In theory, the process is simple: the coffee grain is roasted to modify its structure and to unleash the aromatic oils that make up its flavor. The same process is done with beans for chocolate, malt for beer, walnuts, hazelnuts and other seeds used in cooking.
In practice, coffee roasting is a delicate, extremely precise operation that depends on temperature, time, and volume, but also on the roaster’s expertise. Three different kinds of roasting can be distinguished: light roasting for fruitiness and freshness, medium roasting for sweeter, more gourmand flavors, and dark roasting if toasted notes and bitterness are desired.
The art of roasting is to find the right balance according to the desired taste result.