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How Does Machine Espresso Work?

The machine espresso is made using precise pressure, as well as a filter technology that is mind-blowing to make the coffee you enjoy. What exactly is it?

Espresso is created by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee. However the pressure is the major difference.

The Group Head

As the name implies the group head is the place you put your portafilter in when brewing best espresso maker. It distributes water into the portafilter, and controls the pressure of the extraction. There are many different kinds of group heads each with its distinct advantages and disadvantages. Some are designed to provide the stability of temperature while some are designed to handle pre-infusion. Others are built to control the lever. Some have a combination, such as the E61. This is a preferred choice for baristas since it provides multiple benefits in one package.

As you can see in the image above the group head comes with several notches where you place your portafilter and twist it by hand to lock it in. There is also a gasket of rubber in the notches and helps to create the seal when you insert your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is crucial for an efficient extraction.

The group head not only allows the portafilter to be inserted easily, but it also maintains the temperature at a constant level. This is accomplished by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is always at the right level for extraction. This is important because just a few degrees could be the difference between a excellent and great espresso.

The Pump

Contrary to manual piston machines which rely on a lever to pressurize water, Rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure that are required for espresso maker barista extraction. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior being shot through the best ground coffee for espresso machine coffee inside the group head.

Pumps are typically cheaper and last longer than piston-driven machines. However, both types of machines can degrade due to excessive use and insufficient cleaning. They also make mechanically complex, which can result in the cost of even the simplest models.

Certain decent espresso machine 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 are often required to rebuild their pressure between cups, which takes time and energy.

Many espresso machines employ a vibration or rotary pump, with a vibration model using a rotating disc to create the pressure, and rotating models that push hot water through the grounds at high speed. Both machines can make excellent espresso, however rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is what heats the water to a temperature that is ideal for extraction. The resultant steam then reaches the portafilter containing ground espresso beans and gets funnelled down into the cup. During this process, steam creates pressure that pushes through the grounds of the coffee. This creates a foam on top of the espresso. This is one of the hallmarks of a good espresso.

There are three kinds of espresso makers, which differ in the type of pump they employ and how hot the brew is. There are various ways that the brew can be controlled as well as the dimensions of the cup the machine is capable of making.

The first espresso machines were steam-type. They used a single boiler to make both brew and steam, however the pressure they were able to create was minimal - two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso machine is a semiautomatic 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 then tamp them yourself but the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and the mechanised quality.

The Filter

Typically, espresso machines have filters that separate the grounds of coffee as they move through the hot water. The filter is also an essential part of the machine's temperature control, since it stops overheating.

It also enhances flavor, since a filter lets you enjoy a longer bloom time. This lets the beans release their nuances, and improves extraction.

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

This is where the magic happens, and it's what makes espresso taste great. The grouphead, sometimes called the brew head, is where the portafilter (the thingy you put the ground coffee in) is placed when you're 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 less expensive and easier to maintain than pump-driven models. They are however limited in their ability to create 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 compressor have become increasingly popular. They use an air compressor to force the hot water through the grounds, and are far more portable than electric steam-driven machines.