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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to make the coffee we love. What exactly does it work?

In order to make espresso hot water is forced under high 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 name implies the group head is where you put your portafilter in when brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure that results from the extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some are designed for the stability of temperature while some are specifically designed to handle pre-infusion. Others are made to control the lever. Some come with a combination of both, such as the E61. This is a favorite among baristas because it offers multiple benefits in a single package.

As you can see in the above photo, the group head is fitted with a variety of notches. You can place your portafilter in these notches, then twist the head to lock it. A gasket made of rubber is placed in the notches to create a seal as you insert your portafilter. The notches allow for the precise placement of the portafilter. This is vital for an accurate extraction.

The group head not only allows you to place your portafilter easily however, it also keeps an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket, making sure the temperature is always right for extraction. It is crucial to keep in mind that even a slight difference can make the difference between a decent espresso machine and a great espresso.

The Pump

Unlike manual piston machines, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure necessary for espresso machine with milk frother extraction. This pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven machines, and they tend to last longer, however both types of machines may become damaged due to excessive use and poor cleaning. Pumps are also more complex mechanically, which could increase the cost of even the simplest models.

Certain espresso machines remove the pump completely and instead employ steam pressure to create espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water until it reaches boiling which could lead to excessive extraction. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines make use of the rotary or vibration pump, with a vibration model using a rotating disc to create the pressure, and an rotary model that pushes hot water through the grounds at high speed. Both machines can make great espresso but rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is the component that heats the water to the optimal temperature for extraction. The steam that is created will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then funneled into the cup. During this process, steam creates pressure and 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 commercial espresso machine.

There are three kinds of best budget espresso machine makers, and they differ in the type of pump they employ and the degree of heat that the coffee is. There are various ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.

The first espresso machines were steam-type. The first espresso machines were steam types. This led to the coffee tasting burnt and bitter. This is the reason why Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most common espresso machine is a semiautomatic one with an electric pump. These are the images people have when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the water flow and pressure. This is an excellent compromise between human control and mechanised accuracy.

The Filter

Typically, espresso machines employ filters to separate the grounds of coffee as they move through the hot water. The filter is also an important part of the temperature control system, as it prevents the machine from overheating.

Filters also aid in flavor since it allows for a longer flowering phase. This allows beans to release their flavor and gives an opportunity for better extraction.

However, it is important to remember that even a great filter can produce a bad cup of coffee as the quality of the beans and extraction is still essential.

This is where the magic happens, it's what makes an espresso really taste good. The grouphead (also known as the brewhead) is where you put the portafilter, which is the thingy used to place the grounds of coffee into when making espresso.

In the steam-driven espresso machine hot water is heated in an airtight container to create steam, which then pushes the hot water through the grounds under high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. They are however limited 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, espresso machines powered by a compressed air pump have become increasingly popular. They use an air compressor to push hot water through grounds and are much more portable than steam-driven electric machines.