How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the delicious coffee we enjoy. How does it work exactly?

To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.

The Group Head

The group head is the portafilter that is inserted when you are making espresso. It disperses water into the portafilter and regulates the pressure of extraction. There are a variety of group heads, each with its own advantages and drawbacks. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. Some have a combination, like the E61. This is a popular choice among baristas since it provides multiple advantages in one package.

As you can see in the photo above, the group head is fitted with a variety of notches. It is possible to place your portafilter in these notches and then turn the head around to secure it. There is also a rubber gasket which is located inside the notches, which helps create a seal when you insert your portafilter into the machine. The notches on the head allow for a precise placement of the portafilter, which is vital to ensure an even extraction.

Aside from allowing you to easily connect your portafilter, the group head is responsible to ensure that the temperature remains even. This is accomplished by cycling hot water around the portafilter, and through the brew basin, ensuring the temperature is always right to extract the coffee. This is crucial, since even a few degrees can make the difference between good and excellent espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure required for espresso extraction. The pressure is built by pumping water through a heat exchanger and then through the ground coffee and espresso machine.

Pumps are typically less expensive than piston-driven machines, and tend to last longer, although both types of machines could get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, which can increase the cost of even the simplest models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso. The drawback of this is that the same boiler that produces steam also raises the temperature of water until it reaches boiling and can result in excessive extraction. The machines also need to continuously rebuild their pressure between cups. This requires energy and time.

A majority of espresso machines use an rotary or vibrating pump, which has a vibration model that uses a vibrating disc to generate the pressure, and rotating models that push hot water through the grounds under high speed. Both machines espresso can produce excellent espresso, however rotary machines are more stable, quieter and less likely to break down.

The Boiler

The boiler is the part that heats the water to the ideal temperature to extract. The steam that is produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process, steam creates pressure that pushes through the coffee grounds. This results in a whipped-up top of the espresso. This is a sign of a good espresso.

There are three types of espresso machines, each having a different type of pump and brew temperature. There are a variety of ways to control the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam types. The first espresso machines were steam types. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic that has an electric pump. When people think of best small espresso machine machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans yourself The pump, however, regulates the water flow and pressure. This is a great compromise between the human touch and the mechanized accuracy.

The Filter

Typically, espresso machines use filters to separate the grounds of coffee as they move through the hot water. The filter is also an important part of the temperature control system, since it helps prevent the machine from overheating.

It also improves flavor, since a filter lets you enjoy a longer bloom time. This allows beans to release their nuances and gives the chance for better extraction.

It is important to keep in mind that even the best coffee espresso machine filter could result in a poor cup of coffee. The quality of the beans, and the extraction, remain vital.

It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy used to place the coffee grounds into, when making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through the coffee grounds under high pressure. These types of machines tend to be less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water through grounds, and are far more portable than electric steam-driven machines.