13 Things About Machine Espresso You May Not Have Known

How Does Machine Espresso Work?

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

In order to make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the major difference.

The Head of the Group

The group head is the portafilter you place in the espresso maker when making it. It distributes water into the portafilter and regulates 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, some on pre-infusion options, and others are designed to control the lever. Some are a combination, such as the E61. This is a preferred choice for baristas because it offers multiple advantages in one package.

As you can see in the image above the group head comes with numerous notches that you can place your portafilter before twisting it manually to secure it. There is also a gasket of rubber that is a part of the notches, which 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 to ensure an efficient extraction.

The group head does not just allow you to insert your portafilter easily, but it also maintains a constant temperature. It does this by circulating hot water through the brew basket and around the portafilter, making sure that it is always at the right temperature for extraction. This is crucial, since even a small difference in temperature can mean the difference between good and excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure that are required for espresso extraction. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger prior it is shot through the ground coffee inside the group head.

Pumps are generally less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade because of excessive use and poor cleaning. Pumps are also more complicated mechanically, which could increase the cost of even the most basic models.

Some espresso machines espresso machines do away with the pump completely and instead make use of steam pressure to make espresso. This can cause over-extraction because the boiler that makes steam also heats the water until it comes to a boil. These machines also have to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines use either a vibration or rotary pump. A vibration model employs the vibrating disk to create pressure, whereas a circular model pushes hot liquid through the ground at high speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to break down.

The Boiler

The boiler is the component which heats the water to the ideal temperature to extract. The resulting steam is then transferred to the portafilter containing the ground espresso coffee and is then pumped down into the cup. During this process, steam creates pressure to push through the coffee grounds. This creates a crema on top of the espresso. This is a sign of a great espresso.

There are three types of espresso makers. They differ in the type of pump they employ and the degree of heat that the brew is. There are different ways that the brew may be controlled as well as the size of the cup that the maker can create.

The earliest espresso machines were steam type. They employed one boiler to make both steam and brew however the pressure they were able to produce was not very high - two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso maker is a semi-automatic one that has an electric pump. These are what people imagine when they think of an espresso maker. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand. However, the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanised accuracy.

The Filter

Typically, espresso machines employ filters that separate the grounds of the coffee as they go through the hot water. The filter is also an essential element of the temperature control system, because it stops the machine from overheating.

It also improves flavor, as a filter can allow for a longer bloom time. This lets the beans let their nuances out, and improves extraction.

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

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

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam, which is then pushed through the grounds at high pressure. They are less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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