9 Things Your Parents Taught You About Machine Espresso

How Does Machine Espresso Work?

Machine espresso uses precision pressure and amazing filter technology to make the perfect cup of coffee. How exactly does it work?

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

The Group Head

The group head is the portafilter that is inserted when you are making espresso. It disperses water into the portafilter and regulates the pressure of the extraction. There are a variety of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, some on pre-infusion options, and others are designed to control the lever. There are some that contain a variety of features, such as the E61, which is considered to be the most popular among baristas for its ability to offer multiple benefits in one package.

As you can see from the picture above the head of the group is fitted with a variety of notches. It is possible to place your portafilter into these notches and turn the head around to secure it. A gasket of rubber is situated inside the notches, which helps create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is crucial for a consistent extraction.

The group head is not just able to allow you to insert your portafilter easily however it also keeps an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is at the right level to extract the coffee. It is crucial to keep in mind that even a few degree deviation can make the difference between a good and a excellent espresso.

The Pump

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

Pumps are generally cheaper and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of excessive use and poor cleaning. They also increase the complexity of mechanical systems and can lead to an expensive price for even the simplest models.

Some espresso machines employ steam pressure instead of a pump to make espresso. This can cause over-extraction because the boiler that produces steam also heats the water until it comes to a boil. The machines must also constantly rebuild their pressure between cups. This requires energy and time.

Many espresso machines use an rotary or a vibration pump. A vibration model employs a vibrating disk to generate pressure, while a rotary model pushes hot water through the ground at a high speed. Both models can make a great espresso coffee machine with milk frother, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats the water to the ideal temperature to extract. The steam that is produced reaches the portafilter which holds the ground espresso coffee and is then pumped into the cup. During this process, the steam creates 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 hallmarks of a great espresso.

There are three types of espresso makers. They differ in the kind of pump they use and the degree of heat that the coffee is. There are various ways to control the strength of the brew and the size of cup that can be produced by the machine.

The first espresso machines were steam-type. They utilized only one boiler to make both steam and brew however the pressure they were able to generate was low - only two bars of atmospheric pressure, at most. This led to the coffee tasting bitter and burnt. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker for home machine is a semiautomatic one with an electric pump. When people think of espresso machines, they envision these machines. If you have a semi-automatic machine you need to grind the beans and then tamp them yourself but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized quality.

The Filter

Typically, espresso coffee maker machines employ a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also an essential element of the temperature control system since it helps prevent the machine from overheating.

It also aids in flavor, as it lets you enjoy a longer bloom time. This allows beans to let their nuances out and provides an opportunity for better extraction.

It is important to remember that even the best espresso maker 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 espresso taste great. The grouphead (also called the brewhead) is where you put the portafilter, the thingy that you use to put the coffee grounds in, when making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to make steam. The steam then pushes hot water into the grounds of the coffee under pressure. They are less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect 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 utilize an air compressor to force hot water through the grounds, and are far more portable than steam-driven electric machines.