How Does Machine Espresso Work?
The machine espresso is made using precision pressure, and a filtering technology that is amazing to create the coffee you enjoy. How exactly does it work?
In order to make 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 Head of the Group
The group head is the portafilter that you put in when making espresso. It is responsible for dispersing water into the portafilter, and controlling the pressure of the extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some are designed to provide stability in temperature, while others are designed to handle pre-infusion. Some are designed to control the lever. Some come with a combination of both, such as the E61. This is a popular choice among baristas because it offers multiple benefits in one package.
As you can see from the image above the head of the group is equipped with several notches. You can place your portafilter into these notches and twist the head to lock it. There is also a rubber gasket that is a part of the notches to help create an airtight seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is crucial for an accurate extraction.
Aside from allowing you to easily connect your portafilter, the group head is also responsible for maintaining an even temperature. This is accomplished 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. It is important to remember that even a slight deviation can make the difference between a good and excellent espresso.
The Pump
In contrast to manual piston machines which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by removing tap water from a reservoir, and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.
Pumps tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and poor cleaning. They also make mechanically complex which can result in a high price tag on even the most basic models.
Some espresso machines make use of steam pressure instead of a pump in order to brew espresso. The downside is that the same boiler that produces steam also raises the temperature of the water to boiling which can cause over-extraction. The machines must also continually rebuild their pressure between cups. This requires energy and time.
A majority of espresso machines use an rotary or vibrating pump, which has a vibration model that uses a vibrating disc to generate the pressure and a rotary model pushing hot water through the grounds at 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 makes the water warm to a temperature that is ideal to extract. The resulting steam is then transferred to the portafilter that contains ground espresso beans and is then pumped into the cup. In this process, the steam creates pressure to push through the coffee grounds. This results in a layer crema on top. This is one of the hallmarks of a great espresso.
There are three types of espresso makers, and they differ in the type of pump they employ and the degree of heat that the coffee is. There are a variety of ways that the brew may be controlled, as well as the size of the cup that the machine can produce.
The earliest espresso machines were steam type. espresso coffee machine Coffeee were steam types. The coffee tasted bitter and burned. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most well-known espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized 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 vital component of the temperature control system, since it helps prevent the machine from overheating.
A filter also improves flavor because it allows for a longer flowering period. This allows the beans to let their nuances out, and improves extraction.
It is important to remember that even the best filter can make a bad cup of coffee. The quality of the beans, and the extraction process, are still crucial.
It's here that the magic occurs. This is what makes espresso taste so good. The grouphead, also referred to as the brew head, is the place where the portafilter (the device you put the ground coffee into) is located when you're making espresso.
In a steam-driven espresso machine hot water is heated in an airtight container to produce steam, which then pushes the hot water through the grounds at high pressure. These types of machines are typically less expensive and easier to maintain than pump-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, espresso machines driven by a compressed air compressor have become increasingly popular. They use an air compressor to push hot water through the ground and are more mobile than electric steam-driven espresso machines.