Espresso is not a variety of coffee bean, style of roasting, or a brand; Espresso is a preparation method and one of the most popular methods for enjoying coffee. Espresso is a beautiful concentrate full of aroma and body topped with an emusion(crema) bursting with flavour and aroma. Well made espresso is as enjoyable as a fine red wine or high quality bitter chocolate.
Espresso is a concentrated coffee beverage
Espresso is a concentrated beverage created by forcing a small volume of hot water under pressure through finely ground roasted coffee beans. The high pressure combined with the hot water "extracts" both oil and dissolved solids from the ground coffee beans producing a thick almost syrupy beverage. The oil and water combination forms an emulsion known as crema which sits as a thick layer on top of a well made cup of espresso. This crema is widely regarded as a key indicator of a good quality espresso.
History
Espresso coffee was invented and perfected in Italy in the first decade of the 20th century. Espresso literally tranlates as "express" or fast. Prior to the advent of the espresso brewing process, coffee brewing was quite slow using methods such as drip filter, or french press (plunger). The true start of the espresso revolution came in 1905 when Desidero Pavoni bought Luigi Bezzeras patent for an espresso machine, made some improvements, and began production of the first truely commercial espresso machine, model "Ideale"
Espresso Brewing Process
Espresso is made by forcing hot (almost boiling) water through finely ground, compacted coffee. Coffee is ground using a coffee grinder and packed into a portafilter or filter holder and compressed or tamped to form a tightly packed disc or puck of coffee.
The filter holder is connected to an espresso machine which provides heated water at a sufficient rate of flow. The resistence provided by the compressed coffee forces the heated water to flow through the coffee at a high pressure, releasing both oil and solids from the coffee beans which mix and dissolve with the water to form espresso.
By the numbers
Strictly speaking there is no authorative definition of what an espresso is, but generally speaking the vast majority of espresso equipment manufacturers are designed to produce espresso based on the following parameters:
Coffee Dose
8 +/- 1 grams of freshly ground coffee per single shot of espresso
7 - 9 grams of freshly ground coffee evenly distributed in a single portafilter
14 - 18 grams of freshly ground coffee evenly distributed in a double portafilter
Water temperature
90 +/- 2 degrees centigrade
88 - 92 degrees centigrade at the point of extraction
Extraction pressure
9 bar (130 psi)
Extraction time
5 seconds pre-infusion + 25 seconds extraction
30 seconds maximum
Volume in the cup
25 +/- 5 ml per per single shot of espresso
20 ml for a ristretto (restricted) espresso
30ml for a completely extracted espresso
2x 20ml for two ristrettos
2x 30ml for two espressos
Equipment
Espresso is made by forcing hot (almost boiling) water through finely ground coffee, compacted coffee.
Espresso is not a variety of coffee bean, style of roasting, or a brand; Espresso is a preparation method and one of the most popular methods for enjoying coffee. Espresso is a beautiful concentrate full of aroma and body topped with an emusion(crema) bursting with flavour and aroma. Well made espresso is as enjoyable as a fine red wine or high quality bitter chocolate.
Why does espresso taste so good?
Like chocolate or wine, espresso coffee is an extraordinary substance; full of complexity with a distinctive aroma, taste, texture, and mouth-feel. The espresso beverage contains acids, proteins, sugars, fats either suspended or dissolved in water; it is the balance of all these elements that produces the satisfaction derived from a great espresso.
How is espresso made?
Espresso is 25-30ml of concentrated coffee produced from 7-9grams of ground coffee beans, extracted with hot water under a pressure of 9 bar for 25-30 seconds.
Coffee Dose
between 7-9 grams of freshly ground coffee compressed into the filter basket
Water temperature
the water passing through the compressed ground coffee must be between 88 and 92 degrees celcius.
Extraction Pressure
extracton of espresso relies on pressure to force the critical fats, proteins, sugars, and acids from the coffee bean and dissolve these into the water. Hot water is forced through the compressed ground coffee under a pressure of 9-10 bar using either a mechanical lever or a special pump.
Volume
the volume of liquid, emulsion, and suspension produced for a single espresso shot if between 25-30ml depending on timing, dosing, and the type of bean being used.
Extraction time
the extraction time take to produce one espresso is 25-30 seconds from when coffee first appears until the