roasting Coffee”, Scott Rao. According to Scott Rao, ROR should show a smaller and smaller trend in the ideal roasting process. That is, the temperature difference will become smaller and smaller.

3. Connecting the ROR becomes a smooth curve. As mentioned in the previous article, it gradually decreases during the ideal roasting process. And if the ROR drops rapidly, or rises in the middle and late stages, it may affect the flavor of the coffee.

4. The value of ROR will reach the maximum in about 3 minutes, and the heating rate is relatively slow when it first enters the first explosion.

5. The value of ROR does not affect the change in the taste of coffee beans, but only gives us a prediction of the state of the beans.

The temperature in the boiler drops momentarily when green beans are put in. Soon the temperature turned into a rising curve again, and this place was called the “Turning Point”. After Turning Point, there will be a maximum temperature increase rate, and this rate is called “RoR (Rate of Rise)”. Simply put, RoR is the gradient of temperature change.

The interval from the first explosion to the end is called “Development Time”. The recent trend is to analyze the roasting by the ratio of the entire roasting time to the development time. The temperature difference between green beans and air can also be confirmed through the graph. This data is a measure of how much convection heat is used in roasting. As can be seen in the graph below, the temperature difference at the Turning Point, the first explosion, and the end can be calculated.