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How Does Machine Espresso Work?

The machine espresso utilizes precision pressure, and a filtering technology that is amazing to make the coffee you love. But how exactly does it work?

Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee but the major difference is in the pressure.

The Group Head

As the name implies the group head is the place you place your portafilter when making espresso. It disperses the water into the portafilter, and regulates the pressure of extraction. There are a variety of types of group heads each with its own advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some include a combination like the E61. This is a favorite among baristas as it provides a variety of benefits in a single package.

As you can see in the photo above, the group head has many notches in which you can place your portafilter and twist it manually to secure it. A gasket made of rubber is positioned within the notches to create a seal as you insert your portafilter. The notches on the head allow for an exact position of the portafilter which is necessary for a consistent extraction.

The group head not only allows you to put in your portafilter easily but also maintains the temperature at a constant level. It does this by circulating hot water through the brew container and around the portafilter, making sure that it's always at the correct temperature for extraction. This is vital, because even a small difference in temperature can be the difference between a good and excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure that are required for espresso extraction. This pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being pushed through the ground coffee in the group head.

Pumps tend to be cheaper and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading due to excessive use and poor cleaning. They also make mechanically complex, which can result in a high price tag on even the simplest models.

Certain espresso machines do away with the pump completely and utilize steam pressure to make espresso maker barista. The drawback of this is that the same boiler that produces steam also raises the temperature of the water to the point of boiling, which can lead to excessive extraction. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines employ a vibration or rotary pump, with a vibrating model using a vibrating disc to create the pressure and a rotary model pushing hot water through the grounds at high speed. Both machines can make great espresso however rotary machines tend to be more quiet, durable and less likely to fail.

The Boiler

The boiler is what is used to heat the water to the ideal temperature for extraction. The steam produced will eventually reach the portafilter, which is the container that holds the espresso coffee machines coffee grounds. It is then poured into the cup. In this process, the steam creates pressure and pushes through the grounds of the coffee. This results in a crema on the top of the espresso. This is a hallmark of a great espresso.

There are three distinct types of espresso machines, each having distinct pumps and the temperature of the brew. There are a variety of ways to control the brew as well as the size of the cup that can be produced by the machine.

The first espresso machines were steam-types. They utilized only one boiler to make steam and brew, however the pressure they were able to generate was low - only two bars of atmospheric pressure at most. The coffee tasted bitter and burned. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic espresso machine machine you grind the beans and then tamp them by hand. The pump provides regulated water flow and pressure. This is a great combination of human control and mechanised accuracy.

The Filter

Espresso machines usually have a filter that separates the grounds of coffee from hot water. The filter is also an essential component of the machine's temperature control, as it prevents overheating.

It also enhances flavor, as a filter can allow for a longer bloom time. This allows beans to let their nuances out and provides an opportunity to improve extraction.

It is important to remember that even the best filter can result in a bad cup of coffee. The quality of the beans as well as the extraction, remain vital.

It's here that the magic happens. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you place the portafilter, which is the thingy used to place the coffee grounds in, when making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then pushes hot water through the grounds of coffee under high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. They are however limited to create the ideal 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 been gaining popularity. They use an air-compressor to force hot water through the ground. They are also more mobile than steam-driven electric espresso machines.