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How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the coffee we love. What exactly is it?

To make an espresso machines for home, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However, the pressure is the major difference.

The Head of the Group

As the name suggests the group head is where you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure that results from the extraction. There are various kinds of group heads each with its particular advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some come with a combination of both, such as the E61. This is a very popular choice for baristas as it provides a variety of benefits in a single package.

As you can see in the photo above the head of the group has a number of notches. You can place your portafilter into these notches and twist the head to secure it. A gasket made of rubber is placed in the notches to create a seal as you insert your portafilter. The notches on the head allow for an exact positioning of the portafilter which is vital for an efficient extraction.

In addition to allowing you easily insert your portafilter, the group head is also responsible for maintaining an even temperature. It does this by circulating hot water through the brew container and around the portafilter to ensure that it is always at the right temperature to extract. It is important to remember that even a small difference can make the difference between a decent and a great espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure necessary to extract espresso. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger prior being shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven machines and tend to last longer, although both types of machines may become damaged due to excessive use and poor cleaning. Pumps are also more complex mechanically, and can add to the price of even the simpler models.

Certain espresso machines can eliminate the pump completely and use steam pressure to brew espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of the water to the point of boiling which could lead to excessive extraction. The machines must also continuously rebuild their pressure between cups. This takes energy and time.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model uses an oscillating disk to create pressure, whereas the rotating model pushes hot water through the ground at a high speed. Both types of machines can make a great espresso, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the element that heats the water to the ideal temperature for extraction. The steam created is then directed to the portafilter, which holds the espresso grounds. The steam is then channeled into the cup. During this process, the steam creates pressure to push through the coffee grounds. This creates a foam on the top of the espresso. This is the hallmark of a great espresso.

There are three kinds of buy espresso makers (Www.instapaper.com) machines, each having distinct pumps and brew temperature. There are a variety of ways to control the brew as well as the size of cup that can be made by the machine.

The earliest espresso machines were steam types. They employed a single boiler to make steam and brew, however, the pressure they could produce was not very high - two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. The modern discount espresso machines machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines espresso, they envision these machines. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand, but the pump provides regulated water flow and pressure. This is a great solution that combines human control with mechanised accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also a crucial component of the temperature control system because it stops the machine from overheating.

A filter also improves flavor, as it permits a longer flowering period. This allows the beans to release their flavors, and also allows for better extraction.

It is important to remember that even the most efficient filter can produce a bad cup of coffee. The quality of the beans, and the extraction, are still very important.

It's here that the magic takes place. This is what makes espresso taste so delicious. The grouphead (also called the brewhead) is where you place the portafilter - the thingy that you use to put the coffee grounds into, when making espresso.

In a steam-driven espresso machine hot water is heated in an airtight container to create steam. This is then pushed through the grounds at high pressure. These kinds of machines tend to be cheaper and easier to maintain than pumps-driven models. However, they are limited in their ability to create the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.

In recent times, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to force hot water through grounds and are much more portable than electric steam-driven machines.