How Does Machine Espresso Work?

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

To make espresso, hot water is forced under 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 insert 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 particular advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion options, and others are designed to control the lever. Some have a combination, like the E61. This is a favorite among baristas due to the fact that it has multiple benefits in a single package.

As you can see in the photo above the group head is fitted with a variety of notches. You place your portafilter inside these notches, and then twist the head to lock it. There is also a gasket of rubber that resides inside the notches to help create an airtight seal after inserting your portafilter into the machine. The notches allow for an exact placement of the portafilter. This is crucial to ensure a consistent extraction.

In addition to allowing you effortlessly insert your portafilter the group head is also responsible to maintain an even temperature. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, ensuring the temperature is always right to extract the coffee. This is important because just a few degrees could be the difference between a excellent and great espresso.

The Pump

In contrast to piston machines that are manually operated, that use a lever to pressurize water, rotating espresso machines rely upon motorized pumps to deliver the nine atmospheric bars of pressure that are required to extract espresso. The pressure is built by pumping water through a heat exchanger and then through the best ground coffee for espresso machine coffee.

Pumps tend to be cheaper and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to excessive use and poor cleaning. Pumps are also more complex mechanically, which can raise the price of even the most basic models.

Some espresso machines do away with the pump completely and instead use steam pressure to brew espresso. The drawback of this is that the boiler that produces steam also raises the temperature of water to boiling, which can lead to over-extraction. The machines must also continuously rebuild their pressure between cups. This takes energy and time.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model employs a rotating disk to generate pressure, whereas a rotary model pushes hot water through the ground at a high speed. Both types of machines can make excellent espresso, however the rotary models 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 resultant steam then reaches the portafilter that contains the ground espresso and is then pumped into the cup. During this process the steam generates enough pressure to push the grounds of coffee through. This results in a layer crema on top. This is one of the hallmarks of a great espresso.

There are three types of espresso makers, which differ in the type of pump they employ and the degree of heat that the coffee is. There are many ways to control the brew as well as the size of cup that can be produced by the machine.

The first espresso machines were steam-types. The earliest espresso machines were steam types. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso maker is a semiautomatic machine with an electric pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and the mechanized quality.

The Filter

Espresso machines usually use filters that separate the grounds of coffee from hot water. The filter is also a vital component of the machine's temperature control, since it stops overheating.

It also enhances flavor, as it can allow for a longer bloom time. This allows the beans to release their nuances, and allows for better extraction.

It is important to remember that even the finest filter could result in a poor Retro Espresso Maker cup of coffee. The quality of the beans and the extraction, remain vital.

This is where the magic happens, it's the thing that makes an espresso really taste good. The grouphead (also known as the brewhead) is where you put the portafilter - the thingy used to place the grounds of coffee into when making espresso machines home.

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

In recent years, espresso machines home machines driven by compressed air-pump are becoming increasingly popular. They make use of an air compressor to force hot water into the ground. They are also more mobile than electric steam-driven espresso machines.