At the base of the preparation of an espresso there are some rules that barmen and apprentices must follow.

First of all, let's examine the word ESPRESSO. Espresso is the coffee that is prepared in that moment, or prepared in this moment for someone who is waiting.

Blend, Grinding, Machine For Espresso Coffee, Hand Or Mind Of The Operator.

These are the basis of the good coffee that we are going to examine.

Blend

The purposes of blends are essentially two:

The first one, purely commercial, is to adapt to a price scale a range of tastes that changes from customer to customer and from region to region.

The second one, purely technical, is to improve the quality of the product and maintain its constancy as time passes.

To obtain a good blend, it is necessary to know how to mix the taste, the aroma and the body of different coffees. The result will be a product with a certain taste, aroma and corpulence that can be constantly reproduced as time passes.

Usually, the more complex is the blend (from 5 to 8 components) the easier is to keep it constant, especially with the rotation of the crops, when some aged components loose some of their main characteristics, while the graft of new crops coffee with marked characteristics is better absorbed by other more aged coffees without altering the harmony of the blend.

Grinding

This process is fundamental to obtain an excellent drink: a wrong grinding can overheat the blend up to transform an excellent product to burnt powder. If the grinding is too thick, it becomes less soluble and the water flows away without completely extracting the aroma and the taste; if the grinding is too thin, the result will be an excessively strong infusion, sometimes with a burnt taste.
The grinder must therefore be adjusted in order to have an extraction of 25 - 30 seconds for a normal dose. If the time exceeds 30 seconds (over extracted coffee) the grinding must be loosened, if the grinding lasts less than 20 seconds (under extracted coffee) it must be tightened to reduce the water flow passing through the coffee. But pay attention, both the housing and the proportioning device must be periodically cleaned. Coffee incrustations on the shovels of the proportioning device cause lacks of balance to the doses and grease/oil residues cause a growth of rancidity. The check of the proportioning device must be periodically carried out trying at least ten doses and checking if the average corresponds to the base dose. One of the most common mistake is to use a small quantity of ground, with the risk of obtaining an over extracted coffee (minimum suggested dose: gr. 7). A suggestion is to keep in the proportioning device a small quantity of powder (the necessary quantity for 30 minutes work) in order to always have a fresh ground, avoiding to loose the aroma.

Pay attention to the wear and tear of the millstones.

For the grinders with flat millstones, these should be replaced after the grinding of approximately kg. 400 of coffee. For the grinders with conic-shaped millstones, they should be replaced after the grinding of approximately kg. 1200 of coffee.

Machines For Espresso Coffee

TEMPERATURE OF THE WATER FOR THE INFUSION
The temperature of the water for the infusion must be between 85°C and 92°C.

PRESSURE IN THE BOILER
In order to obtain the above mentioned temperature the pressure in the boiler must be:
Machines with lever: from 1,2 to 1,4 bars
Hydraulic machines or with continuous outflow: from 1,0 to 1,2 bars

PRESSURE OF THE CENTRIFUGAL PUMP
The normal value of the pressure must be 9 bars.

DOSE OF GROUND COFFEE
The minimum dose of ground coffee must be 6-7 grams.

GROUND PRESSING
A correct ground pressing in the filter must correspond to 20 - 25 kg.

INFUSION TIME
To reach 25/35 ml of liquid the infusion time must be between 25 and 35 seconds.

TEMPERATURE IN THE CUP
The temperature of the coffee in the cup immediately after the infusion must be around 65°C.

PRE-TREATMENT OF WATER
An extremely important element for the life of the machine and for a correct preparation of the espresso coffee is certainly the quality of water. If the used water comes from the city waterworks, it must be treated before the use, using carbon filters. As far as water hardness is concerned, this is partially eliminated by the resin softener.

Hand Or Mind Of The Operator

It is important to underline that the operator must be very careful to all the above mentioned preparation steps.

FILTERS MAINTENANCE
Pay attention to the filters holes that must not widen too much and the edge must not be too damaged by the continuous hits on the drawer.

FILTERS HOLDER
It is important to check the lips and remove from them the residues of dry coffee or other incrustations. The bed of the filter holder must be regularly cleaned and the incrustations must be removed.

SHOWER SCREEN
It is important to remember that some kinds of espresso machines have a double shower screen that must be cleaned and replaced when necessary.

GASKETS
The rubber gaskets must be frequently replaced in order to avoid the solids overflowing into the cup.

WATER SOFTENER
The resins must be periodically regenerated by dissolving in the softener 1 kg of coarse salt for each 1500 cups, that correspond to approximately 10 kg of roasted in beans.
The machines with continuous outflow must be often cleaned with the blind filter: a rubber disc must be introduced into the filter and once the filter holder is tightened, the machine must be started.