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How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the perfect cup of coffee. What exactly is it?

In order to make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the difference is in the pressure.

The Head of the Group

The group head is the portafilter that you put in when making espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are numerous kinds of group heads each with distinct advantages and disadvantages. Some are designed to provide stability of temperature while others are designed to handle pre-infusion. Some are designed to control the lever. Some have a combination of features, like the E61, which is considered the standard choice for many baristas because of its ability to provide multiple benefits in a single package.

As you can see in the above image the group head comes with many notches in which you can put your portafilter, then twist it by hand to secure it. There is also a gasket made of rubber which is located inside the notches to help create an airtight seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is crucial to ensure an even extraction.

Apart from allowing you easily connect your portafilter, the group head is also responsible for maintaining an even temperature. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it is always at the right temperature to extract. It is important to realize that even a best small espresso machine difference can make the difference between a good and a great espresso.

The Pump

The motorized pumps in rotary espresso machines supply the nine atmospheric bar pressure that is required for espresso extraction. This is different from manual piston machines which use a lever. The pressure is created by removing tap water from a reservoir and pumping it through a heat exchanger prior being pushed through the ground coffee inside the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade because of excessive use and poor cleaning. They also increase the complexity of mechanical systems and can lead to the cost of even the simplest models.

Some best espresso maker machines make use of steam pressure instead of a pump for brewing espresso. The downside is that the boiler that produces steam also raises the temperature of the water until it reaches boiling which can cause over-extraction. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model employs a rotating disk to generate pressure, while the rotating model pushes hot water through the ground at a rapid speed. Both machines can make excellent espresso, but rotary machines are quieter, more durable and less likely to break down.

The Boiler

The boiler is the part that heats water to an ideal temperature to extract. The steam created will eventually reach the portafilter, which is a container for espresso grounds. It is then poured into the cup. During this process, the steam causes pressure to push through the coffee grounds. This results in a crema on the top of the espresso. This is a hallmark of a great mini espresso maker.

There are three types of espresso machines, each having a different type of pump and the temperature of the brew. There are many ways to control the amount of brew, as well as the size of cup that can be produced by the machine.

The first Mini Espresso Maker machines were steam-type. They utilized only one boiler to make both steam and brew but the pressure they could generate was low - only two bars of atmospheric pressure maximum. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machines, they imagine 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 great compromise between the human touch and mechanized quality.

The Filter

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

It also enhances flavor, as a filter can allow for a longer bloom phase. This allows the beans to release their flavor and allows for better extraction.

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

This is where the magic happens, it's the thing that makes espresso taste good. The grouphead, sometimes referred to as the brew head, is where the portafilter (the thingy you put the coffee ground into) sits when you're making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight container to produce steam, which is then pushed through the grounds at high pressure. These kinds of machines are usually less expensive and simpler to maintain than pumps-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, because they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They use an air compressor to force hot water into the grounds and are more portable than steam-driven electric machines.