How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. How exactly does it work?

In order to make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.

The Group Head

As the name implies the group head is the place you place your portafilter when making espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure of the extraction. There are many different kinds of group head, each with their particular advantages and disadvantages. Some focus on temperature stability, some on pre-infusion capabilities, and still others are designed to control the lever. Some come with a combination of both, like the E61. This is a very popular choice for baristas because it offers multiple advantages in a single package.

As you can see in the above image the group head comes with several notches to place your portafilter before twisting it by hand to lock it in. A gasket made of rubber is positioned in the notches to create a seal when you insert your portafilter. The notches on the head allow for an exact positioning of the portafilter which is necessary for an even extraction.

In addition to allowing you to easily connect your portafilter, the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew pan and around the portafilter, ensuring that it is always at the correct temperature for extraction. This is important, as even a few degrees can be the difference between a good and excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure necessary to extract espresso. This pressure is built up by pumping water through a heat exchanger and then through the ground coffee.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and insufficient cleaning. Pumps are also more complex mechanically, which can raise prices of even most basic models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso. The drawback of this is that the boiler that produces steam also increases the temperature of the water to boiling which can cause over-extraction. In addition these machines typically have to rebuild their pressure between cups, which requires time and energy.

A large majority of espresso machines employ an rotary or a vibration pump. A vibration model utilizes the vibrating disk to create pressure, whereas a rotary model pushes hot water through the ground at a rapid speed. Both machines produce great espresso, however rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the one that will heat the water to the right temperature for extraction. The steam created will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. The steam is then channeled into the cup. In this process, the steam creates pressure and pushes through the coffee grounds. This produces a layer of crema that is then poured over. This is one of the main characteristics of a great espresso.

There are three kinds of pro espresso machine machines, each with distinct pumps and the temperature of the brew. There are a variety of ways in which the brew could be controlled, as well as the size of the cup that the maker can create.

The earliest espresso machines were steam type. They employed only one boiler to make both brew and steam, however, the pressure they could produce was not very high - two bars of atmospheric pressure maximum. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semiautomatic machine with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans by yourself however the pump controls the flow of water and pressure. This is a great compromise between the human touch and mechanized accuracy.

The Filter

Typically, espresso machines utilize a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also an essential element of the temperature control system because it stops the machine from overheating.

It also aids in flavor, as a filter lets you enjoy a longer bloom phase. This allows the beans to let their nuances out, and also allows for better extraction.

It is important to keep in mind that even the Best espresso Machine Under 200 filter can make a bad cup of coffee. The quality of the beans, and the extraction process, are still crucial.

It's here that the magic occurs. This is what makes espresso taste so good. The grouphead, also called the brew head, is the place where the portafilter (the thing you put the ground coffee into) sits when you're making espresso.

In a steam-driven barista espresso coffee machine machine hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds under high pressure. These types of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited for creating the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, espresso machines driven by compressed air-pump have become increasingly popular. They utilize an air compressor to push hot water through the grounds and are significantly more portable than steam-driven electric machines.