How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the coffee we love. But 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 however the main difference lies in the pressure.

The Group Head

As the name implies, the group head is where you insert your portafilter when making espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure that results from the extraction. There are various kinds of group heads each with its particular advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. There are also some that include a mix of features, such as the E61, which is the classic choice among many baristas due to its capacity to provide multiple benefits in one package.

As you can see in the picture above, the group head is fitted with a variety of notches. The portafilter is placed inside these notches, and then twist the head to lock it. There is also a gasket made of rubber which is located inside the notches and helps create a seal when you insert your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is essential for a consistent extraction.

Apart from allowing you easily insert your portafilter, the group head is responsible to maintain an even temperature. It does this by circulating hot water through the brew basket, and around the portafilter, ensuring that it's always at the correct temperature to extract. This is vital, because even a few degrees can make the difference between good and great espresso.

The Pump

In contrast to piston machines that are manually operated, which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure required for espresso extraction. This pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.

Pumps are typically less expensive than piston-driven machines, and tend to last longer, although both types of machines may be damaged by excessive use and inadequate cleaning. They also increase the complexity of mechanical systems, which can result in the cost of even the simplest models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso. The disadvantage of this is that the boiler that produces steam also increases the temperature of the water until it reaches boiling, which can lead to excessive extraction. They also have to continuously rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize a vibration or rotary pump, with a vibrating model using a rotating disc to generate the pressure, and rotating models that push hot water through the grounds under high speed. Both machines can produce excellent espresso but rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is used to heat the water to a temperature that is ideal to extract. The resulting steam is then transferred to the portafilter containing ground espresso beans and is then funneled down into the cup. During this process, the steam causes pressure to push through the grounds of the coffee. This results in a layer crema that is then poured over. This is one of the main characteristics of a great espresso.

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

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

The most commonly used espresso machine is a semiautomatic that has an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic espresso machine, you grind the beans and tamp them by hand. The pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanized accuracy.

The Filter

Typically, espresso machines utilize filters that 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, since it helps to prevent overheating.

Filters also aid in flavor, as it permits a longer flowering period. This helps the beans to release their flavors and provides an opportunity to improve extraction.

However, it is important to remember that even a high-quality filter could result in a bad cup of coffee as the quality of the beans and extraction are vital.

This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead (also known as the brewhead) is where you put the portafilter - the thingy which you put the grounds of your coffee into when making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam. Steam is then pushed through the grounds with high pressure. best budget espresso machine These machines are less expensive and are easier for the user to maintain than pumps-driven models. They are however limited for creating 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, compressed air pump-driven espresso machines have become more popular. They utilize an air compressor to push hot water across the ground, and are more mobile than electric steam-driven espresso machines.