Coffee and Espresso Machines Espresso machines make use of pressure to push water through finely ground and tamped coffee beans. They create a rich and delicious brew. Experts from the Good Housekeeping Institute recommend models that brew with the minimum pressure of 9 bars in order to achieve optimal extraction. https://coffeee85867.theisblog.com/29982147/espresso-machine-explained-in-fewer-than-140-characters