Pressure is a measure of how well matter opposes a reduction in available space. In the context of coffee preparation, the right pressure is crucial. For example, espresso is usually made with a portafilter machine under high pressure. This pressure, also known as brewing or steam pressure, forces hot water through the coffee powder, extracting more flavor. Similar principles apply to coffee pod machines and fully automatic machines.
The right pressure is critical when brewing espresso. Too little pressure results in pale, weak and watery crema, while too much pressure makes the espresso taste too dark and bitter. In extreme cases, very high pressure can even prevent extraction. For optimal results, a pressure of 9 bar is recommended. Many coffee machines are already preset to this pressure, although some home machines may be set to 12 bar to more easily produce the typical crema in espresso.
Coffee machines that work with pressure, such as portafilter machines, use an electric pump to create the necessary pressure. These machines heat water in a boiler and then transport it to the brewing group, where the pump creates the pressure to force the water through the coffee powder. The electric pump plays a crucial role in creating the desired pressure for coffee extraction.
