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How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and mind-blowing filter technology to make the perfect cup of coffee. What exactly is it?

To make an espresso and filter coffee machine hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the primary difference.

The Group Head

The name implies, the group head is the place you place your portafilter while making italian espresso machines. It is responsible for dispersing the water into the portafilter and controlling the pressure that results from the extraction. There are various kinds of group head, each with their particular advantages and drawbacks. Some are designed for stability in temperature, while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some have a combination, like the E61. This is a preferred choice for baristas since it provides multiple benefits in one package.

As you can see in the above image the group head is made up of several notches to place your portafilter and then twist it with your hands to secure it. There is also a gasket made from rubber that is a part of the notches and helps create a seal when you insert your portafilter into the machine. The notches on the head permit an exact position of the portafilter which is crucial to ensure an even extraction.

In addition to allowing you 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 that the temperature is at the right level for extraction. It is important to remember that even a few degree difference can make the difference between a good and a excellent espresso.

The Pump

In contrast to piston machines that are manually operated, that use a lever to pressurize water, the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger before it is shot through the ground coffee in the group head.

Pumps are generally more affordable and last longer than piston-driven machines. However, both kinds of machines may degrade because of frequent use and inadequate cleaning. Pumps are also more complex mechanically, which could increase prices of even simpler models.

Certain espresso machines remove the pump completely and employ steam pressure to create espresso. This can lead to over-extraction as the boiler that produces steam also causes the water to boil. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

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

The Boiler

The boiler makes the water warm to the perfect temperature for extraction. The steam that is produced reaches the portafilter containing the ground espresso and is then pumped down into the cup. In this process, the steam creates pressure and pushes through the grounds of the coffee. This results in a layer of crema on top. This is a hallmark of a great espresso.

There are three types of espresso makers, and they differ in the type of pump they use and how hot the coffee is. There are various ways in which the brew could be controlled, as well as the size of the cup that the maker can create.

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

The most common espresso machine is a semiautomatic model with an electric pump. These are what people imagine when they think of an espresso maker. With a semi-automatic machine you need to grind the beans and tamp them yourself but the pump is able to regulate the flow of water and pressure. This is a fantastic combination of human control and mechanized accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from hot water. The filter is also an essential element of the machine's temperature control, as it helps prevent overheating.

A filter can also help with flavor since it allows for the beans to flower for a longer period of time. This allows the beans to let their nuances out, and also allows for better extraction.

However it is crucial to keep in mind that even a good filter can result in a poor cup of coffee, because the quality of the beans and extraction is important.

It's here that the magic occurs. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you place the portafilter, the device which you put the grounds of your coffee into while making espresso.

In a steam-driven cheap espresso machine machine hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds at a high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pump-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. While the perfect shot requires 9 bar espresso machine-10 bar.

In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They use an air compressor to push hot water across the ground and are more mobile than electric steam-driven espresso machines.