Coffee and Espresso Machines Espresso machines make use of pressure to force water through finely ground and tamped coffee beans. They produce a rich and delicious cup of coffee. Experts from the Good Housekeeping Institute recommend models that brew at a minimum pressure of 9 bars to achieve optimal extraction. https://wwwcoffeeeuk62097.tribunablog.com/20-fun-facts-about-espresso-machine-44148687