SIMO KRISTIDHI is a four-time Norwegian Coffee Roasting Champion, runner-up in the 2022 World Coffee Roasting Championship and took first place in the 2012 World Coffee Roasting Challenge, the forerunner of today‘s World Coffee Roasting Championship. He entered the specialty coffee scene in 2004 when he started as a coffee roaster at Solberg & Hansen AS in Oslo Norway, one of the world‘s biggest and oldest specialty coffee roasteries. Simo has been working at the company ever since and has held various positions in the production chain: initially as a coffee roaster, then roastery manager, roast master and recently as a production manager. All those years his main goal was to learn as much as possible about coffee, but also to share knowledge with his fellow coffee roasters and colleagues.

We all know that the amount of data provided from the majority of roasters 20+ years ago was very limited. The only way to realize how to roast a coffee was by using the senses, the cupping table, and few equipment such a stopwatch and unstable (with limited range) exhaust temperature readings, often assisted by color measurement devices to determine the roasting level of the coffee beans.

At this stage roasters could communicate their roasting profiles based primarily on the color of the roast coffee, and the length of the roast and temperature level. Unfortunately, all those variables cannot describe what really happens during the process as more data need to be evaluated.

The so-called Third Wave of the specialty coffee scene brought with it a variety of new technologies and systems. Roasting machines became more technically sophisticated and were therefore able to provide reliable and meaningful data with regard to the roasting process. Terms such as logging systems, temperature sensors and development time formed the new terminology for coffee roasting. However, the rate of rise (RoR for short), i.e. the speed at which the bean temperature rises during the roasting process, also began to be discussed. In my experience, it is scientifically more reliable to use RoR as a critical value to determine a preferred roast profile or even to understand why the coffee tastes the way it does. I believe that RoR reveals our weaknesses as roasters in controlling a roast profile, while at the same time it is the best tool to predict what will happen next and whether we are on the right track. According to my roasting philosophy, the roasting process is based on three pillars: the color development, the roasting time and the RoR applied during the roasting time. All these three elements are directly linked.

When sharing profiles, it’s more common to talk about RoR than temperature values, because most of the roasting machines have something in common: the RoR values during the drying, the Maillard and the development phase tend to be similar on different roasters even though their temperature values are different. It’s easier to assess a roasting profile based on the RoR curve than the temperature curve. Often small temperature variations are difficult to detect, while those are very easy to see on a RoR curve. This makes it easier to share profiles.

As I mentioned earlier, the RoR exposes our weakness to maintain a stable curve because, it is the result of our actions (gas power, drum speed, batch to batch protocols etc.), but also the roaster’s ability to deliver the required energy and finally the bean pile’s ability to absorb this heat. Modern roasters create profiles based on temperature setpoints. Since my whole roasting philosophy is based on the RoR values, I hope one day we can design our roasting profiles based on RoR setpoints. This will make it easier to share, easier to understand and most important of all it will control the roasting process and increase the quality.