How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the perfect cup of coffee. What exactly is it that makes it work?

Espresso is made by pushing hot water at 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 that you put in when making best budget espresso machine. It disperses the water into the portafilter, and then regulates the pressure of extraction. There are several different types of group heads, each with their unique advantages and drawbacks. Some focus on temperature stability, while others on pre-infusion options, and others are designed to control the lever. There are some that contain a variety of features, like the E61 one, which is the classic choice among many baristas due to its capacity to offer multiple perks in one package.

As you can see from the photo above the head of the group is fitted with a variety of notches. You can place your portafilter in these notches, then twist the head to lock it. A gasket of rubber is situated within the notches to create a seal as you insert your portafilter. The notches on the head allow for a precise position of the portafilter which is essential for an even extraction.

Aside from allowing you to easily connect your portafilter, the group head is responsible for maintaining an even temperature. This is achieved 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. It is important to realize that even a tiny difference can make the difference between a great and a excellent espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure needed for espresso extraction. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically less expensive and last longer than piston-driven machines. However, both types of machines may degrade because of excessive use and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even simplest models.

Some espresso machines use steam pressure instead of a pump to make mini espresso maker. This could lead to over-extraction since the boiler that makes steam also heats the water until it comes to a boil. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time.

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

The Boiler

The boiler is the component that heats the water to the ideal temperature for extraction. The steam produced is then directed to the portafilter, which is the container that holds the espresso coffee grounds. It is then funneled into the cup. The steam causes enough pressure to push the coffee grounds through. This results in a layer of crema on top. This is one of the hallmarks of a great espresso.

There are three types of espresso machines, each with distinct pumps and brew temperature. There are various ways to control the brew and the size of the cup that can be made by the machine.

The first espresso machines were steam-type. They used one boiler to make both steam and brew but the pressure they could produce was not very high - two bars of atmospheric pressure maximum. This led to the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machine with frother machines, they picture these machines. If you have a semi-automatic machine you must grind the beans and then tamp them by hand. The pump is able to regulate the flow of water and pressure. This is a fantastic combination of human control and mechanized accuracy.

The Filter

Typically, espresso machines have filters that separate the coffee grounds as they pass through the hot water. The filter is also an essential element of the machine's temperature control, since it helps to prevent overheating.

A filter also helps with flavor as it allows for a longer flowering phase. This allows beans to let their nuances out and provides the chance for better extraction.

However it is crucial to remember that even a top filter could result in a bad cup of coffee, as the quality of the beans and extraction are essential.

It's here that the magic takes place. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you use to put the grounds of your coffee into while making espresso.

In the steam-driven compact espresso machine machine hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds under high pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

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