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How Does Machine Espresso Work?

Machine espresso uses precision pressure and amazing filter technology to make the coffee we love. What exactly is it that makes it work?

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

The Group Head

The group head is the portafilter you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter, espresso maker and controlling the pressure of the extraction. There are various kinds of group head each with its own advantages and disadvantages. Some are designed to provide temperature stability while others are built to handle pre-infusion. Some are designed to control the lever. Some have a combination, like the E61. This is a very popular choice for baristas since it provides multiple advantages in a single package.

As you can see from the above photo the head of the group is fitted with several notches. You can place your portafilter in these notches, then twist the head to lock it. There is also a gasket made from rubber in the notches and helps to create the seal when you insert your portafilter into the machine. The notches on the head permit a precise positioning of the portafilter which is vital to ensure a consistent extraction.

In addition to allowing you easily connect your portafilter, the group head is responsible for maintaining a consistent temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, ensuring the temperature is always right for extraction. It is important to realize that even a slight difference can make the difference between a good and a excellent espresso machine black friday.

The Pump

In contrast to manual piston machines which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to deliver the nine atmospheric bars of pressure required to extract mini espresso machine. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior to it is shot through the ground coffee inside the group head.

Pumps tend to be more affordable and last longer than piston-driven machines. However, both types of machines may degrade because of frequent use and insufficient cleaning. Pumps are also more complex mechanically, which could increase the cost of even simpler models.

Some espresso machines do away with the pump completely and employ steam pressure to create espresso. The drawback is that the same boiler that produces steam also raises the temperature of water to boiling which could lead to excessive extraction. In addition these machines typically have to restore their pressure between cups, which takes time and energy.

A large majority of espresso machines employ a rotary or vibration pump. A vibration model employs the vibrating disk to create pressure, while a Rotary model pushes hot coffee through the ground at a fast speed. Both types of machines can make 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 optimal temperature to extract. The resultant steam then reaches the portafilter containing the ground espresso coffee and gets funnelled down into the cup. In this process, the steam creates pressure that pushes through the coffee grounds. This results in a layer crema on top. This is one of the hallmarks of a good espresso machine coffee.

There are three kinds of espresso makers, and they differ in the kind of pump they use and how hot the brew is. There are various ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.

The first espresso machines were steam-based. They utilized a single boiler to make both steam and brew but the pressure they could produce was very low - just two bars of atmospheric pressure at most. The coffee tasted bitter and burned. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most commonly used espresso home machine maker is a semi-automatic machine that has an electric pump. These are the images people have when they think of an espresso maker. If you have a semi-automatic machine you grind the beans and then tamp them by hand. However, the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and the mechanized accuracy.

The Filter

Typically, espresso machines have a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also a crucial element of the temperature control system, as it keeps the machine from overheating.

Filters also aid in flavor because it allows for an extended flowering time. This helps the beans release their nuances and gives an opportunity for a better extraction.

However it is crucial to remember that even a good filter can make a terrible cup of coffee, as the quality of the beans and extraction are essential.

This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead, also referred to as the brewhead, is where the portafilter (the thing you put the ground coffee in) is placed when you're making espresso.

Steam-driven espresso machines use hot water that is heated inside an airtight container to make steam. The steam then pushes hot water into the grounds of coffee under high pressure. These kinds of machines are usually less expensive and simpler to maintain than pump-driven models. However, they are limited in their ability to produce the perfect conditions for brewing, since they are only operating at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

In recent years, compressed air pump-driven espresso machines have become more popular. They use an air compressor to push hot water through grounds and are more portable than steam-driven electric machines.