Steps to roast coffee beans professionally: 1- Thermal shock: the green coffee is immersed in the roaster drum heated between 160 and 220°C. The coffee then undergoes a thermal shock of 150 to 200°C. 2- Drying: from this low point, the heat transfer is reversed and the actual roasting begins. 3- The rise in temperature: drying and cooking of the coffee follow their course and the first compounds are formed under the effect of the Maillard reaction, common to many products. 4- Caramelization: from around 170°C, caramelization begins in turn. The sugars are broken down. 5- The aromatic maximum: between 180 and 200 °C, the aromatic maximum is revealed. The grains are then brown. 6- The first crack: it occurs around 205 °C. The grains, which have now lost all their water, suddenly release part of their carbon dioxide. 7- The heart of the roasting process (development time): the crucial phase for the roaster begins, that of development. 8- Cooling: the beans are finally taken out of the drum and cooled rapidly (> 3 to 5 minutes) .