How Does Machine Espresso Work?
The machine espresso uses precise pressure and filter technology that is awe-inspiring to make the coffee you 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 implies the group head is the place you insert your portafilter when brewing espresso. It disperses the water into the portafilter, and then regulates the pressure of extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. Some come with a combination of both, such as the E61. This is a favorite among baristas as it provides a variety of advantages in one package.
As you can see from the photo above the group head has a number of notches. You place your portafilter in these notches, then twist the head to lock it. A rubber gasket is located in the notches to create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is vital for a consistent extraction.
Apart from allowing you easily connect your portafilter, the group head is also responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew basket and around the portafilter to ensure that it is always at the right temperature to extract. This is important, as even a few degrees can mean the difference between good and excellent espresso.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to deliver 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 tend to be less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading because of excessive use and poor cleaning. They also add mechanical complexity, which can result in an expensive price for even the most basic models.
Some espresso machines make use of steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that makes steam also heats the water to boil. In addition these machines typically have to restore their pressure between cups, which takes time and energy.
A majority of espresso machines use a vibration or rotary pump, with a vibration model using a vibrating disc to generate the pressure and an rotary model that pushes hot water through the grounds at high speed. Both types of machines can produce an excellent espresso, however the rotary models are quieter and more durable than vibration pumps.
The Boiler
The boiler is the one that makes the water warm to the ideal temperature to extract. The steam that is produced will eventually reach the portafilter, which is a container for espresso grounds. It website is then pumped into the cup. The steam creates pressure check here to push through the coffee grounds. This results in a layer of crema that is then poured over. This is the hallmark of a good espresso.
There are three kinds of espresso machines, each with a different type of pump and brew temperature. There are different ways in which the brew can be controlled, as well as the size of the cup that the machine can produce.
The earliest espresso machines were steam type. The earliest espresso website machines were steam-type machines. The coffee tasted bitter and burned. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most commonly used espresso maker is a semi-automatic machine with an electric pump. These are the images people have when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the water flow and pressure. This is a great compromise between the human website touch and mechanized accuracy.
The Filter
Espresso machines usually have filters that separate the grounds of the coffee from hot water. The filter is also a vital component of the machine's temperature control, since it helps to prevent overheating.
A filter also improves flavor because it allows for an extended flowering time. This allows the beans to release their flavors, and allows for a better extraction.
It is important to remember that even the most efficient filter could result in a poor cup of coffee. The quality of the beans, and the extraction process, are still very important.
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 brew head, is where the portafilter (the container you place the coffee grounds into) is placed when making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then moves here hot water through the grounds of coffee under high pressure. These types of machines are typically less expensive and simpler to maintain than pump-driven models. They are however limited to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent times, espresso machines powered by compressed air-pump are becoming increasingly popular. They use an air compressor to push hot water through the ground and are much more mobile than electric steam-driven espresso machines.