In general, what defines the extraction method for an espresso shot?

The extraction method for an espresso shot is primarily defined by the duration and pressure applied during the extraction process. Espresso is brewed by forcing hot water through finely-ground coffee at high pressure, typically around 9 bars. This high-pressure extraction allows for a quick and efficient extraction of flavors, oils, and aromas from the coffee. The precise duration of the extraction, usually around 25 to 30 seconds, directly influences the taste and quality of the espresso shot. By controlling both the pressure and duration, baristas can manipulate the extraction to achieve desired flavor profiles, body, and crema.

While the temperature of the water, type of coffee bean, and grind size all play significant roles in the brewing process, they do not fundamentally define the method of extraction as pressure and duration do. Temperature affects the solubility of flavors, and grind size influences the surface area for extraction, but it is the combination of pressure and time that characterizes the espresso extraction process specifically.