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The espresso

 

The espresso is the original Italian system to make coffee. Its popularity grew by the mid-twentieth century, after several efforts pretending the extraction of the volatiles substances from the coffee bean in order to obtain "the best coffee ". They developed a system and a machine that provides hot water under pressure (about 8 bars) and the jet passes through the roasted and ground coffee.

This way of making coffee has completely subject the world and has found its place among us, with similar characteristics, but with the need to establish processing conditions to distinguish the espresso from other preparations.

The espresso is obtained from an extraction of the components of roasted and ground coffee by means of hot water under pressure for a given time, and served in special cups, according to the following standardized parameters:

 

  • Quantity of ground coffee  .............................. 7g
  • Quantity of water      ....................................... 25ml
  • Water temperature ........................................ 90 ° C
  • Water pressure............................................... 8,5 bar
  • Extraction time .............................................. 25''
  • Initial cup temperature .................................. 40 ° C

 

Such a strictly requirements makes the espresso perfect and different from any form of preparing coffee. A single variation of any of these parameters results as a coffee drink that can no longer be called espresso.

An espresso has to be prepared and enjoyed promptly, taking care of the some factors that affect the consumer´s satisfaction.

Environmental Factors:

Humidity. Roasted coffee is a very hygroscopic product and can easily be compacted in high humidity environments, so any variation of the relative humidity alters the extraction quality because coffee retains or releases moisture while grinding. Optimum relative humidity should not exceed 55%.

Temperature . The ideal temperature to keep fresh coffee is about 13ºC. High temperatures cause exudation of the oils and accelerate the oxidation process.

Sunlight. Better keep coffee in opaque places to prevent oxidation. Both, sunlight and high temperature, are factors that alter the conservation and damage the finest aromas.

 

Equipment factors: 

Grinder burrs. The correct adjust of the grinder burrs is essential. Extraction time is the main indicator of the correct particle-size; it has to be 25 seconds per 25 millilitres of water. There are two cases of low quality extraction:

Over-extracted coffee. For the same volume of water the extraction time is longer because the coffee particles are too slight and/or the dose of coffee is excessive. This involves overheating and the ejection of negative components, resulting a coffee with a strong, bitter taste and a dark and receding crema.

Under-extracted coffee. For the same volume of water the extraction time is shorter because the coffee particles are too coarse and/or the use of an insufficient dose of coffee. The brewing process has not allowed the extraction of noble components of coffee and, as a result, you get a watery, unbalanced coffee with fragile crema.

Water temperature depends on the roasting point of coffee. If dark roast, the best temperature is at 86ºC, if light roast, the correct temperature should be set at 90ºC. The machine has to work at steady temperature for all the extraction operation. 

Pressure must be set between 8 and 9 bar during the extraction process.

Machine cleaning is very important to prevent the espresso from improper flavours.

Ingredient factors:

Water purity. A cup of espresso is 98% water. We need to filter water because it warrants result and will prevent the machine from numerous damages.

 

Coffee beans.  Roasted coffee quality is very delicate and it is preserved for a very short period of time, then, coffee packaging is very important and ground coffee must be used in a short period of time.

 

Roasting degree. If coffee is roast darker, the espresso will be more intense and slightly bitter. This aspect is also related to the variety and origin of coffee: Arabica is finer and more aromatic than Robusta variety.

 

Coffee blend. The blend is the mixture of coffee beans from different regions because this contributes to the richness of organoleptic characteristics of each product.

 

Sensorial characteristics to identify an authentic espresso:

  • Visual presence of the crema, colour and texture
  • Fine, complex aroma
  • Bitter-sweet balanced taste with a touch of acidity
  • Full body
  • Persistent aftertaste and pleasant flavour, free from any aromatic deficiency.

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