9 . What Your Parents Taught You About Machine Espresso

How Does Machine Espresso Work?

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

To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee but the difference is in the pressure.

The Group Head

The name implies the group head is where you place your portafilter when making espresso. It disperses water in the portafilter and regulates the pressure of extraction. There are many different kinds of group head, each with their unique advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. Some are a combination, such as the E61. This is a favorite among baristas as it provides a variety of benefits in one package.

As you can see from the photo above, the group head is equipped with several notches. You place your portafilter in these notches and then 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 precise placement of your portafilter. This is crucial for an even extraction.

The group head does not just allow you to insert your portafilter easily, but it also maintains an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket, making sure the temperature is always right to extract the coffee. It is important to note that even a few degree deviation can make the difference between a good and excellent commercial espresso machine.

The Pump

Unlike manual piston machines, which rely on a lever that pressurize water, rotary barista espresso coffee machine machines rely on motorized pumps to provide the nine atmospheric bars of pressure necessary to extract espresso. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee inside the group head.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of excessive use and insufficient cleaning. Pumps are also more complicated mechanically, and can add to the cost of even simplest models.

Some espresso machines use steam pressure instead of a pump for brewing espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of water to boiling and can result in over-extraction. The machines also need to constantly rebuild their pressure in between cups. This requires energy and time.

Many espresso machines employ an rotary or vibrating pump, which is a vibration model using a vibrating disc that generates the pressure and rotating models that push hot water through the grounds under high speed. Both types of machines are capable of producing excellent espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats the water to the optimal temperature to extract. The steam created reaches the portafilter, which is the container that holds the espresso coffee grounds. It is then poured into the cup. During this process, steam creates pressure to push through the coffee grounds. This creates a foam on top of the decent espresso machine. This is the hallmark of a great espresso.

There are three kinds of espresso makers. They differ in the kind of pump they use and the degree of heat that the espresso is. There are various ways to control the brew as well as the size of the cup that can be made by the machine.

The first espresso machines were steam-type. They utilized one boiler to create both brew and steam, however the pressure they were able to produce was not very high - two bars of atmospheric pressure at most. This resulted in the coffee tasting bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most common espresso machine is a semiautomatic that has an electric pump. These are the things people think of when they think of an espresso maker. If you have a semi-automatic machine you grind the beans and then tamp them yourself but the pump controls the flow of water and pressure. This is an excellent solution that combines human control with mechanised reliability.

The Filter

Typically, buy espresso machines machines use filters to separate the grounds of coffee as they move through the hot water. The filter is also an essential component of the machine's temp control, as it prevents overheating.

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

However it is crucial to keep in mind that even a great filter can result in a poor cup of coffee, since the quality of the beans and extraction is essential.

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 place the portafilter, the thingy that you use to put the coffee grounds into, when making espresso.

In a steam-driven espresso machine hot water is heated in an airtight container to create steam. Steam then pushes the hot water through the grounds at high pressure. These types of machines tend to be less expensive and easier to maintain than pumps-driven models. They are however limited in their ability for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent times, Espresso coffee machine home machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to force the hot water through the grounds, and are far more portable than electric steam-driven machines.