Nine Things That Your Parent 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 perfect cup of coffee. What exactly does it work?

To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference.

The Group Head

The group head is the portafilter you insert when brewing espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the extraction. There are several different types of group head, each with their distinct advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion options, and others are designed to control the lever. Some come with a combination of both, such as the E61. This is a preferred choice for baristas because it offers multiple advantages in one package.

As you can see in the above image The group head features many notches in which you can place your portafilter and then twist it with your hands to lock it in. There is also a gasket made from rubber that resides inside the notches to help create an airtight seal when you insert your portafilter into the machine. The notches on the head allow for an exact placement of the portafilter, which is necessary for a consistent extraction.

The group head not only lets you to put in your portafilter easily, but it also maintains a constant temperature. It does this by cycling hot water through the brew basket, and around the portafilter, ensuring that it's always at the correct temperature for extraction. This is crucial, since just a few degrees could mean the difference between good and great espresso.

The Pump

Contrary to manual piston machines that use a lever to pressurize water, the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure needed for espresso extraction. The pressure is built 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, although both types of machine can get damaged through overuse and lack of cleaning. Pumps are also more complicated mechanically, which could increase prices of even most basic models.

Some espresso machines make use of steam pressure instead of a pump to make espresso machine coffee. This can lead to over-extraction as the boiler that makes steam also heats the water to boil. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

A majority of espresso machines use the rotary or vibration pump, which is a vibration model using a vibrating disc that generates the pressure and the rotary model pushing hot water through the grounds under high speed. Both types of machines can produce an excellent espresso, however Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the component that heats the water to the ideal temperature to extract. The steam that is produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then funneled into the cup. During this process the steam creates enough pressure to push the grounds of the coffee through. This results in a layer of crema on top. This is the hallmark of a good espresso.

There are three distinct types of espresso machines, each having different types of pumps and brew temperature. There are many ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam type. They employed one dual boiler espresso machine to create both steam and brew however the pressure they were able to create was minimal - two bars of atmospheric pressure at most. This led to the coffee tasting bitter and burnt. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso maker is a semi-automatic machine that has an electric pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you bean to cup espresso machine grind and tamp your beans yourself, but the pump regulates the water flow and pressure. This is a great compromise between the human touch and the mechanized consistency.

The Filter

Espresso machines usually have a filter that separates the grounds of the coffee from hot water. The filter is also a vital element of the temperature control system, as it keeps the machine from overheating.

It also helps with flavor, as a filter can allow for a longer bloom phase. This allows the beans to release their flavor and also allows for better extraction.

It is important to keep in mind that even the finest filter can result in a bad cup of coffee. The quality of the beans and the extraction process, remain vital.

It's in this area that the magic takes place. This is the reason why espresso tastes so good. The grouphead, also referred to as the brewhead, is where the portafilter (the thing you put the coffee ground into) is placed when making espresso.

Steam-driven 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 machines are less expensive and easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

In recent years, compressed air-pump-driven espresso machines have become more popular. They make use of an air compressor to push hot water through the ground. They are also more mobile than electric steam-driven espresso machines.