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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the coffee we love. What exactly is it that makes it work?

Espresso is made by forcing hot water under pressure through finely ground coffee. The process is similar to that of making drip coffee. However the pressure is the major difference.

The Group Head

The group head is the portafilter you put in when making espresso. It is responsible for dispersing water into the portafilter and controlling the pressure that results from the extraction. There are a variety of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. Some have a combination of features, such as the E61 that is the standard choice for many baristas due to its ability to offer multiple benefits in one package.

As you can see in the picture above, the group head is equipped with several notches. It is possible to place your portafilter in these notches and then twist the head to secure it. A gasket made of rubber is positioned inside the notches to help make a seal when you insert your portafilter. The notches on the head allow for a precise position of the portafilter which is necessary to ensure an even extraction.

The group head not only allows the portafilter to be inserted easily however it also keeps the same temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is constant for extraction. This is crucial, since even a few degrees can be the difference between a excellent and great espresso.

The Pump

In contrast to piston machines that are manually operated, which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps that provide the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger before being pushed through the ground coffee in the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and inadequate cleaning. They also increase the complexity of mechanical systems that can lead to an expensive price for even the simplest models.

Certain espresso machines can eliminate the pump completely and use steam pressure to brew espresso. The drawback is that the same dual boiler espresso machine that produces steam also raises the temperature of water to boiling, which can lead to excessive extraction. Additionally these machines are often required to rebuild their pressure between cups, which requires time and energy.

Many espresso machines use a rotary or vibration pump. A vibration model uses the vibrating disk to create pressure, whereas the circular model pushes hot liquid through the ground at a fast speed. Both types of machine can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is used to heat the water to the perfect temperature for extraction. The steam created gets to the portafilter which contains the espresso coffee grounds. It is then funneled into the cup. In this process, the steam creates pressure and pushes through the coffee grounds. This results in a crema on top of the espresso. This is one of the main characteristics of a great espresso.

There are three kinds of espresso machines, each with distinct pumps and the temperature of the brew. There are various ways to control the amount of brew, as well as the size of cup that can be made by the machine.

The first espresso machines were steam-type. The first espresso machines were steam-type machines. The coffee tasted bitter and burned. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp your beans yourself, but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and mechanized quality.

The Filter

Espresso machines typically use a filter that separates the coffee grounds from the hot water. The filter is also a vital part of the temperature control system, as it keeps the machine from overheating.

Filters also aid in flavor because it allows for a longer flowering phase. This lets the beans let their nuances out, and improves extraction.

However it is crucial to remember that even a great filter could result in a bad cup of coffee, because the quality of the beans and extraction is still important.

It's here that the magic takes place. This is the reason why mini espresso machine tastes so good. The grouphead, also referred to as the brew head, is the place where the portafilter (the thingy you put the coffee grounds into) is placed when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight container to create steam, which is then pushed through the grounds with High end espresso machine pressure. These kinds of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited to create the perfect brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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