• 목록
• 답변
• 글쓰기
• 게시판 리스트 옵션
  • 수정
  • 삭제

How Does Machine Espresso Work?

The machine espresso uses precise pressure and filtering technology that is amazing to make the coffee you love. How does it work exactly?

Espresso is made by pushing hot water under pressure through finely-ground coffee. The process is similar to that of making drip coffee. However the pressure is the main difference.

The Group Head

As the name implies, the group head is the place you put your portafilter in when brewing espresso. It disperses the water into the portafilter, and then regulates the pressure of extraction. There are several different types of group heads, each with their distinct advantages and disadvantages. Some are specifically designed for stability in temperature, while others are built to handle pre-infusion. Some are designed to control the lever. Some have a combination of features, such as the E61, which is considered the standard choice for many baristas because of its ability to provide multiple benefits in a single package.

As you can see from the image above the group head is equipped with several notches. You place your portafilter inside these notches, and then turn the head around to secure it. A rubber gasket is located in the notches to create a seal when you insert your portafilter. The notches on the head allow for an exact placement of the portafilter, which is essential for an efficient extraction.

Apart from allowing you easily insert your portafilter, the group head is also responsible to maintain an even temperature. It does this by circulating hot water through the brew pan and around the portafilter, ensuring that it's always at the right temperature for extraction. This is important, as even a small difference in temperature can make the difference between a good and excellent espresso machines home.

The Pump

The motorized pumps used in espresso machines rotary provide nine atmospheric bars of pressure required to extract espresso. This differs from manual piston machines which use a lever. The pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee in the group head.

Pumps tend to be cheaper than piston-driven machines and tend to last longer, but both types of machines may become damaged due to excessive use and poor cleaning. Pumps are also more complex mechanically, which can raise the cost of even simpler models.

Certain espresso machines do away with the pump completely and make use of steam pressure to make espresso. The disadvantage of this is that the same boiler that produces steam also raises the temperature of the water until it reaches boiling which could lead to excessive extraction. Additionally, these machines frequently have to restore their pressure between cups, which requires time and energy.

Many espresso machines use a rotary or vibration pump. A vibration model uses a vibrating disk to generate pressure, whereas a Rotary model pushes hot coffee through the ground at high speed. Both machines can make excellent espresso, however rotary machines are quieter, more durable and less likely to break down.

The Boiler

The boiler is the element which heats the water to the ideal temperature for extraction. The resulting steam reaches the portafilter that contains the ground espresso coffee and gets funnelled down into the cup. During this process the steam creates enough pressure to push the coffee grounds through. This produces a layer of crema on top. This is one of the hallmarks of a good espresso.

There are three types of espresso makers. They differ in the type of pump they use and how hot the coffee is. There are also different ways that the brew can be controlled and the dimensions of the cup the machine can produce.

The first espresso machines were steam type. They utilized one dual boiler espresso machine to make both steam and brew, but the pressure they could produce was very low - just two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semi-automatic machine with an electric pump. These are the things people think of when they think of an Italian espresso machines machine. With a semi-automatic machine you grind the beans and tamp them yourself but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanised quality.

The Filter

Typically, espresso machines use filters that separate the grounds of the coffee as they go through the hot water. The filter is also an essential component of the machine's temp control, since it stops overheating.

A filter can also help with flavor, as it permits the beans to flower for a longer period of time. This helps the beans to let their nuances out and provides an opportunity to improve extraction.

However it is crucial to keep in mind that even a good filter could result in a bad cup of coffee, since the quality of the beans and extraction is still crucial.

It's here that the magic happens. This is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you place the portafilter, the device which you put the coffee grounds into, when making espresso.

Steam-driven espresso machines use hot water that is heated in an airtight container to produce steam. The steam then pushes hot water through the grounds of coffee under high pressure. They are less expensive and easier for the user to maintain than pumps-driven models. They are however limited to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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