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How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and mind-blowing filter technology to create the coffee we love. How does it work exactly?

To make an mini espresso machine hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.

The Head of the Group

The group head is the portafilter that is inserted when you are making espresso. It distributes water into the portafilter, and regulates the pressure of the extraction. There are several different types of group heads each with its unique advantages and drawbacks. Some are designed for stability of temperature while others are designed to handle pre-infusion. Others are built to control the lever. There are even some that contain a variety of features, like the E61 one, which is the most popular choice among baristas due to its ability to offer multiple benefits in a single package.

As you can see in the image above The group head features many notches in which you can place your portafilter and twist it manually to lock it in. There is also a gasket made of rubber that resides inside the notches and helps to create a seal when you insert your portafilter into the machine. The notches on the head permit a precise placement of the portafilter, which is vital to ensure an even extraction.

The group head does not just allow the portafilter to be inserted easily but also maintains the same temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, ensuring the temperature is always right for extraction. It is crucial to keep in mind that even a tiny differences can make the distinction between a decent and a excellent espresso.

The Pump

The motorized pumps used in espresso machines that rotate provide the nine atmospheric bars of pressure required for espresso extraction. This differs from manually operated piston machines that employ levers. The pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger prior being pumped through the ground coffee inside the group head.

Pumps are generally less expensive and last longer than piston-driven machines. However, both types of machines may degrade due to excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which can increase the cost of even simplest models.

Certain commercial espresso machine machines do away with the pump completely and use steam pressure to brew espresso. The downside is that the boiler that produces steam also increases the temperature of the water to boiling which can cause 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, which has a vibration model that uses a vibrating disc that generates the pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines can make excellent espresso but rotary machines are quieter, more durable and less likely to fail.

The Boiler

The boiler is what will heat the water to a temperature that is ideal for extraction. The steam that is produced is then directed to the portafilter, which holds the espresso grounds. It is then funneled into the cup. The steam generates enough pressure to push the grounds of the coffee through. This results in a layer of crema that is then poured over. This is one of the hallmarks of a good espresso.

There are three types of espresso makers, which differ in the type of pump they use and how hot the espresso is. There are various ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-types. They had a single boiler to make both steam and brew but the pressure they could create was minimal - two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. This is why the Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso machine is a semiautomatic model with an electric pump. This is what people envision when they think of an espresso machine. If you have a semi-automatic machine you grind the beans and tamp them by hand, but the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanized consistency.

The Filter

Espresso machines typically have filters that separate the grounds of the coffee from hot water. The filter is also a vital element of the machine's temperature control, as it prevents overheating.

It also improves flavor as a filter allows for a longer bloom time. This helps the beans let their nuances out and provides the chance for better extraction.

It is important to remember that even the finest filter can produce a bad cup of coffee. The quality of the beans, and the extraction process, are still very important.

It's here that the magic takes place. This is what makes espresso taste so good. The grouphead, often called the brewhead, is where the portafilter (the thing you put the ground coffee in) is placed when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds at high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

In recent years, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to push hot water across the ground and are much more mobile than electric steam-driven small espresso machine machines.