How do espresso machines work

How does an espresso machine work?

The principle of operation

The special thing about an espresso machine is that the water is pressed through the espresso powder at a pressure of 9 bar. Due to this high pressure, the coffee powder comes into contact with the water for about 25 seconds. Therefore, several conditions must be met for the espresso to be successful:

  • The espresso beans must be finely ground (grinding degree 2 to 3) so that the water can absorb sufficient aroma in the short time. The finer the beans are ground, the larger the contact surface and the more aroma the water can absorb.
  • The espresso powder needs to be pressed down firmly so that it cannot fly around as soon as the water hits it. Coffee grinders are often equipped with a tamper for pressing down the espresso powder. Since you are only pressing the portafilter against it from below, you cannot exert sufficient force here. We therefore recommend that you purchase a rubber mat and a tamper made of stainless steel. So you can support the portafilter on the rubber mat and press the espresso powder briefly but firmly with the tamper.
  • The espresso powder in the portafilter must be evenly distributed so that there are no channels. To do this, fill the portafilter to the brim with espresso powder and wipe off the excess powder with a finger without pressing the powder!

There are also espresso machines where the pressure can be adjusted, even beyond 9 bar. This is more for coffee professionals who like to play a little with taste. In general, 9 bar is the optimal pressure.

Building an espresso machine

The pressure is usually generated by an electric pump. This transports hot water at 90 to 95 ° C to the brewing group, where the portafilter is attached.
A good espresso machine also has a steam wand that is used to froth the milk and a spout for hot water, e.g. to prepare tea or espresso coffee. These two outputs are either connected to the same water boiler (single circuit) or have a separate water circuit (dual circuit) or even their own boiler (dual boiler), because the water temperature required here is 120 to 130 ° C. You can find out more about single-circuit, dual-circuit and dual boilers here.

Experiment a little with your espresso machine: press the espresso powder lightly once and overdo it once. You will undoubtedly notice the difference in espresso taste!

Author: Sara Müller - Note: All information is without guarantee. Home »Living» Kitchen »Coffee machine» Espresso machine