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Preparations
of Espresso Coffee
From a physical
point of view, the espresso coffee is a
beverage obtained by the percolation of
hot water under pressure through a layer
of roasted coffee, ground and pressed, in
the passage through the ground coffee, the
water pressure is exhausted and drink out
at atmospheric pressure. From a chemical
point of view it is solid-liquid
extraction where the solvent is hot water.
The method for preparing espresso coffee
from the other methods especially for the
use of high pressure and a temperature
that does not reach the boiling
point.
In addition, the
grinding of roasted coffee offers a
particularly fine resistance percolation
that allows the extraction of
water-soluble and lipophilic substances
that give the drink cup in unique features
in terms of cream, aroma, body and
aftertaste.
Of fundamental
importance is the freshness of the roasted
mixture, in practical terms, the maximum
fragrance of Espresso coffee obtained at
the opening of the sealed package of the
manufacturer, with the passing of days,
the exposure of the grains in the
environment, tends to the rancid oily
substances contained, resulting in less
production of cream and alteration of
taste.
A good rule might
be to keep the mixture into beans in the
jar closed, kept in a refrigerator and
ground on time. The cup has its
importance; The conical shape allows you
to see exactly how much fell into it, the
thick, or large mass, helps to maintain
relatively constant temperature of
Espresso coffee, of course the cup will be
warm before use, for this reason, the cups
in the local bars are positioned above the
machine.
For the
preparation of a good espresso using two
different types of machines:
1. The espresso
machine: It heats water purified at a
temperature between 90 ° and
94 °, the household, however,
uses non-carbonated water with low mineral
content. The water is passed to a very
high pressure (9-10 atmospheres) through a
filter containing ground coffee. The
filter can contain 6-7 grams (about 1 / 4
ounces) of finely ground coffee. The
quantity of coffee per cup reaches an
average of 20-35 ml (1 to 1 1 / 2 ounces
of liquid or about 1 / 8 of a cup). It
'important to make sure that the machine
reaches the specified temperature and
pressure levels and that the parties
through which the coffee flows into the
cup is already hot.
2. Moka: is
an ingenious device for pressure,
comprising 3 parts: a bottom container for
heating water, the center filter
containing the ground powder, and an upper
container receiving the coffee produced.
The bottom container is filled with tap
water or non-mineral, down to the level of
pressure valve. The filter is filled with
a good amount of ground coffee, as shown
in the image, not excessive, however, so
as not to compress too much dust. Use 6-7
grams (about 1 / 4 oz) per cup. The moka
is placed on a heat source medium (both
gas and electricity) so the water passes
slowly through the ground coffee. For each
cup content reaches 40-50 ml (thus leaving
it open about 1 / 4 of it). The coffee
must be stirring in order to make the
content uniform. The moka must never be
washed with detergent, but only with water
or with water and soda, and then left to
dry well.
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