The roasting process consists of the following phases
All phases at a glance
Drying the coffee beans
Green coffee contains up to 11 percent water, which is distributed in the bean and must be evaporated before roasting. Therefore, in the first phase, the roaster is heated and energy is supplied to the beans until the water evaporates (at around 20 - 130°C). This phase is very important and must be done in such a way that the entire bean is free from water; otherwise, it will roast less inside and acquire an unpleasant, grassy taste afterwards.
The Maillard Reaction
From approx. 130°C, the roasting process begins. The beans slowly turn yellow and change colour to a beautiful caramel-like brown. Chemical processes take place in the bean, especially the so-called Maillard reaction. The beans noticeably increase in size, and the fine skins dissolve. At the Gene Roaster, these skins are automatically blown away by the airflow, while with the Hottop Roaster, you should turn on the ventilation at this point to prevent the skins from remaining between the beans and burning.
First Crack / the first crack
The big moment for you as a roaster. In the bean, carbon dioxide and steam build up pressure to the point where the bean bursts. You can recognize this by a cracking sound (first crack) or crackling. From now on, it's your time as a roast master, as the beans are now drinkable, and you determine how dark your roast will be by the duration. Now you need to apply some heat again to allow the beans to develop nicely.
Second Crack / the second crack
If you roast for filter coffee, you have probably completed the roasting before the second crack. For espresso or darker roasts, the second crack is an important moment. It is a second popping of the bean; however, the cracking sounds are slightly finer than the first crack. From now on, oils emerge from the bean, which you can recognize by the slightly shiny surface. The acids and characteristic flavour notes of the coffee are now only very weakly pronounced, but the beans now have more roasting flavour and become noticeably more bitter.
Cooling the roasted beans
This is also a very important step in the roasting process, as the beans need to be cooled quickly to stop reactions and prevent further roasting of the coffee. With the Hottop coffee roaster, this is easily done at the push of a button - the beans are rapidly cooled. The Gene Café coffee roaster lacks such a cooling device, so you can either build your own cooling system following instructions from the internet or cool them, for example, with a sieve over a fan.
Coffee Storage
After roasting, carbon dioxide still escapes from the beans. This directly affects the taste right after roasting. Therefore, you should wait a few days before grinding and drinking the coffee. In our experience, the coffee is at its best between the third and tenth day after roasting. After that, the essential oils that give coffee its flavour have dissipated, resulting in a noticeably duller taste. It is best to store the beans in a bag with a valve (also available in our shop) or in a container with a valve, allowing carbon dioxide to escape while preventing oxygen from entering.
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