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How Does Machine Italian Espresso Machines Work?

Machine espresso employs precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. But how exactly does it work?

Espresso is created by forcing hot water 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 group head is the portafilter that you put in when making espresso. It disperses the water into the portafilter and controls the pressure of the extraction. There are many different kinds of group head, each with their unique advantages and drawbacks. Some are designed for stability of temperature while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some include a combination like the E61. This is a very popular choice for baristas as it provides a variety of advantages in a single package.

As you can see in the image above the group head is made up of many notches in which you can place your portafilter and then twist it with your hands to lock it in. A gasket made of rubber is placed inside the notches, which helps create a seal while you insert your portafilter. The notches permit precise placement of the portafilter. This is essential for a consistent extraction.

The group head not only lets you to place your portafilter easily however it also keeps a constant temperature. This is done by cycling hot water around the portafilter and through the brew-basket to ensure the temperature is always right for extraction. This is important because even a few degrees can make the difference between good and excellent espresso.

The Pump

The motorized pumps in espresso machines that rotate provide the nine atmospheric bars of pressure required for espresso extraction. This is different from manual piston machines which use levers. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading due to overuse and insufficient cleaning. They also increase the complexity of mechanical systems which can result in an expensive price for even the most basic models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. The drawback is that the same boiler that produces steam also raises the temperature of water to the point of boiling which could lead to excessive extraction. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time.

Many espresso machines employ an rotary or vibrating pump, which has a vibration model using a vibrating disc to create pressure, and the rotary model pushing hot water through the grounds at high speed. Both machines can make excellent best home espresso machine however rotary machines tend to be more stable, quieter and less likely to break down.

The Boiler

The boiler is what heats the water to the perfect temperature for extraction. The steam produced is then directed to the portafilter, which contains the espresso coffee grounds. It is then funneled into the cup. The steam generates enough pressure to push the grounds of coffee through. This results in a layer crema on top espresso machines. This is a hallmark of a good espresso.

There are three distinct types of espresso machines, each with distinct pumps and brew temperature. There are different ways to control the strength of the brew and the size of cup that can be made by the machine.

The earliest espresso makers machines were steam-based. They used only one boiler to make both steam and brew however the pressure they were able to create was minimal - two bars of atmospheric pressure, at most. The coffee tasted bitter and burnt. This is the reason Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used espresso maker is a semi-automatic machine that has an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans by yourself while the pump controls the flow of water and pressure. This is a fantastic compromise between human control and mechanised accuracy.

The Filter

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

Filters also aid in flavor because it allows for an extended flowering time. This helps the beans release their flavors and provides the chance for better extraction.

However, it is important to remember that even a great filter can result in a poor cup of coffee as the quality of the beans and extraction are essential.

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

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at a high pressure. These types of machines are usually cheaper and easier to maintain than pump-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, since they are only operating at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water into the grounds and are significantly more portable than steam-driven electric machines.