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How Does Machine Espresso Work?

The machine espresso is made using precise pressure, as well as a filtering technology that is amazing to create the coffee you love. What exactly is it that makes it work?

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

The Group Head

The name implies, the group head is where you insert your portafilter when making espresso. It disperses water into the portafilter, and controls the pressure of the extraction. There are a variety of types of group head each with its distinct advantages and drawbacks. Some focus on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some include a combination such as the E61. This is a preferred choice for baristas since it provides multiple benefits in one package.

As you can see in the image above the group head is fitted with a variety of notches. You place your portafilter in these notches and then turn the head around to secure it. There is also a gasket of rubber that resides inside the notches, which helps create a seal when you insert your portafilter into the machine. The notches permit the precise placement of the portafilter. This is vital for a consistent extraction.

Apart from allowing you easily insert your portafilter, the group head is responsible to ensure that the temperature remains even. It does this by circulating hot water through the brew pan and around the portafilter to ensure that it is always at the right temperature to extract. This is important, as even a few degrees can be the difference between a excellent and great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure necessary to extract espresso. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive than piston-driven models, and they tend to last longer, but both types of machines can degrade with overuse and insufficient cleaning. They also increase the complexity of mechanical systems, which can result in an expensive price for even the most basic models.

Some espresso machines for home machines can eliminate the pump completely and make use of steam pressure to make espresso. This can lead to over-extraction as the boiler that produces steam also causes the water to boil. The machines also need to constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines utilize an rotary or vibrating pump, with a vibrating model using a vibrating disc to generate the pressure, and the rotary model pushing hot water through the grounds under high speed. Both types of machine are capable of producing excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the part which heats the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter containing the ground espresso and is then pumped down into the cup. During this process, steam creates pressure that pushes through the coffee grounds. This results in a layer crema that is then poured over. This is the hallmark of a great espresso.

There are three distinct types of espresso machines, each having different types of pumps and the temperature of the brew. There are different ways to control the amount of brew, as well as the size of cup that can be made by the machine.

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

The most commonly used espresso machine is a semiautomatic one with an electric pump. These are what people imagine when they think of an espresso machine. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand. However, the pump provides regulated water flow and pressure. This is an excellent compromise between human touch and the mechanised consistency.

The Filter

Typically, espresso machines espresso machines employ filters to separate the grounds of the coffee as they go through the hot water. The filter is also a vital element of the machine's temperature control, as it helps prevent overheating.

It also enhances flavor as a filter lets you enjoy a longer bloom time. This lets the beans let their nuances out, and improves extraction.

It is important to remember that even the finest filter can make a bad cup of coffee. The quality of the beans, and the extraction process, are still very important.

It's here that the magic takes place. This is the reason why espresso tastes so delicious. The grouphead (also known as the brewhead) is where you put 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 tank to create steam. This then pushes the hot water through the grounds under high pressure. These kinds of machines are usually less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the perfect conditions for brewing, since they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9 bar espresso machine-10 bars.

In recent years, compressed air pump-driven espresso machines have become more popular. They use an air compressor to force hot water into the ground and are much more mobile than electric steam-driven espresso machines.