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How Does Machine Espresso Work?

Machine espresso coffee machine for home uses precision pressure and mind-blowing filter technology to create the delicious coffee we enjoy. But how exactly does it work?

Espresso is made by forcing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee. However, the pressure is the main difference.

The Head of the Group

As the name implies the group head is where you place your portafilter while brewing espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the resulting extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are designed for the stability of temperature while some are designed to handle pre-infusion. Some are designed to control the lever. Some have a combination of features, such as the E61, which is the classic choice among many baristas because of its ability to offer multiple perks in a single package.

As you can see in the photo above, the group head has many notches in which you can put your portafilter, then twist it manually to lock it in. There is also a gasket made from rubber that resides inside the notches and helps create the seal when you insert your portafilter into the machine. The notches on the head allow for a precise position of the portafilter which is crucial to ensure a consistent extraction.

The group head not only allows you to insert your portafilter easily but also maintains the temperature at a constant level. It does this by cycling hot water through the brew pan and around the portafilter, making sure that it is always at the correct temperature for extraction. It is important to remember that even a slight variation can mean the difference between a good and a great espresso.

The Pump

Motorized pumps in rotary espresso machines Espresso machines provide the nine atmospheric bars of pressure required to extract espresso. This is different from manually operated piston machines that employ levers. The pressure is created by removing tap water from a reservoir and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.

Pumps are typically more affordable and last longer than piston-driven machines. However, both kinds of machines can degrade due to excessive use and poor cleaning. They also add mechanical complexity, which can result in a high price tag on even the simplest models.

Some espresso machines do away with the pump completely and instead utilize steam pressure to make espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of water until it reaches boiling which can cause over-extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize either a rotary or vibration pump, with a vibration model using a vibrating disc that generates the pressure, and a rotary model pushing 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 down.

The Boiler

The boiler is the part which heats the water to the ideal temperature to extract. The resultant steam then reaches the portafilter, which contains the ground espresso and gets funnelled down into the cup. The steam causes enough pressure to push the grounds of coffee through. This creates a crema on top of the espresso. This is one of the main characteristics of a great espresso.

There are three different types of espresso machines, each having different types of pumps and brew temperature. There are various ways to control the strength of the brew and the size of cup that can be produced by the machine.

The first espresso machines were steam-type. They had a single boiler to make steam and brew, however the pressure they were able to produce was very low - just two bars of atmospheric pressure at the most. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso machine is a semiautomatic one with an electric pump. These are the things people think of when they think of an espresso machine. With a semi-automatic espresso machine with milk frother machine, you must grind the beans and tamp them yourself but the pump is able to regulate the flow of water and pressure. This is a great compromise between human control and mechanised consistency.

The Filter

Typically, espresso machines have filters that 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 prevents the machine from overheating.

It also helps with flavor, as it can allow for a longer bloom time. This allows the beans to release their flavor and gives an opportunity to improve extraction.

However, it is important to keep in mind that even a great filter can produce a bad cup of coffee, because the quality of the beans and extraction is still important.

This is where the magic happens. It's what makes an espresso really taste good. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy that you put the grounds of your coffee into while making espresso.

In the steam-driven buy espresso machines machine hot water is heated in an airtight container to produce steam, which then pushes the hot water through the grounds with high pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

In recent years, espresso machines powered by a compressed air pump have become increasingly popular. They make use of an air compressor to push hot water through the ground and are more mobile than electric steam-driven espresso machines.