How Does
Machine Espresso Work?
Machine espresso utilizes precise pressure and mind-blowing filter technology to create the coffee we love. What exactly is it that makes it work?
To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.
The Group Head
The group head is the portafilter that you put in when making
professional espresso machine. It disperses water in the portafilter and regulates the pressure of extraction. There are a variety of group heads each with their own advantages and disadvantages. Some are focused on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some include a combination like the E61. This is a preferred choice for baristas as it provides a variety of advantages in one package.
As you can see in the picture above the head of the group is fitted with a variety of notches. You can place your portafilter into these notches and turn the head around to secure it. A gasket of rubber is situated inside the notches, which helps create a seal as you insert your portafilter. The notches on the head permit a precise location of the portafilter which is necessary for an even extraction.
The group head not only lets you to put in your portafilter easily however, it also keeps an even temperature. This is done by cycling hot water around the portafilter,
Machine Espresso 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 tiny difference can make the difference between a great and a excellent espresso.
The Pump
In contrast to manual piston machines which rely on 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 built by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be cheaper than piston-driven models, and they tend to last longer, however both types of machine can be damaged by excessive use and
Machine espresso inadequate cleaning. Pumps are also more complicated mechanically, and can add to the cost of even the most basic models.
Some espresso machines remove the pump entirely and employ steam pressure to create espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of water to the point of boiling and can result in excessive extraction. Additionally the machines often have to restore their pressure between cups, which requires time and energy.
A majority of espresso machines use the rotary or vibration pump, with a vibration model that uses a vibrating disc to create the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to fail.
The Boiler
The boiler is the component which heats the water to the ideal temperature to extract. The resultant steam then reaches the portafilter which holds ground espresso beans and is then pumped into the cup. During this process the steam creates enough pressure to push the grounds of coffee through. This creates a crema on the top of the espresso. This is one of the main characteristics of a good espresso.
There are three kinds of espresso makers, which differ in the type of pump they employ and the degree of heat that the brew is. There are many ways to control the brew and the size of the cup that can be made by the machine.
The first espresso machines were steam types. The earliest espresso machines were steam types. The coffee tasted bitter and burned. The modern espresso machine was designed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most common
retro espresso machine maker is a semi-automatic machine that has an electric pump. This is what people envision when they think of an espresso machine. Semi-automatic machines require you to grind and tamp your beans yourself however the pump controls the flow of water and pressure. This is an excellent compromise between human touch and mechanized accuracy.
The Filter
Espresso machines usually have a filter that separates the coffee grounds from the hot water. The filter is also an essential component of the temperature control system, as it prevents the machine from overheating.
It also helps with flavor, as a filter can allow for a longer bloom time. This allows the beans to let their nuances out, and also allows for better extraction.
It is important to keep in mind that even the best filter could result in a poor cup of coffee. The quality of the beans and the extraction process remain vital.
This is where the magic happens, it's the thing that makes an espresso really taste great. The grouphead, sometimes called the brew head, is the place where the portafilter (the container you place the ground coffee into) sits 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 under high pressure. These machines are cheaper and easier to maintain than pumps-driven models. They are however limited 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 years, compressed air-driven espresso machines have become more popular. They use an air compressor to force hot water through the ground and are much more mobile than electric steam-driven espresso machines.