How Does Machine Espresso Work?
Machine espresso, 79bo.cc, utilizes precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly is it?
To make espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the major difference.
The Head of the Group
The group head is the portafilter you put in when making espresso. It disperses the water into the portafilter and regulates the pressure of extraction. There are many different kinds of group heads, each with their particular 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 include a combination like the E61. This is a preferred choice for baristas because it offers multiple advantages in one package.
As you can see in the image above The group head features several notches where you place your portafilter and twist it by hand to secure it. There is also a rubber gasket in the notches and helps create an airtight seal after inserting your portafilter into the machine. The notches on the head permit an exact position of the portafilter which is vital to ensure an even extraction.
Aside from allowing you to easily connect your portafilter, the group head is responsible for maintaining a consistent temperature. It does this by cycling hot water through the brew pan and around the portafilter, ensuring that it is always at the correct temperature to extract. This is crucial, since even a few degrees can mean the difference between good and great espresso.
The Pump
The motorized pumps used in rotary espresso machines supply the nine atmospheric bar pressure required to extract espresso. This is different from manually operated piston machines that employ levers. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are typically less expensive and last longer than piston-driven machines. However, both types of machines can degrade due to overuse and inadequate cleaning. Pumps are also more complicated mechanically, which can raise the cost of even the simplest models.
Some espresso machines employ steam pressure instead of a pump for brewing espresso. The downside is that the boiler that produces steam also raises the temperature of water to boiling, which can lead to over-extraction. These machines also have to continually rebuild their pressure between cups. This takes energy and time.
Many espresso machines use an rotary or a vibration pump. A vibration model uses the vibrating disk to create pressure, while the rotary model pushes hot water through the ground at a fast speed. Both types of machines can produce an excellent espresso, but rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is the part that heats water to the optimal temperature for extraction. The steam that is produced will eventually reach the portafilter, which contains the espresso coffee grounds. The steam is then channeled into the cup. During this process, steam causes pressure to push through the grounds of the coffee. This creates a layer crema that is then poured over. This is one of the main characteristics of a good espresso.
There are three types of espresso machines, each having different pumps and brew temperature. There are many ways to control the brew as well as the size of cup that can be produced by the machine.
The first espresso machines were steam-type. They employed one boiler to create steam and brew, however, the pressure they could generate was low – only two bars of atmospheric pressure maximum. This led to the coffee tasting bitter and burnt. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used barista espresso machine maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they imagine these machines. With a semi-automatic espresso coffee machine for home machine, you have to grind the beans and tamp them yourself but the pump regulates the flow of water and pressure. This is a great compromise between the human touch and mechanized quality.
The Filter
Espresso machines usually use filters that separate the coffee grounds from the hot water. The filter is also a crucial part of the temperature control system, as it prevents the machine from overheating.
It also aids in flavor as a filter can allow for a longer bloom time. This allows the beans to release their nuances and gives an opportunity to improve extraction.
However, it is important to keep in mind that even a good filter can result in a poor cup of coffee, as the quality of the beans and extraction is still crucial.
This is where the magic happens. It’s what makes espresso machines home taste great. The grouphead (also called the brewhead) is where you put the portafilter – the thingy that you put the grounds of your coffee into when making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. This is then pushed through the grounds with high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pumps-driven models. They are however limited in their ability to create the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They use an air-compressor to push hot water across the ground. They are also more mobile than electric steam-driven espresso machines.