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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly does it work?

In order to make espresso, hot water is pushed under 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

As the name implies, the group head is where you put your portafilter in when brewing espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure that results from the extraction. There are a variety of types of group head each with its unique advantages and disadvantages. Some are specifically designed for temperature stability while others are built to handle pre-infusion. Some are designed to control the lever. Some include a combination like the E61. This is a favorite among baristas due to the fact that it has multiple benefits in a single package.

As you can see in the photo above the group head is made up of several notches where you place your portafilter and twist it with your hands to secure it. There is also a gasket of rubber that is a part of the notches and helps create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for a precise position of the portafilter which is vital to ensure a consistent extraction.

Aside from allowing you to easily insert your portafilter, the group head is also responsible to maintain an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is constant for extraction. This is important, as even a small difference in temperature can mean the difference between excellent and great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure needed for espresso extraction. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven models, and they tend to last longer. However, both types of machines can get damaged through overuse and lack of cleaning. They also add mechanical complexity that can lead to costly prices for even the simplest models.

Some commercial espresso machine machines employ steam pressure instead of a pump to make espresso. This can lead to over-extraction as the boiler that produces steam also causes the water to boil. In addition the machines often have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines use an rotary or a vibration pump. A vibration model uses a vibrating disk to generate pressure, whereas the rotating model pushes hot water through the ground at high speed. Both machines can produce excellent espresso however rotary machines tend to be quieter, more durable and less likely to break.

The Boiler

The boiler is the component that heats water to the ideal temperature to extract. The resulting steam reaches the portafilter containing ground espresso beans and gets funnelled down into the cup. The steam generates enough pressure to push the coffee grounds through. This results in a layer of crema that is then poured over. This is one of the main characteristics of a great espresso.

There are three kinds of espresso makers, Machine Espresso which differ in the type of pump they use and Machine Espresso the degree of heat that the brew is. There are various ways to control the brew as well as the size of the cup that can be made by the machine.

The earliest espresso machines were steam-based. The earliest espresso machines were steam-type machines. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker for home maker is a semiautomatic machine that has an electric pump. These are the things people think of when they think of an espresso machine. If you have a semi-automatic machine you have to grind the beans and then tamp them by hand. The pump provides regulated water flow and pressure. This is an excellent compromise between human touch and mechanized consistency.

The Filter

Typically, espresso machines utilize a filter to separate out the coffee grounds as they pass through the hot water. The filter is also a vital component of the machine's temperature control, as it prevents overheating.

It also improves flavor, since a filter allows for a more prolonged bloom time. This allows the beans to release their flavors, and improves extraction.

However it is crucial to remember that even a good filter can produce a bad cup of coffee, since the quality of the beans and extraction is important.

This is where the magic happens. It's what makes an espresso really taste good. The grouphead, also referred to as the brew head, is the place where the portafilter (the device you put the ground coffee into) is placed when making espresso.

Steam-driven espresso machines make use of hot water that is heated inside an airtight container to create steam. The steam then pushes hot water into the grounds of coffee at high pressure. These machines are cheaper and easier to maintain than pumps-driven models. However, they are limited in their ability to produce the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.

In recent years, compressed air-driven espresso machines have been gaining popularity. They use an air compressor to push hot water across the ground. They are also more mobile than electric steam-driven espresso machines.