How Does Machine Espresso Work?

Machine espresso employs precise pressure and amazing filter technology to make the delicious coffee we enjoy. What exactly is it that makes it work?

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

The Group Head

The group head is the portafilter that you place in the espresso maker when making it. It is responsible for dispersing water into the portafilter before controlling the pressure of the extraction. There are many different types of group heads, each with its own advantages and disadvantages. Some are focused on temperature stability, while others on pre-infusion capabilities, while others are designed to control the lever. Some come with a combination of both, such as the E61. This is a favorite among baristas because it offers multiple benefits in one package.

As you can see in the photo above the group head is made up of several notches where you place your portafilter and twist it with your hands to secure it. There is also a gasket made of rubber that resides inside the notches and helps create the seal when you insert your portafilter into the machine. The notches permit 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 to maintain an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is always at the right level for extraction. It is important to remember that even a slight difference can make the difference between a decent and a great espresso.

The Pump

Contrary to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure necessary for espresso extraction. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be cheaper than piston-driven machines, and they tend to last longer, but both types of machines may degrade with overuse and insufficient cleaning. They also add mechanical complexity and can lead to a high price tag on even the simplest models.

Certain espresso machines eliminate the pump completely and instead utilize steam pressure to make espresso. The downside is that the boiler that produces steam also increases the temperature of the water until it reaches boiling which could lead to excessive extraction. In addition these machines typically have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines employ a vibration or rotary pump, which is a vibration model that uses a vibrating disc to create pressure and an rotary model that pushes hot water through the grounds under high speed. Both types of machine can produce an excellent espresso, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is what is used to heat the water to the ideal temperature to extract. The resulting steam is then transferred to the portafilter which holds the ground espresso coffee, and is then funneled down into the cup. The steam creates enough pressure to push the coffee grounds 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 different types of espresso machines, each with a different type of pump and the temperature of the brew. There are a variety of ways in which the brew could be controlled and the size of the cup the maker can create.

The earliest espresso machines were steam-based. The first espresso machines were steam-type machines. This resulted in the coffee tasting bitter and burnt. This is the reason Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern professional espresso machine for home machine.

The most commonly used espresso machine is a semiautomatic that has an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic espresso machine (www.tolstory.com), you need to grind the beans and then tamp them yourself but the pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and mechanized consistency.

The Filter

Typically, espresso machines utilize filters to separate the coffee grounds as they pass through the hot water. The filter is also an essential element of the machine's temperature control, as it prevents overheating.

A filter also improves flavor, as it permits a longer flowering phase. This helps the beans to let their nuances out and provides an opportunity for better extraction.

It is important to remember that even the finest filter can result in a bad cup of coffee. The quality of the beans and the extraction process, are still very important.

It's in this area that the magic happens. This is what makes espresso taste so delicious. The grouphead (also known as the brewhead) is where you place the portafilter, the thingy that you put the grounds of your coffee into when making buy espresso makers.

In a steam-driven espresso machine hot water is heated in an airtight container to create steam. This then pushes the hot water through the grounds under high pressure. They are less expensive and easier for the user to maintain than pumps-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 perfect shot requires 9-10 bars.

In recent years, compressed air pump-driven espresso machines have been gaining popularity. They utilize an air compressor to push hot water through the ground, and are more mobile than electric steam-driven espresso machines.

좋아요 0