9 Lessons Your Parents Taught You About Machine Espresso > 자유게시판

How Does Machine Espresso Work?

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

To make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee but the major difference is in the pressure.

The Group Head

As the name suggests, the group head is the place you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are a variety of group heads, each with its own advantages and disadvantages. Some are specifically designed for stability in temperature, while others are specifically designed to handle pre-infusion. Some are designed to control the lever. There are even some that have a combination of features, such as the E61 one, which is the standard choice for many baristas due to its ability to provide multiple benefits in a single package.

As you can see in the above image, the group head has many notches in which you can place your portafilter and then twist it by hand to secure it. A gasket of rubber is situated inside the notches, which helps create a seal when you insert your portafilter. The notches on the head permit a precise location of the portafilter which is essential for an efficient extraction.

In addition to allowing you to effortlessly insert your portafilter the group head is responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew basket, and around the portafilter, making sure that it's always at the right temperature to extract. It is important to remember that even a few degree differences can make the distinction between a good and a excellent espresso machine with frother.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotating espresso machines rely upon motorized pumps to supply the nine atmospheric bars of pressure needed to extract espresso. The pressure is created by pumping water through a heat exchanger and then through the ground coffee.

Pumps are typically less expensive than piston-driven machines, and tend to last longer, although both types of machine can get damaged through overuse and lack of cleaning. They also add mechanical complexity which can result in the cost of even the simplest models.

Some espresso machines eliminate the pump completely and utilize steam pressure to make espresso machines home. The drawback of this is that the same boiler that produces steam also raises the temperature of water until it reaches boiling, which can lead to over-extraction. They also have to constantly rebuild their pressure in between cups. This requires energy and time.

Many espresso machines make use of a rotary or vibration pump. A vibration model utilizes the vibrating disk to create pressure, whereas a Rotary model pushes hot coffee through the ground at a rapid speed. Both models can make a great espresso, but rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats water to an optimal temperature to extract. The steam that is created is then directed to the portafilter, which is a container for espresso grounds. It is then funneled into the cup. The steam generates enough pressure to push the grounds of the coffee through. This creates a crema on top of the espresso. This is one of the main characteristics of a good espresso machines for home.

There are three kinds of espresso machines, each having different types of pumps and the temperature of the brew. There are a variety of ways to control the brew as well as the size of cup that can be produced by the machine.

The first 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 the most. The coffee tasted bitter and burnt. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most common espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic machine, you need to grind the beans and tamp them by hand, but the pump regulates the flow of water and pressure. This is a perfect compromise between human control and mechanised reliability.

The Filter

Espresso machines typically use filters that separate the grounds of the coffee from hot water. The filter is also a vital component of the temperature control system, because it stops the machine from overheating.

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

It is important to keep in mind that even the best filter could result in a poor cup of coffee. The quality of the beans, as well as the extraction, are still crucial.

This is where the magic happens, and it's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you put the portafilter - the thingy used to place the coffee grounds in, when making espresso.

Steam-driven espresso machines make use of hot water heated in an airtight container to produce steam. The steam then pushes hot water through the coffee grounds under high pressure. These kinds of machines are typically cheaper and easier to maintain than pumps-driven models. They are however limited to create 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 powered by a compressed air pump have become increasingly popular. They utilize an air compressor to push the hot water through the grounds, and are far more portable than steam-driven electric machines.