Coffee roasting, what happens during this process?
Coffee Roasting is one of the most interesting aspects of coffee transformation. A green bean, almost without flavour and aroma except for a few vegetable notes, undergoes a complete transformation when exposed to heat.
The smell of freshly roasted coffee is so sophisticated that all attempts to manufacture a realistic synthetic imitation of this smell have failed.
How coffee roasting takes place
The beans are loaded into the roasting machine and heated to temperatures between 200 degrees Celsius. The duration of the process depends on the type of coffee and the desired degree of roast.
In general, three main phases can be distinguished: the drying phase, the actual roasting phase and the cooling phase. During the first phase, the beans lose their initial moisture and take on a light yellow colour. In the actual roasting phase, the chemical reactions take place that give the coffee its organoleptic characteristics. The cooling step serves to stop the chemical reactions and stabilise the coffee.
The different degrees of roasting and their effects on coffee flavour
The different degrees of roasting determine the final taste of the coffee. Five roasting grades can be distinguished: light, medium light, medium, medium dark and dark.
Lightly roasted coffee is characterised by a mild flavour and a fruity aroma. Medium roasted coffee has a stronger flavour and a hazelnut aroma. Dark-roasted coffee has a stronger flavour and a roasted bread and chocolate aroma.
It is important to notice that roasting should not only be considered a mechanical process, but also an art. Indeed, the roaster must have the experience and sensitivity to create the perfect balance between aroma, taste and bitterness of the coffee. Furthermore, the quality of the green coffee beans plays an important role in roasting. Superior quality beans will result in quality coffee.