How Does Machine Espresso Work?

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

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

The Group Head

The group head is the portafilter that you insert when brewing espresso. It disperses the water into the portafilter, and controls the pressure of the extraction. There are many different kinds of group heads, each with their own advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion capabilities, and still others are designed to control the lever. Some are a combination, like the E61. This is a popular choice among baristas as it provides a variety of advantages in one package.

As you can see in the above photo the head of the group is fitted with several notches. You place your portafilter in these notches and then twist the head to secure it. A gasket made of rubber is placed in the notches to create a seal when you insert your portafilter. The notches on the head allow for a precise location of the portafilter which is necessary for an even extraction.

The group head not only allows you to put in your portafilter easily, but it also maintains the same temperature. It does this by cycling hot water through the brew pan and around the portafilter, making sure that it is always at the correct temperature to extract. It is important to note that even a slight variation can mean the difference between a good and excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure that are required for espresso extraction. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven models, and they tend to last longer, although both types of machines can be damaged by excessive use and inadequate cleaning. They also create mechanical complexity, which can result in costly prices for even the most basic models.

Some espresso machines do away with the pump completely and make use of steam pressure to make espresso. The drawback of this is that the boiler that produces steam also increases the temperature of the water until it reaches boiling and can result in over-extraction. They also have to constantly rebuild their pressure between cups. This requires energy and time.

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

The Boiler

The boiler is the part that heats water to the optimal temperature for extraction. The steam that is created gets to the portafilter which is a container for espresso grounds. The steam is then channeled into the cup. The steam creates enough pressure to push the grounds of coffee through. This results in a layer of crema that is then poured over. This is the hallmark of a great espresso.

There are three types of espresso makers, which differ in the type of pump they use and how hot the coffee is. There are various ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-types. The first espresso machines were steam types. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semi-automatic machine that has an electric espresso maker pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the water flow and Machine Espresso pressure. This is an excellent solution that combines human control with mechanised accuracy.

The Filter

Espresso machines typically have a filter that separates the coffee grounds from the hot water. The filter is also a vital component of the machine's temp control, as it prevents overheating.

It also improves flavor as a filter allows for a more prolonged bloom phase. This helps the beans to release their nuances and gives an opportunity to improve extraction.

It is important to keep in mind that even the best filter can make a bad 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 brewhead, is where the portafilter (the container you place the ground coffee in) is placed when you're making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight container to create steam. The steam then pushes hot water into the grounds of the coffee under pressure. These types of machines are typically less expensive and simpler to maintain than pumps-driven models. However, they are limited in their ability to create the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.

In recent years, espresso maker for home machines powered by compressed air-pump are becoming increasingly popular. They utilize an air compressor to push hot water across the ground and are much more mobile than electric steam-driven espresso machines.