Have you ever heard of RoR?

It is not RUR, as many might think, as this abbreviation of Čapek's is far more familiar. But RoR, Rate of Rise. Let's take a look at it.

RoR is a valuable tool for more precisely controlling the different roasting stages in a coffee bean. It makes it easier to avoid mistakes and get the best flavour from the bean. If you can read the data obtained from the RoR curve, you can better and predictably control the roasting process and shorten some stages and more desirably lengthen others, such as the Maillard reaction in the bean.

To measure the RoR during the roasting process, you need several temperature probes to measure the temperature inside the drum and inside the beans and stem. With the data collected, powerful software (such as Cropster, meets all the expectations of the modern roaster who wants to use thelatest technologyfor his profession capable of performing sophisticated calculations in real time and thus influencing the quality of roasting "now and here". It's quite a science, and so unless you understand exactly the data and outputs that the program offers you will have very little use for RoR .

If you can read the data obtained from the RoR curve, you can better and predictably control the roasting process and shorten some stages and more desirably lengthen others, such as the Maillard reaction in the grain.

What is RoR?

In full Rate of Rase. It is a measurement of the rate of temperature rise in the coffee bean and drum over a period of time. The higher the RoR, the faster the roast progresses and conversely the lower the RoR, the slower the roast. TheRoR must never drop to too low values. If very low values are reached, the roasting process may reach a standstill (deadlock) and it may happen that the roasting process stops and does not develop further, due to low energy, when the temperature cannot be increased. This leads to roasted coffee that has a flat and undeveloped flavour. RoR is a great tool to brew the best possible coffee elegantly and without complications. The prerequisite is to master the interpretation of the data provided by the RoR curve and the manipulation of the temperature and thus the RoR adjustment.


Experienced roasters only need their own senses to estimate the bean temperature, which is a good indicator of the different stages of roasting. If we want to do this with new technologies, it is important to measure the temperature of the beans with accurate thermometers over time. Properly measured, the units should be clean and in well-chosen places in the drum.


It is not a good idea to compare data with other roasters for any purpose other than study. Each roaster, even from the same manufacturer, is different and roasts differently. Therefore, the data cannot be identical. Each roasting plant establishes its own database of roasting programmes according to the RoR measurements and bases its roasting profile on the individual characteristics of the coffee, the roaster and the RoR values. Between these points, the RoR can be measured and used as a control between roasting processes. The RoR curve tells us whether the roasting process speeds up or slows down depending on the temperature, it is an indicator of the temperature curve and tells the roaster what will happen next and how to adjust accordingly.

For example, if you take a RoR of 5 at 30 sec. It means that the temperature of the beans will increase by 5℃ every 30 sec. It is important to keep track of a few critical moments, clues or if you want checkpoints of the whole roasting process, which perfectly predict the next development. The maximum RoR (observable as yellowing of the grains), the first crack, and the end of RoR (caramelization). The maximum phase of RuR occurs after the turning point. The temperature of the grains after being thrown into the drum has levelled off and started to rise. The next significant temperature change occurs at the first crack. Under no circumstances should you allow large temperature fluctuations. The end of the RoR naturally occurs at the end of the roasting process.


There are a few rules for RoR that are good to follow. It's not a good idea to increase or decrease RoR mindlessly, as it can lead to roasted or undercooked coffee. Both with an unpleasant taste lacking the finer undertones. If you need to adjust the temperature and thus the RoR, the drying or yellowing stage provides plenty of scope. Watch for a time of about 2 minutes before the first crack. At this point, any decisions regarding temperature adjustment can have far-reaching consequences, as we first suggested. A perfect roast should have a downward trend in the RoR curve.

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