How Does Machine Espresso Work?

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

Espresso is made by forcing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.

The Head of the Group

As the name suggests, the group head is where you insert your portafilter when brewing espresso. It disperses the water into the portafilter and regulates the pressure of the extraction. There are various kinds of group head, each with their particular advantages and drawbacks. Some focus on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. There are some that come with a range of features, such as the E61 that is the classic choice among many baristas due to its ability to offer multiple perks in a single package.

As you can see in the photo above, the group head has numerous notches that you can place your portafilter and then twist it with your hands to lock it in. A rubber gasket is located inside the notches to help create a seal when you insert your portafilter. The notches on the head permit an exact positioning of the portafilter which is vital for an efficient extraction.

Aside from allowing you to effortlessly insert your portafilter the group head is responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket, ensuring the temperature is always right for extraction. It is crucial to keep in mind that even a small deviation can make the difference between a great and a great espresso.

The Pump

The motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure that is required for espresso extraction. This is different from manual piston machines which use levers. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.

Pumps tend to be more affordable and last longer than piston-driven machines. However, both types of machines can degrade because of frequent use and insufficient cleaning. They also create mechanical complexity that can lead to the cost of even the simplest models.

Some espresso machines eliminate the pump completely and instead make use of steam pressure to make espresso. The drawback of this is that the boiler that produces steam also increases the temperature of water to the point of boiling and can result in excessive extraction. They also have to constantly rebuild their pressure in between cups. This requires energy and time.

Many espresso machines utilize an rotary or vibrating pump, with a vibrating model using a rotating disc that generates the pressure and an rotary model that pushes hot water through the grounds under high speed. Both models are capable of producing excellent barista espresso coffee machine, but the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is what will heat the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter that contains the ground espresso coffee and is then pumped into the cup. During this process the steam is able to create enough pressure to push the grounds of coffee through. This produces a layer of crema on top espresso machines. This is one of the main characteristics of a good 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 a variety of 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. They utilized 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 maximum. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

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

The Filter

espresso machine small machines typically use filters that separate the grounds of the coffee from the hot water. The filter is also an important component of the temperature control system, since it helps prevent the machine from overheating.

It also aids in flavor as a filter lets you enjoy a longer bloom time. This lets the beans release their nuances, and allows for better extraction.

However, it is important to remember that even a good filter could result in a bad cup of coffee, since the quality of the beans and extraction is still crucial.

It's in this area that the magic takes place. This is the reason why pro espresso machine tastes so good. The grouphead, often referred to as the brewhead, is where the portafilter (the container you place the coffee grounds into) is placed when making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then pushes hot water through coffee grounds under high pressure. These machines are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal brewing conditions, because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.

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