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How Does Machine Espresso Work?

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

To make an espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference.

The Group Head

As the name implies the group head is the place you place your portafilter while brewing espresso. It disperses the water into the portafilter and controls the pressure of the extraction. There are many different types of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. There are even some that have a combination of features, such as the E61, which is to be the most popular among baristas because of its ability to offer multiple perks in a single package.

As you can see from the picture above the group head has a number of notches. You place your portafilter into these notches and turn the head around to secure it. There is also a gasket made of rubber in the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches permit precise placement of your portafilter. This is crucial for an efficient extraction.

The group head not only lets the portafilter to be inserted easily however, it also keeps the same temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is always at the right level to extract the coffee. It is important to remember that even a few degree variation can mean 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 that pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure required to extract espresso. The pressure is created by drawing tap water from a reservoir, and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven models, and they tend to last longer. However, both types of machines could be damaged by excessive use and inadequate cleaning. They also increase the complexity of mechanical systems which can result in a high price tag on even the simplest models.

Some espresso machines use steam pressure instead of a pump in order to brew espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of water until it reaches boiling and can result in excessive extraction. The machines must also continually rebuild their pressure between cups. This takes energy and time.

Many espresso machines for home machines employ a vibration or rotary pump, with a vibrating model that uses a vibrating disc to create the pressure and the rotary model pushing hot water through the grounds under high speed. Both models can produce an excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component which heats the water to the optimal temperature to extract. The steam that is produced is then directed to the portafilter, which is a container for espresso grounds. The steam is then channeled into the cup. The steam is able to create enough pressure to push the grounds of the coffee through. This creates a foam on top of the espresso. This is a sign of a good espresso.

There are three different types of espresso machines, each having a different type of pump and the temperature of the brew. There are a variety of ways to control the brew and the size of cup that can be produced by the machine.

The first espresso machines were steam-type. The earliest espresso machines were steam types. This led to the coffee tasting bitter and burnt. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most popular professional espresso machine machine is a semiautomatic that has an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp your beans yourself The pump, however, regulates the water flow and pressure. This is an excellent compromise between human touch and mechanized consistency.

The Filter

Espresso machines usually use a filter that separates the coffee grounds from the hot water. The filter is also a vital component of the machine's temperature control, as it helps prevent overheating.

A filter also helps with flavor as it allows for a longer flowering period. This allows the beans to let their nuances out and provides an opportunity to improve extraction.

It is important to remember that even the best espresso machine uk filter can make a bad cup of coffee. The quality of the beans and the extraction process, remain vital.

This is where the magic happens, it's what makes espresso taste good. The grouphead, often called the brew head, is where the portafilter (the container you place the ground coffee in) is placed when making espresso.

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

In recent years, espresso machines driven by a compressed air pump have become increasingly popular. They utilize an air compressor to force hot water through the grounds and are much more portable than electric steam-driven machines.