How Does Machine Espresso Work?

Machine espresso employs precise pressure and amazing filter technology to make the perfect cup of coffee. How exactly does it work?

best espresso machine under 500 is made by pushing hot water under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the primary difference.

The Head of the Group

The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are many different kinds of group heads each with its own 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 like the E61. This is a preferred choice for baristas since it provides multiple benefits in one package.

As you can see in the photo above, the group head has several notches to place your portafilter before twisting it manually to lock it in. A rubber gasket is located in the notches to make a seal when you insert your portafilter. The notches on the head permit a precise placement of the portafilter, which is essential to ensure an even extraction.

The group head does not just allow you to insert your portafilter easily, but it also maintains an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is always at the right level for extraction. This is vital, because even a few degrees can be the difference between a good and excellent espresso.

The Pump

The motorized pumps that are used in espresso machines rotary provide nine atmospheric bar pressure needed to extract espresso. This is different from manual piston machines that rely on levers. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven machines and tend to last longer. However, both types of machines may degrade with overuse and insufficient cleaning. They also make mechanically complex that can lead to the cost of even the most basic models.

Some espresso machines use steam pressure instead of a pump in order to brew espresso. The downside is that the boiler that produces steam also raises the temperature of the water until it reaches boiling which could lead to over-extraction. In addition these machines are often required to restore their pressure between cups, which requires time and energy.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model uses a rotating disk to generate pressure, whereas a rotary model pushes hot water through the ground at a fast speed. Both types of machines can make excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is what is used to heat the water to a temperature that is ideal for extraction. The steam that is produced reaches the portafilter that contains the ground espresso and is then pumped down into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This creates a layer crema that is then poured over. This is a sign of a good espresso.

There are three kinds of espresso makers. They differ in the type of pump they use and how hot the espresso is. There are different ways that the brew may be controlled, as well as the size of the cup that the maker can create.

The first espresso machines were steam types. They employed one boiler to create both steam and brew, however, the pressure they could produce was not very high Siemens EQ9 s300 - Black: Premium Automatic Melitta Barista TS Smart Coffee Machine 1450W: Premium Quality Black Brewer Machine (try these guys) two bars of atmospheric pressure at most. This led to the coffee tasting bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most well-known espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they picture these machines. If you have a semi-automatic machine you grind the beans and then tamp them by hand, but the pump provides regulated water flow and pressure. This is a perfect compromise between human control and mechanized accuracy.

The Filter

Typically, espresso machines employ filters to separate the grounds of coffee when they pass through the hot water. The filter is also an essential part of the temperature control system, as it keeps the machine from overheating.

A filter also improves flavor, as it permits a longer flowering phase. This lets the beans let their nuances out, and improves extraction.

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

It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is the place where the portafilter (the thing you put the ground coffee in) is placed when you're making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds under high pressure. They are less expensive and easier for the owner to maintain than pumps-driven models. They are however limited to create the perfect 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 machines have become more popular. They use an air compressor to force hot water into the ground and are much more mobile than electric steam-driven espresso machines.