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 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://www-coffeee-uk03230.bcbloggers.com/29294467/from-the-web-the-20-most-amazing-infographics-about-espresso-machine