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How Does Machine Espresso Work?

Machine espresso uses precision pressure and incredible filter technology to produce the perfect cup of coffee. But how exactly does it work?

Espresso is produced by pushing 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

The group head is the portafilter you insert when brewing espresso. It disperses water in the portafilter, and then regulates the pressure of extraction. There are various kinds of group head, each with their particular advantages and drawbacks. Some are specifically designed for stability of temperature while others are specifically designed to handle pre-infusion. Others are made to control the lever. Some include a combination like the E61. This is a popular choice among baristas since it provides multiple benefits in one package.

As you can see in the photo above The group head features numerous notches that you can place your portafilter and then twist it manually to secure it. A gasket of rubber is situated inside the notches to help create a seal while you insert your portafilter. The notches allow for an exact placement of the portafilter. This is vital for an even extraction.

The group head not only allows you to insert your portafilter easily but also maintains the same temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is at the right level for extraction. This is vital, because even a few degrees can make the difference between good and great cheap espresso machine.

The Pump

Contrary to manual piston machines which rely on a lever to pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure necessary to extract espresso. The pressure is created by drawing 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 cheaper than piston-driven machines, and they tend to last longer. However, both types of machines can degrade with overuse and insufficient cleaning. Pumps are also more complex mechanically, which can raise the cost of even the most basic models.

Some espresso machines can eliminate the pump entirely and make use of steam pressure to make espresso. The drawback is that the same boiler that produces steam also increases the temperature of the water until it reaches boiling and can result in over-extraction. The machines also need to constantly rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize the rotary or vibration pump, which has a vibration model using a vibrating disc that generates the pressure, and rotating models that push hot water through the grounds at high speed. Both models are capable of producing excellent espresso, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler heats the water to the right temperature for extraction. The steam that is produced reaches the portafilter which holds the ground espresso coffee, and is then pumped down into the cup. The steam causes enough pressure to push the grounds of coffee through. This results in a crema on the top of the espresso. This is a sign of a great espresso.

There are three kinds of espresso makers. They differ in the kind of pump they use and how hot the espresso is. There are various 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-type. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic with an electric pump. These are the images people have when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans on your own The pump, however, regulates the water flow and pressure. This is an excellent combination of human control and mechanized reliability.

The Filter

Typically, espresso machines utilize filters that separate the grounds of coffee when they pass through the hot water. The filter is also a vital component of the machine's temp control, since it stops overheating.

It also aids in flavor, since a filter allows for a more prolonged bloom time. This allows the beans to release their flavors, and allows for a better extraction.

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

It's in this area that the magic takes place. This is what makes espresso taste so good. The grouphead (also called the brewhead) is where you put the portafilter - the thingy which you put the grounds of coffee into when making espresso.

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

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