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Moka

Moka: how it is made and how it works

Moka, also called Moka express, is a device for preparing coffee as a drink; it was invented in 1933 by Alfonso Bialetti and has literally revolutionized the domestic coffee preparation process, sending retired coffins and Neapolitans. The success of the Bialetti mocha was such that it was produced in 200 million pieces, ending up in the homes of nine out of ten Italians. The term Moka recalls the name of the Yemeni port which for several centuries represented the main supply route for coffee harvested in its lands of origin (Horn of Africa).

The moka essentially consists of three parts:

  1. the boiler, containing the water to be brought to a boil;
  2. the mechanical filter, to be filled with finely ground coffee;
  3. and the upper part, which collects the drink.

The operating principle is quite intuitive. First fill the lower part (boiler) with water, fill the filter with coffee, place it in the appropriate space and screw the upper compartment onto the lower compartment. At this point the moka is placed on a heat source and it waits for the water to come up through the filter, turning into coffee and gathering in the upper part.

But how can we explain this ascent from the physical point of view?

When the water comes to a boil the steam produced produces a certain pressure against the walls of the boiler and against the water; the latter is thus pushed downwards and, as soon as the force exerted by the steam overcomes that of gravity, it finds free rein, ascending through the funnel of the filter. During this ascent. the water passes through the filter containing the coffee, extracting caffeine and various aromatic substances, and turning into the drink that we all know; the further ascent causes the freshly formed coffee to collect in the upper part of the mocha, passing through a cannula called "fireplace".

The ascent stops when the water level in the boiler falls below the level of entry into the funnel spout.

In addition to the three main components, the moka is also equipped with a simple spring valve, calibrated in such a way as to avoid excessive pressure increases, which could cause the moka to explode and which are generally due to obstructive phenomena (for example due to a excessive pressing of the coffee powder in the filter); a gasket, finally, ensures the safety of the screwing.

How to make coffee with mocha

  • Choose a good brand of coffee, suited to your preferences in terms of flavor and caffeine content; important conservation, which must take place in hermetically sealed containers, since the dust tends to absorb odors altering its aroma.
  • Use fresh water; tap water may work, as long as it does not have a too strong taste (for example due to the excessive presence of chlorine or limestone); in this case it is better to use a normal bottled mineral water.
  • Fill the boiler with water until it reaches the level of the safety valve, but without going beyond it.
  • Fill the filter generously with the ground coffee, without pressing: just adjust it by tapping the filter on a flat surface or by forming a small bun with the spoon; the recommended dose is 6-7 grams per cup: depending on your preference you will get a more or less "strong" drink.
  • Close the machine vigorously and place it on the fire; to allow greater extraction of the aromatic components of the coffee, the flame must not be too high, but tendentially low.
  • When the coffee begins to come out, immediately lift the lid to prevent the steam from condensing by falling into the collector and altering the taste of the drink.
  • Just before the coffee has completely come out, remove the moka from the heat to prevent it from boiling, giving the drink an unpleasant, burnt aroma.
  • Before serving the coffee, which should be consumed hot to fully enjoy its taste and aroma, it is good to mix it, because the first part is more concentrated than the second.
  • After use, carefully clean the moka - dismantled in its three components - simply with warm water; particular care in cleaning the filter, to prevent the coffee residues from turning into a receptacle of germs and molds; in this regard - to facilitate cleaning operations - there are special brushes.
  • When the moka is new or has been inactive for a long time, before using it it is advisable to make it work with water and little coffee. In this way a thin layer of greasy residues is deposited in its internal walls, which prevents direct contact between the coffee and the mocha aluminum walls (which could give it a metallic taste); this also explains the advice, given a few lines ago, to wash the moka with simple warm water, without ever using soaps and detergents.

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