How Does Machine Espresso Work?
The machine espresso is made using precise pressure, as well as a filtering technology that is amazing to create the coffee you love. But how exactly does it work?
Espresso is made by forcing hot water at high pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.
The Head of the Group
The group head is the portafilter that you insert when brewing espresso. It disperses water in the portafilter, and controls the pressure of the extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some are designed to provide temperature stability while others are designed to handle pre-infusion. Others are made to control the lever. Some have a combination, such as the E61. This is a preferred choice for baristas due to the fact that it has multiple advantages in a single package.
As you can see from the above photo the head of the group is fitted with several notches. You place your portafilter into these notches and twist the head to secure it. A gasket made of rubber is positioned inside the notches, which helps create a seal when you insert your portafilter. The notches on the head allow for an exact positioning of the portafilter which is crucial for an efficient extraction.
In addition to allowing you to effortlessly insert your portafilter the group head is responsible to maintain an even temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is at the right level for extraction. It is important to note that even a few degree deviation can make the difference between a great and a excellent espresso.
The Pump
Contrary to manual piston machines which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure required for espresso extraction. This pressure is built up by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally less expensive and last longer than piston-driven machines. However, both kinds of machines can degrade because of frequent use and insufficient cleaning. They also increase the complexity of mechanical systems, which can result in the cost of even the simplest models.
Some espresso machines employ steam pressure instead of a pump for brewing espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of water until it reaches boiling which can cause over-extraction. Additionally these machines are often required to rebuild their pressure between cups, which requires time and energy.
Many espresso machines utilize either a rotary or vibration pump, with a vibration model using a vibrating disc to generate the pressure and rotating models that push hot water through the grounds under high speed. Both machines produce great espresso but rotary machines are quieter, more durable and less likely to break.
The Boiler
The boiler is the component that heats water to an optimal temperature to extract. The steam created reaches the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. In this process, the steam creates pressure that pushes through the grounds of the coffee. This produces a layer of crema on top. This is a sign of a good espresso.
There are three types of espresso makers. They differ in the kind of pump they use and how hot the espresso is. There are also different ways that the brew may be controlled as well as the size of the cup the machine is capable of making.
The earliest espresso machines were steam types. The earliest espresso machines were steam types. The coffee tasted bitter and burned. This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most commonly used espresso machine is a semiautomatic that has an electric pump. This is what people envision when they think of an espresso machine. With a semi-automatic machine, you have to grind the beans and tamp them by hand, but the pump provides regulated water flow and pressure. This is a perfect compromise between human control and mechanised reliability.
The Filter
Espresso machines typically have a filter that separates the grounds of the coffee from hot water. The filter is also a vital element of the machine's temperature control, as it prevents overheating.
A filter also helps with flavor, as it permits an extended flowering time. This helps the beans to release their nuances and gives an opportunity for better extraction.
barista espresso coffee machine is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction process, remain vital.
It's in this area that the magic occurs. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is the place where the portafilter (the container you place the coffee ground into) is placed when you're making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank to produce steam, which then pushes the hot water through the grounds at a high pressure. These machines are less expensive and easier for the user to maintain than pumps-driven models. They are however limited in their ability for creating the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed-air-pump-driven espresso machines have become more popular. They utilize an air compressor to push hot water into the grounds and are significantly more portable than electric steam-driven machines.