How To Extract An Excellent Espresso

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Espresso should be creamy, dense, aromatic and prepared with an industrial machine which modern technologies has made perfect; yet making a good espresso is still a craft which few people have.
Watching a barman who, with quick and confident gestures, prepare an espresso behind the other, can lead to think that it is an easy thing to do, practically within the capacity of everyone.
Instead, behind those almost mechanical gestures there is knowledge, study, skill and a lot of precision, but also cleanliness , accuracy, scrupulous care for the product and the machine designed to produce it.
In fact, many are the factors which affect the success of a good espresso.

THE BLEND
All the most sophisticated techinque and an experienced barman will not be able to extract a good espresso from a bad blend.
Blend or single origin, coffe should be good, that is pleasant, sweet, fragrant, aromatic and leave a pleasant and lasting aftertaste.
Let us remember that always, after drinking a good coffee, we should feel the desire to drink another one. In the limit of local habits and taste then, coffee beans shall be roasted to perfection, because if they are too dark they will be bitter, if too much light they will be too acid.

STORAGE
Coffee beans lasts a long time in the original package, sack or jar but, once you open it, the product deteriorates rapidly. To preserve in the best way, after using it you shoul put it in a watertight container and preserve in the fridge.
The same tecnique can be used at home to preserve ground coffee, but in every case also with this warning, ground coffee is about 50 times more perishable than coffee beans. So much in fact the grinding increases the coffee surface exposed to the atmosphere oxidation.
Barmans should never preserve ground coffee in the hopper more than an hour.

THE PROFESSIONAL COFFEE GRINDER HOPPER
THE COFFEE MILL

The common coffe mill for cafe is made by 2 overlapping flat grindstones, whose distance is adjustable in order to choose the right thickness of the powder. The grinding shall be adjusted several times a day, in consequence of the variation in the atmospheric humidity, especially in areas with variable climate: a high humidity requires a coarser grinding, otherwise percolation is slower and stunted and the product will be over extracted; the lack of moisture requires a finer grinding. It is good to grind a little at a time, so that the product is always fresh: it should cover just the fins of the hopper, besides, the coffee grinder with flat grindstones spin at high speed and for a long use will overheat the coffee, giving it a disagrable taste of smoke and burnt. The machines must be replaced approximately every 400 pounds of coffee. In case of very clear roasted coffee the wear and tear of the machines is more rapid and therefore must be replaced more often.

THE HOPPER
The volumetric hopper does not weigh coffee, but it dispenses a certain volume of it, which must be arranged and checked with great care and some frequency.
The ideal quantity should be 7 gr per cup, 14 gr per two cups.
In the absence of sensitive scales, the hopper calibration is made by weighing ten bars and adjusting about seven grammes.
The cleaning of the machine is very important, because coffee residues may go rancid and spoil the taste of the product.

THE MACHINE
In the modern automatic espresso machine the heart is a boiler in which water is heated. It is good to remember that the water in the boiler is not used to make the coffee, instead, it is delivered from the apposite tap, and it will be used for tea or other uses. In the upper part of the boiler steam is formed, whic , trough the other tap on the machine, will be used to heat milk and other liquids.
The water for the coffee, pushed by pump to the pressure of 9 BAR (atmosfpheres), passes in a heat spacer inside the boiler, where it is heated and maintained at the correct temperature of about 90°.

PREPARATION
After filling the filter of the hopper, the coffee must be pressed with a force of 10-20 kilos. Generally speaking the good operator will press the coffee in order to compensate any small defects in the grinding. Before hooking it up to the machine group, the rim of the filter holder must be cleaned, because coffee residues may limit the closure (with consequent loss of pression) and form deposits on the gasket, which could deteriorate in a faster way.
The emission of the espresso must be regularly and at “rat-tail cord”; the cup must be hot but it must not burn the client's lips.

MAINTENANCE
Maintenance is fundamental to obtain a perfect espresso: the coffee bean container must be washed regularly to  remove any grease. The inside of the coffee grinder must be brushed with care to remove all the residues, while the hopper must be cleaned with a brush. Every evening the filters must be removed from the filter holder and be washed apart from the filter holder of the machine; the hook-up zone must be carefully cleaned with a little iron brush, during the night it is preferable to leave the machine turned on, mainly to avoid excessive limestone formations; in this regard it is very important to check the water softener.
Calcareous deposits limit the passage of water lowering the temperature and compromising the success of the extraction.
Extraction means a fast process  depending on the degree of the grinding, water temperature, pressure and contact time  between water and powder. 

Moka Rica, esempio di caffè sottoestrattoUNDER EXTRACTED COFFEE
Ocher/yellow uniform cream-colored
Inconsistent cream thickness
Poor substance
Not persistent taste and aroma

Possible causes:
Water temperature < 90°C
Water pressure < 9 BAR
Too coarse grinding
Poor pressing
Low dose of coffee < 7 g
Exit time < 20 seconds

 

Moka Rica, esempio di caffè idealmetne estrattoCOFFEE IDEALLY EXTRACTED
Light brown to reddish cream-colored
Cream thickness 3-4 mm at uniform and fine “grain”
Full substance
Persistent taste and aroma

 

 

 

 

 

 

Moka Rica, esempio di caffè sovraestrattoOVER EXTRACTED COFFEE

Dark brown cream-colored with a light spot in the centre (the so called black hole)
Poor cream thickness
Poor substance
Strong and bitter taste and aroma
Possible causes:
Water temperature > 90°C
Water pressure > 9 BAR
Too fine grinding
Exaggerated pressure
Low dose of coffee > 7 g
Exit time > 32 seconds

 

THE ESPRESSO PARAMETERS
For espresso we mean a little cup of concentrated coffee, extracted from coffee beans grinded at once, which must correspond to the following average parameters:

  • Necessary quantity of coffee 7g
  • Water temperature 90° C
  • Water pressure 9 BAR
  • Compression in the filter about 15 kg
  • Extraction time 25 seconds
  • Quantity in cup 25 ml
  • Temperature of the empty cup 60° C

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