How Does Machine Espresso Work?

Machine espresso uses precision pressure and amazing filter technology to make the perfect cup of coffee. But how exactly does it work?

Espresso is produced by pushing hot water under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, it is the pressure that makes the main difference.

The Group Head

As the name implies, the group head is the place you place your portafilter while brewing espresso. It disperses water into the portafilter, and regulates the pressure of extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are specifically designed for stability in temperature, while others are designed to handle pre-infusion. Others are made to control the lever. Some come with a combination of both, like the E61. This is a favorite among baristas due to the fact that it has multiple benefits in one package.

As you can see in the above image the group head comes with numerous notches that you can put your portafilter, then twist it with your hands to secure it. A gasket of rubber is situated inside the notches, which helps create a seal while you insert your portafilter. The notches on the head permit an exact position of the portafilter which is essential for a consistent extraction.

In addition to allowing you to easily connect your portafilter, the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew container and Compact Espresso Machine around the portafilter to ensure that it is always at the right temperature for extraction. This is vital, because even a few degrees can be the difference between a excellent and great espresso.

The Pump

The motorized pumps used in espresso machines that rotate provide the nine atmospheric bar pressure that is required to extract espresso. This differs from manual piston machines which use levers. The pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.

Pumps are generally more affordable and last longer than piston-driven machines. However, both types of machines may degrade due to excessive use and insufficient cleaning. Pumps are also more complicated mechanically, which could increase the cost of even most basic models.

Some espresso machines can eliminate the pump completely and make use of steam pressure to make espresso. The disadvantage of this is that the same boiler that produces steam also raises the temperature of the water to the point of boiling which can cause over-extraction. These machines also have to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines employ the rotary or vibration pump, with a vibration model using a rotating disc to create the pressure, and rotating models that push hot water through the grounds at high speed. Both machines can produce excellent espresso, but rotary machines are quieter, more durable and less likely to fail.

The Boiler

The boiler is the component that heats water to an ideal temperature to extract. The resultant steam then reaches the portafilter containing ground espresso beans and is then pumped down into the cup. In this process, the steam creates pressure and pushes through the coffee grounds. This creates a foam on top of the espresso. This is one of the main characteristics of a good espresso.

There are three different types of espresso machines, each having distinct pumps and the temperature of the brew. There are different ways to control the brew and the size of cup that can be made by the machine.

The earliest espresso machines were steam type. The first espresso machines were steam types. This led to the coffee tasting burnt and bitter. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the water flow and pressure. This is a fantastic solution that combines human control with mechanised reliability.

The Filter

Typically, espresso machines uk machines espresso utilize filters that separate the grounds of coffee when they pass through the hot water. The filter is also a crucial part of the temperature control system, as it keeps the machine from overheating.

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

However, it is important to remember that even a high-quality filter can result in a poor cup of coffee, because the quality of the beans and extraction are crucial.

This is where the magic happens, it's what makes an espresso machines home really taste good. The grouphead (also known as the brewhead) is where you place the portafilter - the thingy used to place the grounds of your coffee into when making espresso.

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

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