It is thicker than coffee brewed by other methods, has a higher concentration of dissolved solids, and has cream on top. Espresso is also the base for other drinks such as a caffè latte, cappuccino, caffè macchiato, caffè mocha, flat white, caffè Americano and other types.
Base for other drinks
Espresso is also the base for other drinks such as a caffè latte, cappuccino, caffè macchiato, caffè mocha, flat white, or caffè Americano. Espresso has more caffeine per unit volume than most coffee beverages, but because the usual serving size is much smaller, the total caffeine content is less than a mug of standard brewed coffee, contrary to a common belief.
Espresso brewing
There is no universal standard defining the process of extracting espresso, but there are several published definitions which attempt to place constraints on the amount and type of ground coffee used, the temperature and pressure of the water, and the rate of extraction. Generally, one uses an espresso machine to make espresso.
The act of producing a shot of espresso is often termed “pulling” a shot, originating from lever espresso machines, which require pulling down a handle attached to a spring-loaded piston, forcing hot water through the coffee at high pressure. Today, however, it is more common for the pressure to be generated by an electric pump.
Coffee is usually brewed immediately before drinking. In most areas, coffee may be purchased unprocessed, or already roasted, or already roasted and ground.
Roasting coffee transforms the chemical and physical properties of green coffee beans. When roasted, the green coffee bean expands to nearly double its original size, changing in color and density.