The Moka Express or Espresso Pot, is a slightly
more complicated version of the Vacuum System and is much favoured
and widely used in Italy.
The standard model consists
of an aluminium body in two halves, which screw together and is
fitted with a bakelite (heatproof) handle. This coffee brewing
device was originally created by Alfonso Bialetti in 1933 and has
since become a design icon.
The design has remained virtually unaltered to this day and his
company, Bialetti Industrie S.p.A., is still the major manufacturer
of the product. It is recognised as an essential part of an Italian
kitchen.
The brewing system operates by firstly pouring fresh water into
the bottom half of the pot. A metal filter with tiny holes is
inserted on to the base. Fine ground coffee is placed and tamped
(compressed) in the filter, then the upper part (which has a open
tube through the middle) is tightly screwed on the base.
By placing the pot on a heat source, the water in the bottom of the
unit is heated until pressure forces the water up through the
coffee in the filter, through the centre tube of the upper half,
and into the top half which becomes filled with the brewed
coffee.
There is an audible bubbling and hissing sound when the process has
completed and the unit is then removed from the heat source and the
coffee is ready to serve. The top can be unscrewed from the lower
half for ease of use. There is a simple pressure valve fitted to
the system to ensure safe operation.