How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and incredible filter technology to produce the coffee we love. How exactly does it work?

To make an espresso, hot water is forced under high end espresso machine pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.

The Head of the Group

The group head is the portafilter that you insert when brewing espresso. It distributes water into the portafilter and regulates the pressure of the extraction. There are several different types of group head each with its unique advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. There are also some that come with a range of features, such as the E61, which is considered the classic choice among many baristas due to its capacity to offer multiple benefits in a single package.

As you can see from the above photo the group head is equipped with several notches. The portafilter is placed inside these notches, and then turn the head around to secure it. There is also a gasket made of rubber which is located 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 location of the portafilter which is vital for a consistent extraction.

Apart from allowing you easily connect your portafilter, the group head is responsible to ensure that the temperature remains even. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is at the right level for extraction. It is important to realize that even a few degree differences can make the distinction between a great and a great espresso.

The Pump

The motorized pumps that are used in rotary espresso machines provide the nine atmospheric bar pressure that is required for espresso extraction. This is different from manually operated piston machines that employ levers. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be more affordable and last longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and inadequate cleaning. They also increase the complexity of mechanical systems, which can result in a high price tag on even the simplest models.

Some best cheap espresso machine machines remove the pump completely and make use of steam pressure to make espresso. The drawback is that the same boiler that produces steam also increases the temperature of water to the point of boiling, which can lead to over-extraction. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines employ a vibration or rotary pump, with a vibrating model that uses a vibrating disc that generates the pressure and the rotary model pushing hot water through the grounds at high speed. Both machines can make excellent espresso, but rotary machines are more stable, quieter and less likely to break down.

The Boiler

The boiler heats the water to a temperature that is ideal for extraction. The steam that is created is then directed to the portafilter, which is a container for espresso grounds. It is then funneled into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This produces a layer of crema that is then poured over. This is one of the hallmarks of a good espresso.

There are three types of espresso makers, and they differ in the type of pump they employ and how hot the espresso is. There are different ways that the brew can be controlled and the size of the cup the machine can produce.

The first espresso machines were steam types. They used only one boiler to make both steam and brew however, the pressure they could produce was not very high – two bars of atmospheric pressure, at most. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso machine is a semiautomatic that has an electric pump. These are the images people have when they think of an Espresso Machine Small machine. Semi-automatic machines require you to grind and tamp the beans by yourself however the pump controls the flow of water and pressure. This is a great compromise between human control and mechanised accuracy.

The Filter

Typically, espresso machines utilize a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also a vital part of the machine’s temperature control, as it helps prevent overheating.

A filter can also help with flavor as it allows for an extended flowering time. This lets the beans release their flavors, and 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 and the extraction process, remain vital.

It’s here that the magic occurs. This is what makes espresso taste so delicious. The grouphead, often referred to as the brew head, is where the portafilter (the container you place the ground coffee machines espresso in) sits when you’re making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight vessel to create steam. The steam then pushes hot water into the coffee grounds under high pressure. These types of machines are generally cheaper and easier to maintain than pumps-driven models. They are however limited in their ability to create the ideal conditions for brewing as 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 been gaining popularity. They use an air compressor to force the hot water through the grounds, and are far more portable than steam-driven electric machines.