How Does Machine Espresso Work?

The machine espresso makes use of precision pressure, and filter technology that is mind-blowing to create the coffee you love. How exactly does it work?

Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.

The Head of the Group

As the name implies the group head is the place you insert your portafilter when making espresso. It disperses water in the portafilter, and controls the pressure of the extraction. There are various kinds of group head, each with their distinct advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. Some include a combination such as the E61. This is a popular choice among baristas because it offers multiple advantages in one package.

As you can see in the picture above the head of the group is fitted with a variety of notches. You place your portafilter in these notches, then twist the head to secure it. There is also a gasket made from rubber which is located inside the notches, which helps 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 a consistent extraction.

In addition to allowing you to easily connect your portafilter, the group head is responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it's always at the correct temperature to extract. It is crucial to keep in mind that even a few degree variation can mean the difference between a good and a excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure necessary to extract espresso. This pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger prior to it is shot through the ground coffee in the group head.

Pumps are typically less expensive and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to excessive use and inadequate cleaning. Pumps are also more complicated mechanically, which can raise the cost of even the simplest models.

Some espresso machines use steam pressure instead of a pump in order to brew discount espresso machines. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. The machines must also constantly rebuild their pressure between cups. This requires energy and time.

A large majority of espresso machines employ an rotary or a vibration pump. A vibration model employs a vibrating disk to generate pressure, whereas the Rotary model pushes hot coffee through the ground at a high speed. Both machines can produce excellent espresso coffee machine for home but rotary machines are more stable, quieter and less likely to break.

The Boiler

The boiler will heat the water to the right temperature for extraction. The resulting steam reaches the portafilter which holds the ground espresso and is then pumped down into the cup. The steam causes pressure to push through the coffee grounds. This results in a layer crema that is then poured over. This is a hallmark of a great espresso maker barista.

There are three kinds of espresso makers, which differ in the type of pump they use and the degree of heat that the coffee is. There are various ways in which the brew can be controlled, as well as the size of the cup the machine can make.

The earliest espresso machines were steam-based. They utilized only one boiler to make both brew and steam, but the pressure they could produce was very low - just two bars of atmospheric pressure at most. The coffee tasted bitter and burned. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic machine, you have to grind the beans and tamp them by hand. The pump regulates the flow of water and pressure. This is an excellent compromise between human control and mechanised reliability.

The Filter

Espresso machines espresso usually have a filter that separates the grounds of the coffee from the hot water. The filter is also an essential component of the machine's temperature control, since it stops overheating.

A filter also helps with flavor, as it permits a longer flowering period. This allows the beans to let their nuances out, and also allows for better extraction.

It is important to remember that even the most efficient filter can result in a bad cup of coffee. The quality of the beans as well as the extraction, are still crucial.

It's here that the magic takes place. This is what makes espresso taste so good. The grouphead, sometimes referred to as the brew head, is where the portafilter (the thingy you put the coffee grounds into) is placed when you're making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight container to create steam. The steam then pushes hot water through grounds of coffee under high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal brewing conditions, since they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

In recent years, espresso machines powered by a compressed air compressor have become increasingly popular. They utilize an air compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.