Maisie Birdwood

How Does Machine Espresso Work?

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

To make an espresso makers hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the major difference.

The Head of the Group

The group head is the portafilter you put in when making espresso. It is responsible for dispersing the water into the portafilter and controlling the pressure of the extraction. There are many different types of group heads, each with its own advantages and disadvantages. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. There are also some that contain a variety of features, like the E61, which is considered the classic choice among many baristas due to its capacity to provide multiple benefits in one package.

As you can see in the image above the group head is made up of several notches where you put your portafilter, then twist it by hand to lock it in. A gasket made of rubber is placed within the notches to create a seal as you insert your portafilter. The notches permit precise placement of the portafilter. This is crucial for an even extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is also responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter, and through the brew basin, ensuring the temperature is always right for extraction. This is important because even a few degrees can mean the difference between good and excellent espresso.

The Pump

The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bar pressure that is required to extract espresso coffee machine for home. This is different from manual piston machines that use a lever. The pressure builds up by drawing 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 than piston-driven machines and tend to last longer, however both types of machines may degrade with overuse and insufficient cleaning. They also increase the complexity of mechanical systems that can lead to costly prices for even the most basic models.

Some mini Espresso maker machines eliminate the pump completely and employ steam pressure to create espresso. This can cause over-extraction because the boiler that makes steam also warms the water to boil. Additionally, these machines frequently have to restore their pressure between cups, which requires time and energy.

Many espresso machines utilize the rotary or vibration pump, with a vibration model using a vibrating disc to create the pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines can make great espresso, however rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is the one that will heat the water to the perfect temperature for extraction. The resulting steam is then transferred to the portafilter that contains ground espresso beans and is then pumped down into the cup. During this process, the steam creates pressure that pushes through the grounds of the coffee. This creates a crema on top of the espresso. This is a hallmark of a good espresso.

There are three distinct types of travel espresso maker machines, each having distinct pumps and brew temperature. There are different ways in which the brew could be controlled as well as the size of the cup the machine can produce.

The first espresso machines were steam-types. They utilized one boiler to make both steam and brew but the pressure they could produce was not very high - two bars of atmospheric pressure at the most. The coffee and espresso machine tasted bitter and burned. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semi-automatic machine that has an electric pump. These are the images people have when they think of an espresso maker. If you have a semi-automatic machine you must grind the beans and tamp them by hand. The pump provides regulated water flow and pressure. This is a great combination of human control and mechanised accuracy.

The Filter

Typically, espresso machines utilize filters that separate the grounds of coffee as they move through the hot water. The filter is also a vital component of the machine's temp control, since it stops overheating.

A filter also helps with flavor as it allows for a longer flowering period. This lets the beans let their nuances out, and allows for better extraction.

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

This is where the magic happens. It's what makes an espresso really taste good. The grouphead, often referred to as the brew head, is the place where the portafilter (the container you place the ground coffee into) is located when you're 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 the grounds of coffee under high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pump-driven models. However, they are limited in their ability to produce the ideal brewing conditions, because they operate at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bar.

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