This is one of the most delicate stages in preparation of an espresso coffee and calls for care and experience. It serves to increase the surface in contact with the water and to thus extract the greatest number possible of the substances it contains. Every blend has its own correct grain size, the result of trial and error. Furthermore, ideal grinding, which permits optimum passage of the water through the pressed coffee, must also take ambient humidity into consideration. In professional sectors, this task is today entrusted to grinder-dispensers that in addition to pulverising the beans also set the correct amount of coffee needed for the espresso machine.
The espresso machine
This meets the need to prepare coffee in the quickest time possible without leaving dregs in the cup. It works on the basic principle of the passage of water at a high temperature and high pressure through a given amount of ground coffee, coming out the other side full of taste and aroma. At this point, and in part due to the skill of the barperson, a metamorphosis occurs, resulting in the well-known fragrant elixir with its hazelnut colour, dense body and rich aroma that culminates in the perfect three millimetres of light cream on its surface.
The touch of the barperson
7 g of powder, 9 bars of pressure, 90° of water temperature, 25 seconds for extraction and 25 ml of liquid in the cup: this is the magic formula that distinguishes the best espresso. But the machine alone is not enough: the experience and talent of the barperson are vital. His or her responsibilities include choice of the blend and management of storage, correct pressing (the equivalent of a firm handshake), adequate water treatment, attention to minimum details, maintenance and control of equipment.