Coffee is not only a typical Italian beverage, it is also a social moment, a cultural offering, a relaxing break in overly busy days. And the easiest, cheapest and fastest way to make, or offer, a cup of coffee is with an aluminum contraption invented in 1933.
The Moka Express is invented between the two world wars by Alfonso Bialetti of Omegna, Piedmont, and began to be produced on an industrial scale in 1946. Since then it has quietly and modestly invaded the homes of all Italians. Even today as new and more trendy ways of making coffee have spread, the mocha remains indispensable, if only to prepare an emergency cup when the other, far more complex systems are out of service.
Yet the physical principles that determine the release of the precious dark drink have remained A mystery for over sixty years, in fact the first scientific analysis of Moka's operation was published in an authoritative scientific journal only in 2007.
How does the mocha work?
Contrary to what many people think, water is not solely responsible for making coffee; the air trapped between the filter and the water also plays its considerable part.
Under the effect of the flame of the stove, and the consequent heating of the metal, following the physical laws of gases, air increases its volume and thus its pressure, beginning to push the water underneath. The only place the water can go is upward, into the filter, it then begins its journey by going to fill the filter bowl and beginning to dissolve the coffee powder in it.
Further increasing the temperature evaporation of the liquid is triggered at this point, and driven by steam pressure it begins to rise toward the upper chamber of the Moka pot, escaping from the spout. Our cup is now almost ready and its aroma has already invaded the kitchen.
Before pouring the dark liquid into the cup, it is best to stir the coffee with a teaspoon. This is because the first coffee to come out is colder and also more acidic and aromatic than the last, which is hotter and more bitter. Let's look at the suggestions in detail To achieve great-tasting coffee.
Water
The water must not exceed the level of the safety valve, because some air must be left under the filter. The water used should not be too hard, that is, have a lot of salts. If the tap water in your area leaves a lot of limestone, then use bottled water, choosing one with low fixed residue values.
Coffee
Coffee suitable for Moka is coffee ground slightly coarser than for the espresso machine. It is necessary to fill the filter completely but without pressing with the teaspoon or creating mounds. This is because once the Moka is closed, the coffee in the filter would be over-pressed and make it more difficult for the water to rise up. Poking holes with a toothpick is also forbidden, for the opposite reason: the water would rise too quickly.
The flame
The Moka pot requires a low flame and a long boiling time, so the liquid as it rises takes maximum substances from the coffee powder. When the coffee pot begins to mumble, turn off the flame.
Source: Bressanini-lesciences-blog
