How do taste and aroma of coffee appear?

Green coffee beans have neither taste nor aroma. The true birth of coffee flavour happens when it is roasted.

When exposed to heat coffee beans acquire dark colour and change in their chemical composition, i.e. the substances contained in beans are transformed and the taste and aroma of coffee are thus formed.

Depending on the temperature and duration there are three major types of roast:

Light (weak or Viennese) roast gives to coffee beans light brown color; light acidity can be tasted in brewed coffee.
Medium (French) roast is the most common degree of roast. Coffee beans roasted this way have beautiful brown color and rich full taste.
Dark (strong or Italian) roast gives to the beans deep dark brown colour. Coffee brewed from dark roasted beans has rich flavour without much acidity.

Initial processing of coffee beans is carried out at factories and in large warehouses where many operations aimed at sorting and selection of coffee beans are performed.