We thought, we simply cannot pass up the opportunity to share Valerian Hrala from Coffee Is Me and Coffee Courses‘ article on Rate of Rise (RoR)

Did you know that coffee roasters can predict the future? Yes, it is true; the only thing you have to learn is the correlation between the elements of the roast profile mentioned below and you will be able to predict the future… of your roasting coffee… a few minutes ahead.

Looking at a roast profile you can see a horizontal axis indicating the time, and a vertical axis for the temperature. To predict the future, you only need to record the temperature (bean temperature) but for that magic power, you will also need to record it every 30 to 60 seconds, depending on the system, and calculate how fast the temperature is rising. This is called the rate of rise (RoR) and you can think of it like the tachometer in your car, telling you how fast you’re going.

Telling the future of your roasting coffee needs more accuracy. There are a lot of chemical reactions happening in the coffee during the roasting process and they occur at different speeds. To determine your acceleration, you need to know the so-called exhaust or environmental temperature, the temperature in the drum of the coffee roaster.

Roasting coffee beans brings them to the environmental temperature in the drum. If that temperature is very high, your coffee beans will try to reach that temperature faster. If you use a lower temperature, this will happen more slowly. It sounds obvious, but many roasters do not think about this correlation during roasting, and miss an important datapoint for predicting the future.

When you look at the roast profile you will see bean temperature rising faster (bigger RoR) at the points where the difference between the environmental temperature and the bean temperature is larger. It also means that you have less control over the roasting process. Why?

When you increase the heat, there will be a delayed reaction to the environmental temperature and an even later response in the bean temperature. If you do not apply enough heat (marked as heat output on the roast profile), the reaction will be too slow and you will be baking rather than roasting your coffee. If you apply too much heat, the environmental temperature will rise too high and good luck bringing it back.

So if you think about these elements of the roast profile, you will be able to control your speed and get exactly where you want with your coffee. It all might sound a bit scary in the beginning, but if you start to think about these terms and put them into correlation you will see it all makes sense.

Master this way of thinking and be proud that you are the only species that can predict the future!
Make sure you check the next email. I might admit that I am a liar. Or not. Future will tell.|

Until then, drink only good coffee
Valerian