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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?

In order to make espresso hot water is pushed under pressure through finely best ground coffee for espresso machine coffee. The process is similar to that of making drip coffee. However the pressure is the major difference.

The Group Head

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 of the resulting extraction. There are many different kinds of group head, each with their own advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. There are also some that include a mix of features, such as the E61 one, which is the standard choice for many baristas for its ability to provide multiple benefits in a single package.

As you can see in the image above The group head features many notches in which you can place your portafilter before twisting it by hand to secure it. A gasket made of rubber is positioned in the notches to create a seal when you insert your portafilter. The notches on the head permit an exact position of the portafilter which is crucial for a consistent extraction.

In addition to allowing you to easily connect your portafilter, the group head is also responsible for maintaining a consistent temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is at the right level for extraction. It is important to realize that even a small deviation can make the difference between a good and excellent espresso.

The Pump

The motorized pumps used in rotary best espresso machine under 200 machines provide the nine atmospheric bar pressure that is required to extract espresso. This is different from manually operated piston machines that employ a lever. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are generally cheaper and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading due to overuse and insufficient cleaning. They also make mechanically complex which can result in an expensive price for even the most basic models.

Some espresso machines remove the pump completely and use steam pressure to brew espresso maker for home. This can result in over-extraction because the boiler that produces steam also warms the water to boil. The machines must also continuously rebuild their pressure between cups. This takes energy and time.

Many retro espresso machine machines make use of either a rotary or vibration pump, with a vibrating model that uses a vibrating disc to generate the pressure and the rotary model pushing hot water through the grounds under high speed. Both machines can make great espresso however rotary machines tend to be more quiet, durable and less likely to break down.

The Boiler

The boiler makes the water warm to a temperature that is ideal to extract. The resulting steam is then transferred to the portafilter, which contains ground espresso beans and gets funnelled down into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This results in a crema on the top of the espresso machine with frother. This is one of the main characteristics of a good espresso.

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

The earliest espresso machines were steam type. They employed a single boiler to make both steam and brew but the pressure they could produce was very low - just two bars of atmospheric pressure at most. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the water flow and pressure. This is a great compromise between human control and mechanised consistency.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also a vital component of the machine's temp control, as it prevents overheating.

A filter also helps with flavor as it allows for a longer flowering period. This allows beans to release their nuances and gives an opportunity for better extraction.

However, it is important to keep in mind that even a good filter could result in a bad cup of coffee as the quality of the beans and extraction are vital.

It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead, often called the brew head, is where the portafilter (the thingy you put the ground coffee into) is placed when making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to make steam. The steam then moves hot water through the grounds of the coffee under pressure. These types of machines are usually less expensive and simpler to maintain than pumps-driven models. They are however limited in their ability to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They use an air compressor to force hot water into the ground, and are more mobile than steam-driven electric espresso machines.