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 tasty brew. Experts from the Good Housekeeping Institute recommend models that brew at the minimum pressure of 9 bars in order to achieve optimal extraction. https://www.coffeee.uk/products/quest-36569-espresso-machine-with-milk-frother-15-bars-pressure