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How Does Machine Espresso Work?

The machine espresso makes use of precision pressure, and filtering system that is awe-inspiring to make the coffee you enjoy. What exactly is it?

Espresso is made by pushing hot water at high pressure through finely ground coffee espresso machines. The process is similar to making drip coffee, however the main difference lies in the pressure.

The Group Head

As the name suggests the group head is the place you place your portafilter when brewing espresso. It is responsible for dispersing water into the portafilter before controlling the pressure of the resulting extraction. There are many different types of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas as it provides a variety of advantages in one package.

As you can see in the image above the group head comes with many notches in which you can place your portafilter and then twist it with your hands to secure it. A gasket of rubber is situated in the notches to create a seal while you insert your portafilter. The notches on the head allow for an exact positioning of the portafilter which is crucial for an even extraction.

The group head does not just allow you to insert your portafilter easily however it also keeps 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 vital, because just a few degrees could make the difference between a good and excellent espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure that are required for buy espresso machine extraction. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger before being shot through the ground coffee inside the group head.

Pumps tend to be cheaper than piston-driven machines and tend to last longer, although both types of machine can become damaged 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 entirely and make use of steam pressure to make espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. They also have to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines make use of the rotary or vibration pump, with a vibration model that uses a vibrating disc to create the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both types of machines can produce an excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what makes the water warm to the perfect temperature for extraction. The steam produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then poured into the cup. During this process, the steam causes pressure to push through the grounds of the coffee. This creates a foam on the top of the espresso. This is one of the hallmarks of a great espresso.

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

The earliest espresso machines were steam type. They utilized one boiler to make both brew and steam, however, the pressure they could produce was very low - just two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used espresso machine is a semiautomatic model with an electric pump. This is what people envision when they think of an espresso maker. If you have 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 mechanized consistency.

The Filter

Typically, espresso machines have filters bean to cup espresso machine separate the grounds of coffee when they pass through the hot water. The filter is also an important element of the temperature control system, because it stops the machine from overheating.

Filters also aid in flavor as it allows for the beans to flower for a longer period of time. This allows the beans to release their flavors, and allows for better extraction.

However it is crucial to keep in mind that even a top filter can make a terrible cup of coffee, because the quality of the beans and extraction is crucial.

This is where the magic happens. It's what makes espresso taste great. The grouphead, sometimes called the brew head, is where the portafilter (the container you place the ground coffee in) is placed when making espresso.

In an best home espresso machine machine that is driven by steam, hot water is heated in an airtight container to create steam, which is then pushed through the grounds at a high pressure. These kinds of machines tend to be cheaper and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

In recent years, espresso coffee machine with milk frother machines powered by compressed air-pump are becoming increasingly popular. They use an air-compressor to push hot water across the ground, and are more mobile than steam-driven electric espresso machines.