How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly does it work?

Espresso is made by pushing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee but the major difference is in the pressure.

The Head of the Group

As the name implies, the group head is where you insert your portafilter when brewing espresso maker barista. It is responsible for dispersing water into the portafilter, and controlling the pressure of the resulting 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 come with a combination of both, like the E61. This is a preferred choice for baristas as it provides a variety of benefits in a single package.

As you can see in the above image The group head features numerous notches that you can place your portafilter before twisting it manually to secure it. There is also a gasket of rubber that resides inside the notches to help create a seal when you insert your portafilter into the machine. The notches permit precise placement of your portafilter. This is vital for an efficient extraction.

The group head is not just able to allow you to insert your portafilter easily however it also keeps a constant temperature. It does this by circulating hot water through the brew pan and around the portafilter to ensure that it is always at the correct temperature for extraction. This is vital, because even a few degrees can make the difference between a excellent and great espresso.

The Pump

In contrast to manual piston machines which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure necessary to extract espresso. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven machines, and tend to last longer. However, both types of machine can be damaged by excessive use and inadequate cleaning. Pumps are also more complicated mechanically, and can add to the cost of even the most basic models.

Some espresso machines use steam pressure instead of a pump to brew espresso. The disadvantage 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 in between cups. This takes energy and time.

A majority of espresso machines utilize an rotary or a vibration pump. A vibration model makes use of the vibrating disk to create pressure, whereas the Rotary model pushes hot coffee through the ground at a rapid speed. Both machines can make great espresso, but rotary machines are quieter, more durable and less likely to fail.

The Boiler

The boiler is what heats the water to a temperature that is ideal for extraction. The steam that is produced gets to the portafilter which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This creates a crema on the top of the espresso. This is the hallmark of a great espresso.

There are three distinct types of espresso machines, each with different pumps and the temperature of the brew. There are different ways in which the brew could be controlled and the dimensions of the cup the machine can produce.

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

The most common espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the water flow and pressure. This is a great compromise between the human touch and mechanized accuracy.

The Filter

Typically, espresso machines employ filters to separate the grounds of coffee when they pass through the hot water. The filter is also a vital part of the temperature control system, as it prevents the machine from overheating.

It also helps with flavor as a filter allows for a more prolonged bloom phase. This lets the beans release their flavor and allows for a better extraction.

However it is crucial to keep in mind that even a great filter can make a terrible cup of coffee as the quality of the beans and extraction are important.

This is where the magic happens. It's what makes espresso coffee machine with milk frother taste good. The grouphead (also called the brewhead) is where you place the portafilter, the device that you put the coffee grounds into, when making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water through grounds of coffee at high pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent times, espresso machines powered by a compressed air compressor have become increasingly popular. They use an air-compressor to force hot water through the ground and are much more mobile than steam-driven electric espresso machines.