How Does Machine Espresso Work?

The machine espresso utilizes precision pressure, and filter technology that is mind-blowing to make the coffee you enjoy. How exactly does it work?

To make an espresso hot water is pushed 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 name implies the group head is where you place your portafilter when brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the extraction. There are many different kinds of group head each with its particular advantages and disadvantages. Some focus on temperature stability, while others on pre-infusion capabilities, and still others are designed to control the lever. Some have a combination, like the E61. This is a very popular choice for baristas due to the fact that it has multiple benefits in one package.

As you can see in the photo above The group head features several notches where you put your portafilter, then twist it with your hands to lock it in. A gasket of rubber is situated inside the notches to help create a seal when you insert your portafilter. The notches on the head permit an exact positioning of the portafilter which is vital to ensure a consistent extraction.

Aside from allowing you to easily insert your portafilter, the group head is also responsible for maintaining an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is constant for extraction. This is important because even a few degrees can make the difference between good and excellent espresso.

The Pump

The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bars of pressure required to extract espresso. This differs from manual piston machines that rely on levers. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee inside the group head.

Pumps are generally less expensive and last for longer than piston-driven machines. However, both kinds of machines can deteriorate because of frequent use and inadequate cleaning. They also increase the complexity of mechanical systems, which can result in costly prices for even the most basic models.

Some espresso machines can eliminate the pump completely and instead make use of steam pressure to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water until it reaches boiling which can cause excessive extraction. Additionally these machines typically have to restore their pressure between cups, which takes time and energy.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model makes use of a rotating disk to generate pressure, whereas a rotating model pushes hot water through the ground at high speed. Both types of machines can make excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is what will heat the water to a temperature that is ideal for extraction. The steam that is produced reaches the portafilter, which contains the ground espresso coffee and is then pumped into the cup. The steam creates pressure to push through the coffee grounds. This results in a layer of crema on top. This is one of the hallmarks of a great espresso coffee machine with milk frother (click the following article).

There are three different types of espresso machines, each with different types of pumps and the temperature of the brew. There are also different ways in which the brew could be controlled and the dimensions of the cup the machine can make.

The earliest espresso machines were steam types. They utilized a single boiler to make both steam and brew however the pressure they were able to generate was low - only two bars of atmospheric pressure, at most. This led to the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans yourself while the pump controls the water flow and pressure. This is a great compromise between the human touch and the mechanized quality.

The Filter

Typically, espresso machines utilize a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an important element of the temperature control system as it keeps the machine from overheating.

It also improves flavor, since a filter allows for a longer bloom time. This lets the beans release their flavors, and also allows for better extraction.

It is important to remember that even the best filter can make a bad cup of coffee. The quality of the beans as well as the extraction, are still very important.

It's in this area that the magic takes place. This is what makes espresso taste so delicious. The grouphead, also referred to as the brew head, is where the portafilter (the thing you put the coffee ground into) is placed when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam, which then pushes the hot water through the grounds at a high pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. They are however limited in their ability for creating the ideal conditions for brewing 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 become more popular. They utilize an air compressor to push hot water through the ground and are much more mobile than electric steam-driven mini espresso machine machines.