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How Does Machine Espresso Work?

The machine espresso uses precise pressure, as well as a filter technology that is mind-blowing to create the coffee you love. But how exactly does it work?

To make espresso machines for home hot water is pushed under 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 name implies the group head is where you place your portafilter when making espresso. It disperses the water into the portafilter and regulates the pressure of the extraction. There are a variety of types of group heads each with its unique advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion options, and others are designed to control the lever. There are some that have a combination of features, such as the E61, which is the most popular choice among baristas due to its ability to provide multiple benefits in a single package.

As you can see in the above photo The group head features several notches to put your portafilter, then twist it manually to secure it. There is also a gasket made from rubber which is located inside the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches allow for precise placement of your portafilter. This is crucial to ensure a consistent extraction.

In addition to allowing you easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew basket and around the portafilter, making sure that it is always at the correct temperature for extraction. This is important because just a few degrees could mean the difference between excellent and great espresso.

The Pump

The motorized pumps in espresso machines that rotate provide the nine atmospheric bars of pressure required to extract espresso. This differs from manual piston machines that rely on a lever. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior being pushed through the ground coffee in the group head.

Pumps are generally less expensive than piston-driven machines and tend to last longer, but both types of machines may degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even simple models.

Some espresso machines do away with the pump entirely and use steam pressure to brew espresso. This can lead to over-extraction as the boiler that produces steam also heats the water until it comes to a boil. They also have to constantly rebuild their pressure in between cups. This requires energy and time.

A majority of espresso machines use the rotary or vibration pump, which is a vibration model using a rotating disc that generates the pressure, and an rotary model that pushes hot water through the grounds at high speed. Both machines can produce excellent espresso, however rotary machines are more quiet, durable and less likely to break.

The Boiler

The boiler is the one that makes the water warm to the perfect temperature for extraction. The resulting steam reaches the portafilter containing the ground espresso coffee and gets funnelled down into the cup. During this process the steam generates enough pressure to push the grounds of the coffee and espresso machine through. This results in a crema on top of the espresso. This is one of the main characteristics of a good barista espresso machine.

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

The first espresso machines were steam-type. The earliest espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso machine is a semiautomatic model with an electric pump. These are the things people think of when they think of an espresso machine. With a semi-automatic espresso machine, you must grind the beans and tamp them by hand. However, the pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanized accuracy.

The Filter

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

It also helps with flavor, since a filter allows for a more prolonged bloom time. This helps the beans release their nuances and gives an opportunity for a better extraction.

It is important to keep in mind that even the best bean to cup espresso machine filter can produce a bad cup of coffee. The quality of the beans and the extraction process, remain crucial.

It's here that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, also called the brew head, is where the portafilter (the thing you put the coffee ground into) sits when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to make steam. The steam then moves hot water through the grounds of the coffee under pressure. These kinds of machines are generally cheaper and easier to maintain than pumps-driven models. They are however limited in their ability 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, compressed-air-pump-driven espresso machines have become more popular. They make use of an air compressor to force hot water into the ground and are much more mobile than electric steam-driven espresso and filter coffee machine machines.