10 Quick Tips About Machine Espresso

How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the delicious coffee we enjoy. What exactly is it that makes it work?

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

The Head of the Group

The name implies the group head is the place you place your portafilter while brewing espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the extraction. There are several different types of group head each with its particular advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. There are even some that have a combination of features, like the E61 one, which is the classic choice among many baristas because of its ability to offer multiple benefits in one package.

As you can see in the above photo the group head is equipped with several notches. It is possible to place your portafilter into these notches and twist the head to secure it. A rubber gasket is located inside the notches to help make a seal when you insert your portafilter. The notches on the head allow for an exact position of the portafilter which is necessary to ensure an even extraction.

In addition to allowing you to easily place your portafilter in, the group head is also responsible for maintaining an even temperature. It does this by cycling hot water through the brew pan and around the portafilter to ensure that it's always at the right temperature to extract. This is important, as even a small espresso machine difference in temperature can make the difference between a good and great espresso.

The Pump

Contrary to manual piston machines which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure needed for espresso extraction. The pressure is built by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven machines, and they tend to last longer, but both types of machines can get damaged through overuse and lack of cleaning. They also increase the complexity of mechanical systems that can lead to the cost of even the most basic models.

Certain espresso machines remove the pump completely and instead use steam pressure to brew espresso. This can cause over-extraction because the boiler that makes steam also causes the water to boil. Additionally these machines typically have to restore their pressure between cups, which takes time and energy.

Many espresso machines utilize a vibration or rotary pump, which has a vibration model using a vibrating disc to create the pressure, and a rotary model pushing hot water through the grounds under high speed. Both models are capable of producing excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is the element which heats the water to the ideal temperature to extract. The steam produced is then directed to the portafilter, which is a container for espresso grounds. It is then funneled into the cup. The steam creates enough pressure to push the coffee grounds through. This creates a layer crema that is then poured over. This is the hallmark of a great espresso.

There are three kinds of espresso machines, each with different types of pumps and brew temperature. There are different ways that the brew can be controlled, as well as the size of the cup the machine is capable of making.

The earliest espresso machines were steam-based. They used one boiler to make steam and Best Portable Espresso Maker brew, however, the pressure they could generate was low - only two bars of atmospheric pressure, at most. The coffee tasted bitter and burnt. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most popular espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine you must grind the beans and then tamp them by hand, but the pump controls the flow of water and pressure. This is a great compromise between human control and mechanized accuracy.

The Filter

Espresso machines usually use filters that separate the grounds of the coffee from the hot water. The filter is also a vital component of the machine's temp control, since it stops overheating.

It also helps with flavor, as a filter lets you enjoy a longer bloom time. This lets the beans release their flavors, and improves extraction.

It is important to keep in mind that even the Best Portable Espresso Maker filter can result in a bad cup of coffee. The quality of the beans, and the extraction process are still very important.

This is where the magic happens, it's what makes espresso taste great. The grouphead (also called the brewhead) is where you put the portafilter, the thingy that you put the coffee grounds in, while making espresso.

In a steam-driven espresso machine hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at a high pressure. These kinds of machines tend to be cheaper and easier to maintain than pump-driven models. They are however limited for creating the ideal 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 a compressed air pump 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.