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How Does Machine Espresso Work?

The machine espresso is made using precision pressure, and filter technology that is awe-inspiring to create the coffee you enjoy. What exactly is it?

To make an espresso hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, it is the pressure that makes the main difference.

The Group Head

The name implies the group head is the place you place your portafilter when brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure that results from the extraction. There are various kinds of group heads, each with their unique advantages and drawbacks. Some are focused on temperature stability, while others on pre-infusion capabilities, while others are designed to control the lever. Some include a mix of features, such as the E61, which is considered the standard choice for many baristas for its ability to offer multiple perks in a single package.

As you can see in the above image the group head is made up of many notches in which you can place your portafilter and twist it manually to lock it in. There is also a gasket made from rubber that resides inside the notches and helps create a seal when you insert your portafilter into the machine. The notches permit precise placement of the portafilter. This is crucial to ensure an efficient extraction.

Aside from allowing you to easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is at the right level to extract the coffee. It is important to remember that even a small differences can make the distinction between a good and great espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure that are required for espresso extraction. The pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger before it is shot through the ground coffee inside the group head.

Pumps are typically less expensive than piston-driven machines, and tend to last longer, but both types of machines could get damaged through overuse and lack of cleaning. They also create mechanical complexity that can lead to an expensive price for even the simplest models.

Certain espresso machines remove the pump completely and make use of steam pressure to make barista espresso machine. The drawback is that the boiler that produces steam also increases the temperature of the water to boiling which could lead to over-extraction. Additionally these machines are often required to restore their pressure between cups, which requires time and energy.

Many espresso machines utilize either a rotary or vibration pump, which has a vibration model using a vibrating disc to create the pressure and the rotary model pushing hot water through the grounds at high speed. Both types of machines are capable of producing excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the part that heats the water to the optimal temperature for extraction. The steam created reaches the portafilter, which holds the espresso grounds. It is then pumped into the cup. The steam generates enough pressure to push the grounds of the coffee through. This results in a layer of crema on top. This is one of the hallmarks of a great espresso.

There are three different types of espresso machines (mixup.Wiki), each having different types of pumps and the temperature of the brew. There are many ways to control the strength of the brew and the size of the cup that can be made by the machine.

The first espresso machines were steam-based. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic that has an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine you need to grind the beans and tamp them by hand. The pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized quality.

The Filter

Typically, espresso machines employ a filter to separate out the grounds of coffee as they move through the hot water. The filter is also a crucial element of the temperature control system because it stops the machine from overheating.

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

It is important to keep in mind that even the most efficient filter can result in a bad cup of coffee. The quality of the beans, and the extraction, remain vital.

This is where the magic happens, it's what makes espresso taste good. The grouphead (also called the brewhead) is where you place the portafilter - the thingy that you use to put the grounds of your coffee into when making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight container to create steam. The steam then pushes hot water through the grounds of the coffee under pressure. These kinds of machines are usually less expensive and easier to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal brewing conditions, since they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

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