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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the coffee we love. How exactly does it work?

Espresso is made by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.

The Group Head

As the name suggests the group head is where you insert your portafilter when making espresso. It disperses water in the portafilter and controls the pressure of the extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. There are even some that have a combination of features, such as the E61, which is considered the classic choice among many baristas due to its ability to offer multiple benefits in one package.

As you can see from the above photo the head of the group has a number of notches. The portafilter is placed into these notches and turn the head around to secure it. A rubber gasket is located inside the notches to help create a seal when you insert your portafilter. The notches on the head allow for an exact position of the portafilter which is vital for an efficient extraction.

Aside from allowing you to easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew pan and around the portafilter to ensure that it is always at the correct temperature to extract. This is vital, because even a few degrees can make the difference between good and great barista espresso machine.

The Pump

In contrast to piston machines that are manually operated, that use a lever to pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure required to extract espresso. This pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.

Pumps tend to be less expensive than piston-driven models, and they tend to last longer, although both types of machines may degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, which can raise prices of even simplest models.

Some espresso machines use steam pressure instead of a pump to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water to boiling, which can lead to excessive extraction. The machines must also constantly rebuild their pressure between cups. This requires energy and time.

Many espresso machines use the rotary or vibration pump. A vibration model utilizes a rotating disk to generate pressure, whereas the rotary model pushes hot water through the ground at a rapid speed. Both machines produce great espresso but rotary machines are more stable, quieter and less likely to break.

The Boiler

The boiler is what makes the water warm to the ideal temperature for extraction. The resulting steam reaches the portafilter containing the ground espresso coffee, and gets funnelled down into the cup. In this process, the steam creates pressure to push through the coffee grounds. This produces a layer of crema that is then poured over. This is the hallmark of a good espresso.

There are three types of espresso makers, and they differ in the kind of pump they use and how hot the brew is. There are various ways in which the brew could be controlled, as well as the size of the cup that the maker can create.

The first espresso machines were steam-types. The earliest espresso machines were steam-type machines. This led to the coffee tasting burnt and bitter. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso machine is a semiautomatic with an electric pump. These are the images people have when they imagine an Cafe Espresso Machine (Bookmarkhard.Com) machine. With a semi-automatic machine, you grind the beans and tamp them by hand. However, the pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized quality.

The Filter

Typically, travel espresso maker machines employ a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also a vital part of the machine's temperature control, as it helps prevent overheating.

It also aids in flavor, as a filter lets you enjoy a longer bloom time. This allows the beans to release their flavor and allows for better extraction.

However it is crucial to remember that even a great filter can result in a poor cup of coffee as the quality of the beans and extraction is essential.

This is where the magic happens. It's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy which you put the coffee grounds in, when making espresso.

In the steam-driven espresso machine hot water is heated in an airtight container bean to cup espresso machine produce steam, which then pushes the hot water through the grounds at high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, compressed-air-pump-driven espresso machines have become more popular. They utilize an air compressor to push hot water through grounds and are much more portable than steam-driven electric machines.