How Does Machine Espresso Work?

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

Espresso is made by forcing hot water under 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 you put in when making espresso. It disperses the water into the portafilter and regulates the pressure of extraction. There are many different kinds of group head each with its particular advantages and drawbacks. Some are designed for the stability of temperature while some are built to handle pre-infusion. Others are built to control the lever. Some have a combination, such as the E61. This is a very popular choice for baristas since it provides multiple benefits in a single package.

As you can see from the image above the group head is equipped with several notches. It is possible to place your portafilter inside these notches, and then twist the head to secure it. There is also a gasket made from rubber that is a part of the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for a precise position of the portafilter which is vital for an even extraction.

The group head not only lets you to place your portafilter easily, but it also maintains the same temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is at the right level to extract the coffee. It is important to realize that even a small differences can make the distinction between a decent and a great cafe Espresso machine.

The Pump

In contrast to piston machines that are manually operated, that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure needed to extract espresso. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading due to excessive use and inadequate cleaning. They also add mechanical complexity which can result in a high price tag on even the most basic models.

Some espresso machines use steam pressure instead of a pump for brewing espresso. This can result in over-extraction because the boiler that makes steam also warms the water to boil. The machines must also continuously rebuild their pressure between cups. This requires energy and time.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, whereas a Rotary model pushes hot coffee through the ground at a fast speed. Both machines can make excellent espresso, but rotary machines are quieter, more durable and less likely to fail.

The Boiler

The boiler heats the water to a temperature that is ideal to extract. The steam created gets to the portafilter which holds the espresso grounds. It is then poured into the cup. The steam creates pressure that pushes through the grounds of the coffee. This results in a whipped-up top of the espresso. This is one of the main characteristics of a good espresso.

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

The earliest espresso machines were steam types. The first espresso machines were steam-type machines. The coffee tasted bitter and burned. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized quality espresso machine.

The Filter

Typically, espresso machines have filters that separate the grounds of coffee as they move through the hot water. The filter is also a vital element of the machine's temperature control, since it helps to prevent overheating.

It also helps with flavor, since a filter allows for a more prolonged bloom phase. This helps the beans to release their flavors and provides the chance for better extraction.

It is important to keep in mind that even the most efficient filter could result in a poor cup of coffee. The quality of the beans and the extraction process remain crucial.

This is where the magic happens, and it's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you place the portafilter, which is the thingy that you use to put the coffee grounds in, when making espresso.

In a steam-driven espresso machine hot water is heated in an airtight container to create steam. Steam then pushes the hot water through the grounds at a high pressure. These types of machines are usually less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing, as they 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 utilize an air compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.