A Provocative Rant About Machine Espresso

How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to make the coffee we love. What exactly is it?

Espresso is produced by pushing hot water under pressure through finely ground coffee. The process is similar to making drip coffee. However, the pressure is the main difference.

The Group Head

As the name suggests the group head is the place you place your portafilter when making espresso. It disperses water in the portafilter and regulates the pressure of the extraction. There are a variety of types of group head, each with their distinct advantages and drawbacks. Some are specifically designed for temperature stability while others are built to handle pre-infusion. Some are designed to control the lever. There are some that include a mix of features, such as the E61 that is the classic choice among many baristas because of its ability to offer multiple perks in one package.

As you can see from the picture above, the group head is fitted with a variety of notches. The portafilter is placed in these notches, then twist the head to lock it. A gasket of rubber is situated within the notches to make a seal when you insert your portafilter. The notches on the head allow for a precise positioning of the portafilter which is necessary to ensure an efficient extraction.

The group head not only allows the portafilter to be inserted easily however it also keeps the same temperature. It does this by circulating hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature for extraction. This is vital, because even a few degrees can make the difference between excellent and great espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure required to extract espresso. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines can deteriorate because of frequent use and inadequate cleaning. Pumps are also more complex mechanically, which can increase prices of even simple models.

Some espresso machines can eliminate the pump completely and use steam pressure to brew espresso. This could lead to over-extraction since the boiler that produces steam also causes the water to boil. They also have to constantly rebuild their pressure between cups. This takes energy and time.

A large majority of espresso machines espresso machines employ an rotary or a vibration pump. A vibration model makes use of an oscillating disk to create pressure, whereas the circular model pushes hot liquid through the ground at a rapid speed. Both machines can produce excellent espresso, however rotary machines are more stable, quieter and less likely to break down.

The Boiler

The boiler heats the water to the right temperature for extraction. The resulting steam is then transferred to the portafilter, which contains the ground espresso coffee, and is then pumped down into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This results in a layer crema on top. This is one of the main characteristics of a great espresso.

There are three kinds of espresso home machine machines, each with different pumps and brew temperature. There are various ways in which the brew can be controlled, as well as the size of the cup that the machine is capable of making.

The first best small espresso machine machines were steam type. They employed only one boiler to make both steam and brew, however, the pressure they could create was minimal - two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most common best espresso machine under 500 machine is a semiautomatic model with an electric pump. These are the images people have when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself The pump, however, regulates the water flow and pressure. This is an excellent compromise between human touch and the mechanised consistency.

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 an essential component of the machine's temp control, as it prevents overheating.

A filter also improves flavor since it allows for a longer flowering period. This helps the beans let their nuances out and provides an opportunity for better extraction.

However, it is important to keep in mind that even a top filter could result in a bad cup of coffee as the quality of the beans and extraction are vital.

It's in this area that the magic takes place. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you put the portafilter, the device used to place the grounds of your coffee into while making espresso.

Steam-driven espresso Machines Espresso machines use hot water that is heated in an airtight vessel to create steam. The steam then pushes hot water into the grounds of the coffee under pressure. These types of machines are typically less expensive and easier to maintain than pump-driven models. They are however limited in their ability for creating the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, espresso machines driven by compressed air-pump are becoming increasingly popular. They make use of an air compressor to force hot water into the ground and are much more mobile than steam-driven electric espresso machines.