The basis of a good espresso coffee are the coffee beans which must be of excellent quality
All the most sophisticated technique and the best barista will never be able to extract a
good espresso from a bad coffee. Blend or single origin, the
coffee must be of
excellent quality , pleasant, sweet, fragrant, aromatic and leave a
pleasant and lasting aftertaste . Let's remember that, after drinking a good coffee, we must feel the desire to taste another one. Furthermore, within the limits of local habits and tastes,
the coffee beans must be roasted at the right point , because if it is
too dark it will be more
bitter , if it
is too light it will be excessively
acidic .
Preservation of roasted coffee
Coffee beans keep for a long time in the original sealed package, bag or jar, but once the package is opened, the product deteriorates rapidly. To best preserve it, after use it should be placed in an
airtight container and stored in
a cool, dry place . The same technique can be adopted at home to preserve the ground coffee, but in any case, even with this warning, the ground coffee will lose most of its aromas in a few days due to its oxidation. In fact,
ground coffee is about fifty times more perishable than coffee beans . In fact, the surface of the coffee exposed to oxidation from the atmosphere increases by so much with the grinding. The barista should never store overnight ground coffee in the grinder.
The cream
It is a foam, i.e. a dispersion of gas (air and carbon dioxide) in a liquid; the liquid part responsible for its formation contains oils emulsified in water.
The color of the cream, in a perfect espresso, is more or less dark hazelnut . A
crema that is too
light indicates
underextraction , caused by an insufficient quantity of coffee,
too coarse a grind , or
too low a water temperature . On the other hand, a tendency to
black , accompanied by a
white button , indicates
overextraction .
The consistency of the
espresso cream must be
two or
three millimetres , with a tight mesh.
Under-extracted or over-extracted coffees tend to lack crema . The duration of the cream is due to the same details that determine the consistency. The
ideal permanence time on the surface must be at least
two or three minutes , with no openings in the central part.
Without crema, an espresso coffee cannot be classified as such , showing a watery, inconsistent body, more or less pronounced bitter tones, a weak aroma and poor persistence.
The aroma, good or bad, of coffee depends on over a thousand different molecules which are formed from the birth of the bean on the plant and subsequently transformed during the
manufacturing and conservation processes .
The
intensity of the
aroma of the espresso is mainly due to the
presence of the crema which acts as a trap for the volatile substances, preventing them from escaping immediately after the preparation of the drink. An optimal cup of espresso coffee must therefore have a
high body , a
persistent aftertaste , an
intense taste and aroma and a
compact crema ; unlike filter coffee, which is consumed as a drink, espresso is mainly used as a kind of invigorating elixir.
The espresso machine
In the modern automatic espresso machine, the heart is made up of the boiler in which the water is heated. It should be remembered that the water in the boiler is not used to make coffee, but in most models it will indirectly heat the water with which we will extract the espresso coffee. Steam is formed in the upper part of the boiler which, via a nozzle on the machine, will be used to heat the milk and other liquids. The water for the coffee, pushed by a pump at a pressure of 9 bars (atmospheres), passes into a heat exchanger inside the boiler where it is heated and kept at the right temperature. To avoid drops in water temperature, the group to which the filter holder is attached is heated in turn with a water recirculation system.
The utmost attention must be paid to some components of the machine.
Filters : the holes must not be blocked by coffee residues and they must not be consumed.
Filter holder : it is necessary to check carefully that the coffee outlet spout is clean.
Showers : even in the showers as in the filters there are countless holes that must be cleaned constantly.
Gaskets : they must be changed periodically to avoid leaks and therefore that part of the coffee powder can fall into the cup, thus creating the classic defect of the grounds in the cups.
The Grinder
The bar grinder is made up of two superimposed flat millstones, whose distance is adjustable to choose the right thickness of the powder. The grinding must also be adjusted several times a day, as a consequence of the variation in atmospheric humidity, especially in areas with a variable climate:
humid weather requires
coarser coffee , otherwise percolation is slow and difficult and the product will be over-extracted;
dry weather requires
finer ground coffee , otherwise extraction will "run" and the coffee will be under-extracted and light. It is advisable to always grind a little coffee at a time, so that the product is always fresh.
The correct preparation of the espresso
To have a good espresso, you need at least
7 grams of blend .
Once the filter is filled from the dispenser, the coffee is pressed with a force of 10-20 kilos. In principle, the good operator will adjust by pressing the coffee in order to compensate for any small differences in grinding. Before hooking the filter holder to the machine, the
edge of the filter holder must be
cleaned , because coffee residues could limit the closure (with consequent loss of pressure) and form deposits on the gasket, which will deteriorate more quickly.
The
extraction time varies between
20 seconds for a small coffee and
40 for a long coffee. The quantity in the cup will therefore be between 20 and 40 ml.
The coffee must come out of the group in a so-called "mouse tail" shape, flowing on a regular basis.
I recommend the cup must be very hot, but woe to you if it burns the customer's lips.
To prepare your perfect espresso, choose the best Mokito blends, discover them
here !
