How Does Machine Espresso Work?

The machine espresso is made using precise pressure, as well as a filtering system that is awe-inspiring to create the coffee you enjoy. How does it work exactly?

Espresso is made by pushing hot water at high pressure through finely ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.

The Group Head

As the name implies the group head is the place you place your portafilter when making espresso. It disperses water in the portafilter and regulates the pressure during the extraction. There are several different types of group head each with its particular advantages and drawbacks. Some focus on temperature stability, some on pre-infusion features, and others are designed to control the lever. Some include a combination such as the E61. This is a preferred choice for baristas as it provides a variety of benefits in a single package.

As you can see in the above photo the group head comes with several notches to place your portafilter before twisting it by hand to lock it in. There is also a rubber gasket in the notches and helps to create an airtight seal when you insert your portafilter into the machine. The notches on the head permit a precise placement of the portafilter, which is vital to ensure an efficient extraction.

The group head not only lets the portafilter to be inserted easily, but it also maintains the same temperature. It does this by cycling hot water through the brew pan and around the portafilter, ensuring that it is always at the right temperature to extract. It is crucial to keep in mind that even a small deviation can make the difference between a great and a great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure necessary to extract espresso. This pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are typically less expensive and last longer than piston-driven machines. However, both types of machines can degrade due to overuse and inadequate cleaning. They also add mechanical complexity that can lead to the cost of even the most basic models.

Some espresso machines can eliminate the pump completely and utilize steam pressure to make espresso. This can lead to over-extraction as the boiler that produces steam also heats the water to boil. The machines must also constantly rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize an rotary or vibrating pump, with a vibration model that uses a vibrating disc to create the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both models can make a great espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats the water to the optimal temperature for extraction. The resulting steam is then transferred to the portafilter which holds the ground espresso coffee, and espresso machines is then funneled down into the cup. During this process, steam creates pressure that pushes through the coffee grounds. This creates a crema on the top of the espresso. This is the hallmark of a great espresso.

There are three kinds of espresso machines, each with different pumps and brew temperature. There are a variety of ways to control the brew as well as the size of cup that can be made by the machine.

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

The most well-known espresso machine is a semiautomatic model with an electric espresso maker pump. When people think of espresso machines, they picture these machines. With a semi-automatic machine, you must grind the beans and tamp them by hand, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and mechanized consistency.

The Filter

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

A filter also helps with flavor since it allows for a longer flowering phase. This allows beans to release their flavors and provides an opportunity for a better extraction.

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

This is where the magic happens, and it's what makes an espresso really taste good. The grouphead (also called the brewhead) is where you put the portafilter, the device that you use to put the coffee grounds in, when making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to make steam. The steam then pushes hot water through grounds of coffee under high pressure. These kinds of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited for creating the ideal conditions for brewing 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 use an air-compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.