The 9 Things Your Parents Taught You About Machine Espresso

How Does Machine Espresso Work?

Machine espresso employs precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. But how exactly does it work?

Espresso is produced by pushing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the main difference.

The Head of the Group

As the name suggests, the group head is where you put your portafilter in when making espresso. It is responsible for dispersing water into the portafilter and controlling the pressure of the extraction. There are a variety of group heads each with its own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion features, and others are designed to control the lever. There are even some that include a mix of features, such as the E61, which is the most popular choice among baristas due to its ability to provide multiple benefits in one package.

As you can see in the above photo, the group head has numerous notches that you can place your portafilter before twisting it by hand to secure it. There is also a gasket of rubber which is located inside the notches and helps create the seal when you insert your portafilter into the machine. The notches on the head allow for an exact location of the portafilter which is vital for an even extraction.

Aside from allowing you to easily place your portafilter in, the group head is also responsible to ensure that the temperature remains even. It does this by circulating hot water through the brew basket and around the portafilter, ensuring that it is always at the right temperature to extract. It is important to note that even a few degree differences can make the distinction between a good and a excellent espresso.

The Pump

The motorized pumps that are used in mini espresso maker machines that rotate provide the nine atmospheric bar pressure that is required to extract espresso. This differs from manual piston machines that use a lever. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines may degrade due to excessive use and insufficient cleaning. Pumps are also more complicated mechanically, and can add to the price of even the simple models.

Some espresso machines make use of steam pressure instead of a pump to make espresso machines home. The drawback of this is that the boiler that produces steam also raises the temperature of the water to boiling which can cause over-extraction. In addition these machines are often required to restore their pressure between cups, which requires time and energy.

Many espresso machines make use of the rotary or vibration pump, with a vibrating model using a rotating disc to create pressure, and rotating models that push hot water through the grounds under high speed. Both machines can make great espresso however rotary machines tend to be quieter, more durable and less likely to break.

The Boiler

The boiler is the one that makes the water warm to the ideal temperature for extraction. The resultant steam then reaches the portafilter that contains the ground espresso coffee and is then pumped down into the cup. The steam causes pressure to push through the grounds of the coffee. This creates a foam on the top of the espresso. This is one of the main characteristics of a great espresso.

There are three types of espresso makers, and they differ in the type of pump they use and how hot the espresso is. There are a variety of ways in which the brew could be controlled as well as the size of the cup the machine can make.

The first espresso machines were steam type. They had a single boiler to make both steam and brew, however, the pressure they could generate was low - only two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker is a semi-automatic espresso machine device with an electric pump. These are the images people have when they think of an espresso maker. If you have a semi-automatic machine you have to grind the beans and tamp them yourself but the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanised accuracy.

The Filter

Espresso machines usually use filters that separate the coffee grounds from the hot water. The filter is also an essential element of the temperature control system because it stops the machine from overheating.

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

It is important to keep in mind that even the best filter could result in a poor cup of coffee. The quality of the beans as well as the extraction, remain vital.

This is where the magic happens, it's what makes espresso taste great. The grouphead, often referred to as the brew head, is where the portafilter (the thingy you put the coffee espresso machines ground into) is placed when making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at high pressure. These machines are cheaper and easier for the owner 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 ideal 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 into the grounds and are significantly more portable than electric steam-driven machines.