How Does Machine Espresso Work?

Machine espresso machine coffee utilizes precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. How does it work exactly?

In order to make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee for espresso machine but the major difference is in the pressure.

The Group Head

As the name implies, the group head is where you put your portafilter in when making espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some focus 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 popular choice among baristas because it offers multiple benefits in a single package.

As you can see in the photo above The group head features many notches in which you can place your portafilter and twist it with your hands to lock it in. A gasket made of rubber is positioned within the notches to make a seal when you insert your portafilter. The notches permit precise placement of the portafilter. This is vital for an accurate extraction.

In addition to allowing you easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew basket and around the portafilter to ensure that it is always at the correct temperature to extract. This is important, as even a small difference in temperature can mean the difference between good and great espresso.

The Pump

The motorized pumps that are used in rotary cheap espresso machine machines supply the nine atmospheric bars of pressure required for espresso extraction. This is different from manual piston machines that use levers. The pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can deteriorate because of excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which can increase prices of even simple models.

Some espresso machines use steam pressure instead of a pump to make espresso. The downside is that the same boiler that produces steam also raises the temperature of water to the point of boiling, which can lead to over-extraction. Additionally the machines often have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines employ a vibration or rotary pump, with a vibration model that uses a vibrating disc to generate the pressure and a rotary model pushing hot water through the grounds under high speed. Both machines produce great espresso however rotary machines tend to be quieter, more durable and less likely to break.

The Boiler

The boiler is the one that will heat the water to the right temperature for extraction. The steam created reaches the portafilter, which is a container for espresso grounds. It is then funneled into the cup. The steam causes enough pressure to push the grounds of coffee through. This creates a crema on the top of the espresso. This is one of the main characteristics of a good espresso.

There are three different types of espresso coffee machine machines, each having a different type of pump and the temperature of the brew. There are also different ways in which the brew can be controlled and the size of the cup the machine can make.

The first espresso machines were steam-types. They employed only one boiler to make both brew and steam, however, the pressure they could generate was low - only two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic model with an electric pump. These are what people imagine when they think of an espresso machine. With a semi-automatic espresso machine, you must grind the beans and tamp them by hand. The pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and mechanized accuracy.

The Filter

Typically, espresso machines utilize filters to separate the grounds of the coffee as they go through the hot water. The filter is also an essential part of the machine's temperature control, as it helps prevent overheating.

A filter also improves flavor as it allows for an extended flowering time. This helps the beans to let their nuances out and provides an opportunity to improve 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 is still vital.

This is where the magic happens. It's what makes an espresso really taste good. The grouphead (also known as the brewhead) is where you place the portafilter, the device which you put the coffee grounds in, when making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight container to produce steam. The steam then pushes hot water through grounds of coffee at high pressure. These types of machines are usually less expensive and simpler to maintain than pump-driven models. They are however limited in their ability to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

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