Coffee and Espresso Machines Espresso machines make use of pressure to force water through finely ground and tamped coffee beans. They create a rich and flavorful 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://coffeee55619.blogkoo.com/12-facts-about-espresso-machine-to-make-you-seek-out-other-people-49405380