How Does Machine Espresso Work?

The machine espresso makes use of precise pressure and filtering system that is awe-inspiring to create the coffee you love. How does it work exactly?

uk espresso machine is made by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee but the major difference is in the pressure.

The Group Head

The group head is the portafilter you put in when making espresso. It disperses water in the portafilter, and then controls the pressure of the extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion features, and others are designed to control the lever. Some include a combination like the E61. This is a very popular choice for espresso Home machine baristas because it offers multiple advantages in one package.

As you can see in the photo above, the group head is equipped with several notches. You place your portafilter in these notches, then twist the head to secure it. A gasket made of rubber is positioned in the notches to create a seal as you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is essential for an even extraction.

The group head is not just able to allow you to insert your portafilter easily, but it also maintains the same temperature. It does this by cycling hot water through the brew container and around the portafilter, making sure that it's always at the correct temperature for extraction. This is important because just a few degrees could be the difference between a good and great espresso.

The Pump

Contrary to manual piston machines which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. This pressure is generated 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 degrade due to overuse and insufficient cleaning. Pumps are also more complicated mechanically, which can raise prices of even simple models.

Certain espresso machines do away with the pump completely and instead make use of steam pressure to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water to boiling which could lead to over-extraction. These machines also have to continuously rebuild their pressure between cups. This takes energy and time.

Many espresso machines make use of either a rotary or vibration pump, with a vibrating model using a rotating disc to create pressure and an rotary model that pushes hot water through the grounds under high speed. Both models are capable of producing excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler will heat the water to the right temperature for extraction. The resulting steam reaches the portafilter containing the ground espresso and is then pumped down into the cup. In this process, the steam causes pressure to push through the coffee grounds. This creates a crema on top of the espresso. This is one of the main characteristics of a great retro espresso machine.

There are three kinds of espresso makers, and they differ in the type of pump they use and the degree of heat that the coffee is. There are various ways that the brew may be controlled and the dimensions of the cup the machine can make.

The earliest espresso machines were steam-based. They used one boiler to make both brew and steam, however, the pressure they could generate was low - only two bars of atmospheric pressure at the most. This led to the coffee tasting burnt and bitter. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic that has an electric pump. These are the images people have when they think of an espresso machine. Semi-automatic machines require you to grind and tamp your beans yourself however the pump controls the flow of water and pressure. This is a great combination of human control and mechanised accuracy.

The Filter

Typically, espresso machines employ filters that separate the coffee grounds as they pass through the hot water. The filter is also a vital part of the machine's temperature control, since it stops overheating.

It also helps with flavor as a filter can allow for a longer bloom phase. This helps the beans release their flavor and gives an opportunity for a better extraction.

It is important to keep in mind that even the best filter can result in a bad cup of coffee. The quality of the beans as well as the extraction, remain vital.

It's here that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you place the portafilter - the thingy that you put the coffee grounds in, when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam, which is then pushed through the grounds under high pressure. They are less expensive and easier to maintain than pumps-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 ideal shot requires 9-10 bars.

In recent years, compressed air-pump-driven Espresso home Machine machines have become more popular. They utilize an air compressor to force hot water into the grounds and are more portable than steam-driven electric machines.