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How Does Machine Espresso Work?

The machine espresso makes use of precise pressure and filtering technology that is amazing to create the coffee you enjoy. How does it work exactly?

To make an Decent Espresso Machine 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 group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are a variety of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion options, and others are designed to control the lever. There are also some that have a combination of features, like the E61 that is the standard choice for many baristas due to its capacity to provide multiple benefits in a single package.

As you can see in the photo above the head of the group is fitted with several notches. You place your portafilter in these notches and then twist the head to secure it. There is also a rubber gasket in the notches and helps to create a seal when you insert your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is vital for an accurate extraction.

The group head does not just allow you to place your portafilter easily however, it also keeps the temperature at a constant level. This is done by cycling hot water around the portafilter and through the brew-basket, making sure the temperature is always right for extraction. This is vital, because even a small difference in temperature can mean the difference between good and excellent espresso.

The Pump

Contrary to manual piston machines which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure needed for espresso extraction. This pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior being shot through the ground coffee inside the group head.

Pumps are typically less expensive than piston-driven machines, and tend to last longer, although both types of machines may degrade with overuse and insufficient cleaning. They also increase the complexity of mechanical systems which can result in the cost of even the simplest models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. The downside is that the boiler that produces steam also increases the temperature of water to the point of boiling, which can lead to excessive extraction. The machines must also constantly rebuild their pressure between cups. This requires energy and time.

Many espresso machines use a rotary or vibration pump. A vibration model makes use of a vibrating disk to generate pressure, whereas a circular model pushes hot liquid through the ground at a fast speed. Both machines can make great espresso however rotary machines tend to be more stable, quieter and less likely to fail.

The Boiler

The boiler heats the water to a temperature that is ideal for extraction. The steam produced reaches the portafilter, which is the container that holds the espresso coffee grounds. It is then funneled into the cup. The steam is able to create enough pressure to push the coffee grounds through. This creates a foam on the top of the espresso. This is a hallmark of a good espresso.

There are three kinds of espresso makers. They differ in the type of pump they employ and how hot the coffee is. There are a variety of ways in which the brew can be controlled, as well as the size of the cup the maker can create.

The first espresso machines were steam types. The earliest espresso machines were steam-type machines. The coffee espresso machine tasted bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern professional espresso machine for home machine.

The most well-known espresso maker is a semiautomatic machine with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the flow of water and pressure. This is an excellent combination of human control and mechanised accuracy.

The Filter

Espresso machines usually use filters that separate the grounds of the coffee from hot water. The filter is also an important part of the temperature control system as it keeps the machine from overheating.

A filter also improves flavor, as it permits the beans to flower for a longer period of time. This allows the beans to let their nuances out and provides an opportunity for a 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 the reason why espresso tastes so good. The grouphead (also called the brewhead) is where you place the portafilter, the device that you use to put the grounds of your coffee into when making espresso.

Steam-driven retro espresso machine machines make use of hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water into the coffee grounds under high pressure. These types of machines tend to be less expensive and simpler to maintain than pumps-driven models. They are however limited to create the perfect brewing conditions 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 been gaining popularity. They make use of an air compressor to push hot water across the ground. They are also more mobile than steam-driven electric espresso machines.