How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to make the coffee we love. But how exactly does it work?

Espresso is made by forcing hot water under 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 is inserted when you are making espresso. It disperses water into the portafilter, and then regulates the pressure of the extraction. There are various kinds of group head, each with their unique advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. There are some that come with a range of features, like the E61, which is considered the classic choice among many baristas for its ability to offer multiple perks in a single package.

As you can see in the above image The group head features numerous notches that you can put your portafilter, then twist it manually to lock it in. There is also a gasket of rubber in the notches to help create an airtight seal after inserting your portafilter into the machine. The notches permit an exact placement of the portafilter. This is vital for an even extraction.

Aside from allowing you to easily connect your portafilter, the group head is also responsible to maintain an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is always at the right level for extraction. This is important, as even a few degrees can mean the difference between good and excellent espresso.

The Pump

In contrast to manual piston machines which rely on a lever that pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are generally cheaper and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to overuse and inadequate cleaning. They also increase the complexity of mechanical systems and can lead to costly prices for even the most basic models.

Some espresso machines can eliminate the pump completely and employ steam pressure to create espresso. This could lead to over-extraction since the boiler that produces steam also heats the water to boil. They also have to continuously rebuild their pressure between cups. This requires energy and time.

A large majority of espresso machines employ either a vibration or rotary pump. A vibration model uses an oscillating disk to create pressure, whereas a Rotary model pushes hot coffee through the ground at a fast speed. Both machines produce great espresso, however rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler is the component that heats water to the optimal temperature to extract. The resulting steam is then transferred to the portafilter containing ground espresso beans and is then funneled down into the cup. The steam creates enough pressure to push the grounds of coffee through. This results in a whipped-up the top of the espresso. This is a hallmark of a good espresso.

There are three types of espresso makers, which differ in the kind of pump they use and how hot the brew is. There are a variety of ways in which the brew could be controlled and the dimensions of the cup the machine is capable of making.

The first barista espresso coffee machine machines were steam-type. The first espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso machine is a semiautomatic with an electric pump. These are what people imagine when they imagine an Italian Espresso Machine machine. If you have a semi-automatic machine you have to grind the beans and then tamp them by hand. However, the pump controls the flow of water and pressure. This is a great compromise between the human touch and mechanized consistency.

The Filter

Typically, espresso machines utilize filters to separate the grounds of coffee when they pass through the hot water. The filter is also a vital component of the machine's temperature control, as it prevents overheating.

A filter can also help with flavor as it allows for an extended flowering time. This helps the beans release their flavor and gives an opportunity to improve extraction.

It is important to remember that even the best espresso machine under 200 filter can make a bad cup of coffee. The quality of the beans and the extraction, remain vital.

This is where the magic happens, it's the thing that makes espresso taste good. The grouphead, also called the brew head, is the place where the portafilter (the thingy you put the coffee ground into) is placed when making espresso.

Steam-driven small espresso machine machines use hot water that is heated in an airtight container to create steam. The steam then moves hot water through the grounds of coffee under high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal conditions for brewing since they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, compressed air-driven espresso machines have become more popular. They utilize an air compressor to force the hot water through the grounds, and are far more portable than steam-driven electric machines.