General Notes; The Espresso Coffee; Storing The Coffee Beans; The Grinder-Dispenser And The Grinding Process - SM MACINADOSATORE SM92 Emploi Et Entretien

1. general notes

• The first part of this user's manual briefly explains the method of making espresso coffee, the modern
equipment used and the function of the grinder-dispenser in this delicate process.

1.1 The espresso coffee

Espresso is a coffee prepared with a particular brewing process, which makes it possible to make a very
concentrated, syrupy beverage of intense taste and aroma. The method of preparation of espresso consists
of extracting the substances contained in ground coffee by passing through it a flow of hot water under pres-
sure (about 9 bar) for 25 to 35 seconds. In this manner, the soluble substances (sugars and proteins) and the
insoluble materials (fats and colloids) in the coffee are "drawn out" into the cup, forming the characteristic
cream of real espresso. The preparation of espresso is a very delicate process; various factors affect the
success of this operation: the preservation of the coffee beans, the grinder-dispenser and the grinding pro-
cess, the preservation of the ground coffee, the espresso coffee machine itself, the changeable weather
conditions, and the care and attention of the operator in making the espresso coffee.

1.2 Storing the coffee beans

There are two varieties of coffee found in nature: the "arabica" variety and the "robusta" strain. Normally, the
roasted coffee used to make espresso contains a mixture of the two varieties, suitably blended in varying
percentages, taking into account the organoleptic characteristics of the individual components. The blend of
roasted coffee must be kept hermetically sealed inside its package. The roasted coffee beans contain within
them all the principles and characteristic aromas of the variety or the blend; these aromas fade rapidly when
the coffee beans come into contact with air, light and humidity.

1.3 The grinder-dispenser and the grinding process

The grinder-dispenser is a device designed to grind and dispense the coffee. To make a good espresso, the
coffee should be ground to particle sizes ranging from about 1 mm to a powder finer than 150 µm. Powdered
coffee offers a greater contact surface to water, allowing a greater extraction of soluble and insoluble sub-
stances. By varying the particle sizes of ground coffee, it is thus possible to modify the resistance offered
against the passage of water. If the ground coffee is made up of excessively coarse particles, the serving
time is too short, the water does not manage to extract all the qualities of the ground coffee, and the result-
ing espresso is light in colour, thin, bland and lacking the characteristic coffee aroma. when the ground cof-
fee is too fine, the espresso brewed is dark, burnt and cold; the serving time is too long and the water pas-
sage is too sluggish since the fine powder offers an excessive resistance to the water flow. The resulting
espresso is too strong.

1.4 Storing the ground coffee

Ground coffee is much more sensitive than coffee beans: the dispersion of aromatic substances takes place
very rapidly if it is kept in open containers and in moist environments. The coffee beans should be ground in
small quantities and the ground coffee should be used in the shortest time possible.

1.5 The espresso coffee machine

The espresso machine is a device that consists essentially of a boiler and a series of heat exchangers, in which
water is heated by an electric heating element or a gas burner. Water heated to a high temperature is made to flow
through the ground coffee placed in the filter cup and extracts its aromas. when this manual talks about espresso
coffee machines, reference will be made to both models with pump-operated distribution as well as those where
distribution is controlled by a hydraulic piston (referred to as lever-operated). La San Marco S.p.A. grinder-dispens-
ers are professional devices designed and built to be used with this type of espresso coffee machine.

1.6 Climatic conditions - Operator

As already mentioned, to make a good espresso it is essential that the coffee be ground to a proper particle
size. Ground coffee is very hygroscopic; in other words, it "senses" the moisture in the air and grinding should
therefore be modified to suit varying climatic conditions; a ground coffee with a high moisture content increas-
es the resistance to the passage of water. Other important factors in the making of espresso are the quantity
and compactness of the ground coffee inside the filter cup. These factors (moisture, quantity and coarseness
of the ground coffee, compactness) must be considered and weighed by the operator making the espresso.
For these reasons, the operator has a very important role in the espresso coffee-making process.
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