How Does Machine Espresso Work?

Machine espresso employs precise pressure and incredible filter technology to produce the perfect cup of coffee. How exactly does it work?

To make an espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.

The Head of the Group

As the name implies the group head is the place you insert your portafilter 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 heads each with its unique advantages and drawbacks. Some are specifically designed for stability of temperature while others are designed to handle pre-infusion. Others are built to control the lever. Some come with a combination of both, like the E61. This is a preferred choice for baristas because it offers multiple benefits in a single package.

As you can see from the above photo the head of the group is fitted with several notches. You can place your portafilter into these notches and twist the head to lock it. There is also a gasket made from rubber that resides inside the notches to help create the seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is essential for a consistent extraction.

In addition to allowing you effortlessly insert your portafilter the group head is also responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket to ensure the temperature is always right for extraction. It is important to remember that even a slight deviation can make the difference between a good and a excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, electric Espresso maker the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure that are required to extract espresso. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive than piston-driven machines and tend to last longer. However, both types of machines can be damaged by excessive use and inadequate cleaning. Pumps are also more complex mechanically, which can raise the cost of even the simplest models.

Certain espresso machines can eliminate the pump completely and instead utilize steam pressure to make espresso. This can lead to over-extraction as the boiler that makes steam also heats the water until it comes to a boil. In addition these machines are often required to restore their pressure between cups, which requires time and energy.

Many espresso machines use the rotary or vibration pump. A vibration model uses a vibrating disk to generate pressure, whereas the rotary model pushes hot water through the ground at a high speed. Both models can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler makes the water warm to the ideal temperature to extract. The steam created will eventually reach the portafilter, which contains the espresso coffee grounds. The steam is then channeled into the cup. The steam creates enough pressure to push the grounds of coffee through. This creates a foam on the top of the espresso. This is one of the main characteristics of a good espresso.

There are three types of espresso machines, each having different types of pumps and brew temperature. There are various ways that the brew may be controlled, as well as the size of the cup that the machine can make.

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

The most commonly used espresso maker is a semiautomatic machine with an Electric Espresso Maker pump. These are the things people think of when they think of an espresso machine. If you have a semi-automatic machine you must grind the beans and then tamp them 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 usually use filters that separate the grounds of the coffee from the hot water. The filter is also an essential component of the machine's temp control, as it helps prevent overheating.

Filters also aid in flavor as it allows for a longer flowering period. This helps the beans release their flavor and gives the chance for better extraction.

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

It's in this area that the magic happens. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is the place where the portafilter (the thingy you put the ground coffee in) is located when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to make steam. The steam then pushes hot water through the coffee grounds under high pressure. These kinds of machines are generally less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect brewing conditions since they 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 been gaining popularity. They make use of an air compressor to force hot water into the ground and are much more mobile than electric steam-driven espresso machines.