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How Does Machine Espresso Work?

The machine espresso makes use of precision pressure, and filter technology that is awe-inspiring to create the coffee you love. But 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 but the key difference is in the pressure.

The Head of the Group

The group head is the portafilter you put in when making espresso. It disperses water in the portafilter, and then regulates the pressure during the extraction. There are numerous kinds of group heads each with distinct advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some have a combination of features, such as the E61 that is the standard choice for many baristas for its ability to provide multiple benefits in a single package.

As you can see from the picture above, the group head is equipped with several notches. You place your portafilter in these notches, then twist the head to secure it. There is also a rubber gasket that is a part of the notches and helps to create the seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is vital for an accurate extraction.

The group head not only allows the portafilter to be inserted easily however it also keeps an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is always at the right level for extraction. This is vital, because just a few degrees could make the difference between good and great espresso.

The Pump

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

Pumps are generally less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and poor cleaning. Pumps are also more complex mechanically, which can raise the cost of even the simple models.

Certain espresso machines utilize steam pressure instead of a pump to brew espresso. This could lead to over-extraction since the boiler that produces steam also causes the water to boil. These machines also have to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines make use of the rotary or vibration pump, with a vibration model using a vibrating disc to generate the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both machines can make great espresso, but rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler is the part which heats the water to the ideal temperature for extraction. The resultant steam then reaches the portafilter which holds the ground espresso coffee, and is then pumped into the cup. The steam creates pressure that pushes through the grounds of the coffee. This creates a layer crema on top. This is one of the main characteristics of a great espresso.

There are three kinds of espresso makers, which differ in the type of pump they employ and how hot the espresso is. There are various 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 types. They had one boiler to create both steam and brew but the pressure they could produce was not very high - two bars of atmospheric pressure at the most. The coffee tasted bitter and burned. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most well-known espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic espresso machine (Continued), you have to grind the beans and then tamp them by hand. However, the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and the mechanized consistency.

The Filter

best espresso machine machines usually have filters that separate the grounds of the coffee from hot water. The filter is also a crucial component of the temperature control system, because it stops the machine from overheating.

It also aids in flavor, since a filter allows for a more prolonged bloom time. This helps the beans to let their nuances out and provides an opportunity for a better extraction.

However it is crucial to keep in mind that even a high-quality filter can make a terrible cup of coffee for espresso machine, as the quality of the beans and extraction is essential.

This is where the magic happens, and it's what makes espresso taste good. The grouphead, also referred to as the brew head, is where the portafilter (the container you place the coffee grounds into) sits when you're making espresso.

In the steam-driven discount espresso machines machine hot water is heated in an airtight tank to create steam, which is then pushed through the grounds at high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect brewing conditions because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, espresso machines driven by compressed air-pump are becoming increasingly popular. They utilize an air compressor to push hot water across the ground and are much more mobile than electric steam-driven espresso machines.