How Does Machine Espresso Work?
Machine espresso employs precise pressure and incredible filter technology to produce the delicious coffee we enjoy. How exactly does it work?
To make an 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 Head of the Group
As the name implies, the group head is the place you place your portafilter while making espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are many different kinds of group head each with its particular advantages and drawbacks. Some are designed to provide temperature stability while others are designed to handle pre-infusion. Others are built to control the lever. There are also some that include a mix of features, such as the E61, which is the most popular choice among baristas due to its capacity to offer multiple benefits in a single package.
As you can see from the picture above the head of the group is fitted with several notches. The portafilter is placed in these notches, then turn the head around to secure it. A gasket made of rubber is placed in the notches to create a seal when you insert your portafilter. The notches on the head allow for a precise location of the portafilter which is vital for a consistent extraction.
The group head is not just able to allow you to place your portafilter easily, but it also maintains the same temperature. It does this by circulating hot water through the brew basket and around the portafilter to ensure that it's always at the right temperature for extraction. look here is important to note that even a small difference can make the difference between a decent and a great espresso.
The Pump
The motorized pumps used in espresso machines rotary provide nine atmospheric bars of pressure required to extract espresso. This is different from manual piston machines that rely on levers. The pressure builds by removing tap water from a reservoir, and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.
Pumps tend to be cheaper than piston-driven machines, and they tend to last longer. However, both types of machines may become damaged due to excessive use and poor cleaning. They also create mechanical complexity, which can result in a high price tag on even the most basic models.
Certain espresso machines eliminate the pump completely and use steam pressure to brew espresso. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. These machines also have to constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines make use of an rotary or vibrating pump, with a vibrating model that uses a vibrating disc that generates the pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines can make great espresso, but rotary machines are more stable, quieter and less likely to fail.
The Boiler
The boiler is the element that heats water to an optimal temperature for extraction. The steam produced reaches the portafilter, which is the container that holds the espresso coffee grounds. It is then poured into the cup. During this process, steam creates pressure and pushes through the coffee grounds. This results in a whipped-up top of the espresso. This is one of the hallmarks of a great espresso.
There are three distinct types of espresso machines, each with different pumps and brew temperature. There are a variety of ways to control the brew and the size of cup that can be produced by the machine.
The first espresso machines were steam-type. They had one boiler to make both brew and steam, however the pressure they were able to generate was low - only two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso machine is a semiautomatic that has an electric pump. These are the images people have when they imagine an espresso machine. With a semi-automatic machine, you grind the beans and then tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is an excellent combination of human control and mechanized accuracy.
The Filter
Espresso machines usually use filters that separate the grounds of the coffee from hot water. The filter is also an essential element of the machine's temperature control, as it prevents overheating.
It also aids in flavor, as a filter lets you enjoy a longer bloom phase. This allows beans to let their nuances out and provides the chance 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, remain vital.
It's here that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, sometimes called the brewhead, is where the portafilter (the thing you put the ground coffee into) is placed when you're making espresso.
Steam-driven espresso machines make use of hot water that is heated inside an airtight vessel to create steam. The steam then moves hot water through the grounds of coffee under high pressure. These kinds of machines are typically less expensive and simpler to maintain than pump-driven models. However, they are not as efficient in their capacity to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.
In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to push hot water through grounds and are significantly more portable than steam-driven electric machines.