How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the delicious coffee we enjoy. How exactly does it work?

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

The Group Head

The group head is the portafilter is inserted when you are making espresso. It disperses water in the portafilter, and then controls the pressure of the extraction. There are a variety of group heads each with its own advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some include a combination such as the E61. This is a very popular choice for baristas since it provides multiple advantages in a single package.

As you can see in the image above, the group head has a number of notches. You place your portafilter into these notches and turn the head around to secure it. There is also a gasket made from rubber in the notches to help create a seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is essential for a consistent extraction.

The group head does not just allow the portafilter to be inserted easily but also maintains an even temperature. This is done by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is constant for extraction. This is important because even a few degrees can make the difference between excellent and great espresso.

The Pump

Unlike manual piston machines, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps that provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee inside the group head.

Pumps are generally 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, which can increase the price of even the simplest models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso machine with grinder. This can result in over-extraction because the boiler that produces steam also heats the water to boil. They also have to constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines utilize a vibration or rotary pump, with a vibrating model using a vibrating disc to create pressure, and a rotary model pushing hot water through the grounds under high speed. Both models are capable of producing excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is the one that makes the water warm to the ideal temperature for extraction. The resulting steam reaches the portafilter which holds the ground espresso and is then pumped down into the cup. In this process, the steam creates pressure that pushes through the grounds of the coffee. This results in a layer crema that is then poured over. This is one of the main characteristics of a great espresso.

There are three kinds of espresso makers. They differ in the type of pump they use and the degree of heat that the espresso is. There are various ways in which the brew could be controlled as well as the dimensions of the cup the machine can make.

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

The most well-known espresso maker is a semi-automatic device that has an electric pump. These are the things people think of when they think of an italian espresso machines maker. If you have a semi-automatic machine you need to grind the beans and then tamp them by hand. However, the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized quality.

The Filter

Espresso machines typically have a filter that separates the coffee grounds from the hot water. The filter is also an essential element of the temperature control system because it stops the machine from overheating.

Filters also aid in flavor because it allows for a longer flowering period. This lets the beans release their nuances, and allows for better extraction.

However it is crucial to keep in mind that even a great filter can result in a poor cup of coffee, because the quality of the beans and extraction is still important.

This is where the magic happens, it's what makes espresso taste good. The grouphead (also called the brewhead) is where you put the portafilter, the device that you use to put the grounds of coffee into 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 pushes hot water into the grounds of coffee at high pressure. They are less expensive and easier for the owner to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to push hot water across the ground, and are more mobile than steam-driven electric espresso machines.