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How Does Machine Espresso Work?

The machine espresso uses precision pressure, and filter technology that is mind-blowing to make the coffee you enjoy. What exactly is it that makes it work?

Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.

The Head of the Group

The group head is the portafilter that is inserted when you are making espresso. It disperses water in the portafilter, and controls the pressure of the extraction. There are many different kinds of group head, each with their unique advantages and drawbacks. Some are specifically designed for temperature stability while others are built to handle pre-infusion. Others are made to control the lever. There are even some that come with a range of features, such as the E61, Best espresso maker which is the most popular choice among baristas due to its capacity to offer multiple perks in a single package.

As you can see in the image above, the group head has several notches where you place your portafilter and twist it with your hands to lock it in. There is also a gasket of rubber that resides inside the notches and helps create the seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is essential for an efficient extraction.

Apart from allowing you effortlessly insert your portafilter the group head is also responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew basket, and around the portafilter, ensuring that it is always at the right temperature to extract. It is crucial to keep in mind that even a few degree differences can make the distinction between a good and portable great espresso.

The Pump

The motorized pumps used in rotary espresso machines provide the nine atmospheric bars of pressure required for espresso extraction. This differs from manually operated piston machines that employ a lever. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee in the group head.

Pumps are typically less expensive than piston-driven machines, and they tend to last longer. However, both types of machines can degrade with overuse and insufficient cleaning. They also create mechanical complexity which can result in the cost of even the simplest models.

Some espresso machines remove the pump entirely and employ steam pressure to create espresso. This can cause over-extraction because the boiler that produces steam also heats the water to boil. These machines also have to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines employ either a rotary or vibration pump, which has a vibration model using a vibrating disc to generate the pressure and rotating models that push hot water through the grounds at high speed. Both types of machines can make a great espresso, however the rotary models 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 that contains ground espresso beans and is then funneled down into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This results in a crema on the top of the espresso. This is one of the hallmarks of a good espresso.

There are three kinds of espresso makers. They differ in the type of pump they employ and how hot the brew is. There are also different ways that the brew can be controlled and the size of the cup the maker can create.

The earliest espresso machines were steam types. They had one boiler to make both steam and brew however, the pressure they could produce was not very high - two bars of atmospheric pressure at most. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semi-automatic one with an electric pump. These are what people imagine when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the water flow and pressure. This is an excellent combination of human control and mechanized consistency.

The Filter

Typically, espresso machines use a filter to separate out the grounds of the coffee as they go through the hot water. The filter is also an essential part 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 phase. This allows the beans to let their nuances out, and allows for a better extraction.

It is important to keep in mind that even the most efficient filter can result in a bad cup of coffee. The quality of the beans as well as the extraction, are still crucial.

This is where the magic happens, it's the thing that makes an espresso really taste good. The grouphead (also called the brewhead) is where you put the portafilter, the thingy that you put the coffee grounds in, while making espresso.

In the steam-driven espresso machine hot water is heated in an airtight tank to create steam. This then pushes the hot water through the grounds at high pressure. These types of machines are generally cheaper and easier to maintain than pump-driven models. They are however limited to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.