9 Lessons Your Parents Taught You About Machine Espresso > 자유게시판

How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and amazing filter technology to make the coffee we love. How does it work exactly?

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

The Group Head

As the name implies, the group head is the place you insert your portafilter when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the resulting extraction. There are a variety of group heads, each with its own advantages and disadvantages. Some are designed to provide stability of temperature while others are designed to handle pre-infusion. Some are designed to control the lever. Some come with a combination of both, like the E61. This is a very popular choice for baristas as it provides a variety of benefits in one package.

As you can see in the image above, the group head has several notches to place your portafilter and then twist it by hand to secure it. There is also a rubber gasket that resides inside the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches permit an exact placement of the portafilter. This is crucial to ensure an accurate extraction.

Apart from allowing you effortlessly insert your portafilter the group head is responsible to maintain an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is always at the right level for extraction. This is vital, because even a few degrees can make the difference between excellent and great best home espresso machine.

The Pump

The motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure needed for espresso extraction. This differs from manual piston machines which use levers. The pressure is built by pumping water through a heat exchanger and then through the ground coffee.

Pumps are generally less expensive than piston-driven models, and they tend to last longer, but both types of machines could become damaged due to excessive use and poor cleaning. They also increase the complexity of mechanical systems that can lead to a high price tag on even the simplest models.

Some espresso machines remove the pump completely and instead make use of steam pressure to make espresso. This can result in over-extraction because the boiler that makes steam also causes the water to boil. Additionally the machines often have to rebuild their pressure between cups, which takes time and energy.

Many espresso machines employ the rotary or vibration pump, with a vibration model using a rotating disc that generates the pressure and the rotary model pushing hot water through the grounds at high speed. Both machines can make excellent espresso however rotary machines tend to be more stable, quieter and less likely to fail.

The Boiler

The boiler is the part that heats the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter that contains the ground cafe espresso machine coffee and is then pumped down into the cup. The steam creates enough pressure to push the grounds of the coffee and espresso maker through. This results in a layer of crema that is then poured over. This is a hallmark of a great retro espresso machine.

There are three distinct types of espresso machines, each with distinct pumps and the temperature of the brew. There are various ways in which the brew could be controlled, as well as the dimensions of the cup the machine can make.

The earliest espresso machines were steam types. They had one boiler to make steam and brew, however, the pressure they could create was minimal - two bars of atmospheric pressure, at most. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most popular espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine you grind the beans and tamp them yourself but the pump provides regulated water flow and pressure. This is a great combination of human control and mechanised consistency.

The Filter

Typically, espresso machines employ filters that separate the grounds of coffee as they move through the hot water. The filter is also a crucial component of the temperature control system as it keeps the machine from overheating.

A filter can also help with flavor since it allows for a longer flowering phase. This allows the beans to let their nuances out, and also allows for better extraction.

However it is crucial to remember that even a top filter can produce a bad cup of coffee as the quality of the beans and extraction is crucial.

It's in this area that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, also referred to as the brewhead, is where the portafilter (the device you put the coffee and espresso maker ground into) is located when you're making espresso.

Steam-driven espresso machines make use of hot water that is heated in an airtight container to produce steam. The steam then pushes hot water through the grounds of the coffee under pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. They are however limited in their ability to create 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 force hot water into the grounds and are more portable than electric steam-driven machines.