Espresso (Photo: 520 Coffee Network)

Espresso (Espresso) or espresso is a type of coffee with a strong taste by brewing coffee with extremely hot but non-boiling hot water under high pressure and grinding it into a very fine coffee powder. It was invented and developed in Italy and began in the early 20th century, but until the mid-1940s, it was a drink made separately through vapor pressure. After the invention and successful commercialization of the Spring Lever (spring piston lever) coffee machine, espresso was transformed into a drink known today. The production process is to extract about 30cc coffee liquid from hot water with a temperature of about 90 ℃ at 9 to 10 atmospheric pressure or bar pressure in 20 to 30 seconds.

From the above definition, espresso has a thicker texture than ice-drop coffee and contains more dissolved matter per unit volume than water-drop coffee; supply is usually measured in "shot". Espresso is chemically complex and changeable, many of which decompose due to oxidation or a drop in temperature. A feature of properly brewed espresso is the presence of coffee fat (crema), a reddish-brown foam that floats on the surface of espresso. It consists of vegetable oils, proteins and sugars. Coffee fat has the combination of emulsion and foam colloid.

Through the short-time and high-pressure brewing process, the unique flavor of a cup of coffee is stronger than other brewing equipment after being concentrated. However, there is less caffeine because of the short quenching time. Espresso is often used as the basis for coffee drinks mixed with other ingredients (such as milk or cocoa), such as lattes, cappuccinos, caramel macchiato and mocha, without over-diluting the coffee.