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How Does Machine Espresso Work?

Machine espresso employs precise pressure and amazing filter technology to make the coffee we love. How does it work exactly?

In order to make espresso, hot water is forced under high pressure through finely ground coffee for espresso machine. The process is similar to making drip coffee. However the pressure is the primary difference.

The Group Head

The group head is the portafilter that is inserted when you are making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the resulting extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some are specifically designed for the stability of temperature while some are designed to handle pre-infusion. Others are built to control the lever. Some are a combination, like the E61. This is a popular choice among baristas since it provides multiple advantages in one package.

As you can see in the image above The group head features many notches in which you can place your portafilter and then twist it manually to secure it. A gasket of rubber is situated within the notches to create a seal as you insert your portafilter. The notches permit precise placement of your portafilter. This is crucial for an accurate extraction.

Apart from allowing you easily insert your portafilter, the group head is responsible for maintaining an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is constant to extract the coffee. This is crucial, since even a small difference in temperature can make the difference between a excellent and great 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 required to extract espresso. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee inside the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both types of machines may degrade due to excessive use and inadequate cleaning. Pumps are also more complicated mechanically, and can add to the cost of even the simple models.

Some espresso machines use steam pressure instead of a pump to brew espresso. This can lead to over-extraction as the dual boiler espresso machine that makes steam also warms the water to boil. In addition the machines often have to restore their pressure between cups, which takes time and energy.

Many espresso machines use a rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, while the rotating model pushes hot water through the ground at a high speed. Both types of machines can make excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The dual Boiler espresso Machine heats the water to the right temperature for extraction. The steam that is produced is then directed to the portafilter, which contains the best budget espresso machine coffee grounds. The steam is then channeled into the cup. During this process the steam generates enough pressure to push the coffee grounds through. This results in a whipped-up top of the espresso. This is a sign of a good espresso.

There are three distinct types of espresso machines, each with distinct pumps and the temperature of the brew. 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 earliest espresso machines were steam types. They utilized one boiler to make both brew and steam, however the pressure they were able to produce was not very high - two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso maker is a semi-automatic device with an electric pump. These are what people imagine when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans yourself while the pump controls the flow of water and pressure. This is an excellent compromise between human touch and the mechanised accuracy.

The Filter

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

It also helps with flavor, since a filter lets you enjoy a longer bloom time. This allows the beans to let their nuances out and provides an opportunity for better extraction.

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

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

Steam-driven espresso machines use hot water heated in an airtight container to make steam. The steam then pushes hot water into the grounds of coffee under high pressure. These types of machines are generally less expensive and simpler to maintain than pump-driven models. They are however limited in their ability to create the perfect brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to push hot water into the grounds and are significantly more portable than steam-driven electric machines.