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How Does Machine Espresso Work?

Machine espresso uses precision pressure and amazing filter technology to make the delicious coffee and espresso machine we enjoy. What exactly is it that makes it work?

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

The Group Head

As the name suggests, the group head is where you insert your portafilter when making espresso. It disperses water in the portafilter, and regulates the pressure during the extraction. There are many different types of group heads each with their own advantages and disadvantages. Some are designed to provide the stability of temperature while some are designed to handle pre-infusion. Others are built to control the lever. There are even some that contain a variety of features, like the E61 one, which is the most popular choice among baristas due to its capacity to offer multiple perks in a single package.

As you can see in the above image The group head features many notches in which you can put your portafilter, then twist it manually to secure it. There is also a rubber gasket in the notches to help create a seal when you insert your portafilter into the machine. The notches on the head permit an exact location of the portafilter which is crucial to ensure an efficient extraction.

Aside from allowing you to easily connect your portafilter, the group head is responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew pan and around the portafilter to ensure that it's always at the correct temperature to extract. This is crucial, since just a few degrees could be the difference between a excellent and great espresso.

The Pump

In contrast to manual piston machines which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps that provide the nine atmospheric bars of pressure needed to extract cheap espresso machine. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.

Pumps are generally less expensive and last longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and poor cleaning. They also make mechanically complex and can lead to a high price tag on even the most basic models.

Certain espresso machines remove the pump entirely and utilize steam pressure to make espresso. The drawback of this is that the boiler that produces steam also raises the temperature of water to boiling and can result in excessive extraction. Additionally these machines typically have to rebuild their pressure between cups, which takes time and energy.

A large majority of espresso machines employ either a vibration or rotary pump. A vibration model employs a vibrating disk to generate pressure, while the Rotary model pushes hot coffee through the ground at a fast speed. Both models are capable of producing excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the one that makes the water warm to the perfect temperature to extract. The resultant steam then reaches the portafilter that contains the ground espresso and gets funnelled down into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This results in a crema on the top of the espresso. This is one of the main characteristics of a good espresso.

There are three types of espresso makers. They differ in the type of pump they employ and how hot the brew is. There are a variety of ways in which the brew could be controlled as well as the dimensions of the cup the machine can produce.

The first espresso machines were steam-type. The earliest espresso machines were steam types. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic device with an electric pump. This is what people envision when they think of an espresso machine. With a semi-automatic machine you must grind the beans and then tamp them yourself but the pump is able to regulate the flow of water and pressure. This is an excellent combination of human control and mechanized reliability.

The Filter

Typically, espresso machines employ filters to separate the grounds of coffee when they pass through the hot water. The filter is also a crucial component of the temperature control system since it helps prevent the machine from overheating.

A filter can also help with flavor because it allows for the beans to flower for a longer period of time. This allows beans to release their nuances and gives an opportunity for better extraction.

It is important to keep in mind that even the best Espresso machine under 200 filter can produce a bad cup of coffee. The quality of the beans and the extraction process remain vital.

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 place the portafilter, the device used to place the coffee grounds into, when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight container to produce steam, which then pushes the hot water through the grounds at a high pressure. These kinds of machines are usually less expensive and simpler to maintain than pumps-driven models. They are however limited in their ability to create the ideal 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 driven by a compressed air pump have become increasingly popular. They use an air compressor to push hot water into the grounds, and are far more portable than electric steam-driven machines.