The Comprehensive Guide To Machine Espresso

The Comprehensive Guide To Machine Espresso

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How Does Machine Espresso Work?

Machine espresso uses precision pressure and incredible filter technology to produce the delicious coffee we enjoy. What exactly does it work?

Espresso is created by forcing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee but the difference is in the pressure.

The Group Head

The group head is the portafilter is inserted when you are making espresso. It disperses water in the portafilter, and regulates the pressure of extraction. There are various kinds of group head, each with their particular advantages and drawbacks. Some focus on temperature stability, some on pre-infusion options, and others are designed to control the lever. Some come with a combination of both, such as the E61. This is a preferred choice for baristas because it offers multiple benefits in a single package.

As you can see in the image above, the group head has many notches in which you can place your portafilter and twist it by hand to lock it in. There is also a gasket of rubber that resides inside the notches and helps to create the seal when you insert your portafilter into the machine. The notches on the head permit an exact positioning of the portafilter which is necessary to ensure an efficient extraction.

The group head not only lets the portafilter to be inserted easily, but it also maintains the same temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure the temperature is always right to extract the coffee. It is important to remember that even a small difference can make the difference between a good and a great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure that are required for espresso extraction. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven machines and tend to last longer, but both types of machines could get damaged through overuse and lack of cleaning. They also add mechanical complexity which can result in an expensive price for even the simplest models.

Some espresso machines use steam pressure instead of a pump for brewing espresso. The drawback of this is that the boiler that produces steam also increases the temperature of water to boiling and can result in excessive extraction. They also have to constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines employ an rotary or vibrating pump, which is a vibration model that uses a vibrating disc to create the pressure, and rotating models that push hot water through the grounds at high speed. Both machines produce great espresso but rotary machines are more stable, quieter and less likely to break.

The Boiler

The boiler is the part which heats the water to the optimal temperature for extraction. The resulting steam reaches the portafilter which holds the ground espresso coffee, and is then pumped into the cup. The steam causes enough pressure to push the grounds of coffee through. This creates a crema on top of the espresso. This is one of the hallmarks of a good espresso.

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

The first espresso machines were steam types. They utilized only one boiler to make steam and brew, however, the pressure they could create was minimal - two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they picture these machines. If you have a semi-automatic machine you have to grind the beans and then tamp them by hand. However, the pump controls 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 to separate the grounds of the coffee as they go through the hot water. The filter is also a vital part of the machine's temperature control, as it helps prevent overheating.

Filters also aid in flavor as it allows for an extended flowering time. This helps the beans to let their nuances out and provides an opportunity for better extraction.

However, it is important to keep in mind that even a high-quality filter can produce a bad cup of coffee, since the quality of the beans and extraction are vital.

It's here that the magic happens. This is the reason machine espresso why espresso tastes so delicious. The grouphead, also referred to as the brew head, is where the portafilter (the device you put the coffee ground into) is located when you're making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water into the grounds of coffee at high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect 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 the ground and are much more mobile than steam-driven electric espresso machines.