It's The Ugly Truth About Machine Espresso
It's The Ugly Truth About Machine Espresso
Blog Article
How Does Machine Espresso Work?
The machine espresso uses precise pressure and filtering technology that is amazing to create the coffee you enjoy. But how exactly does it work?
Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.
The Group Head
As the name implies the group head is the place you place your portafilter when making espresso. It distributes water into the portafilter, and then controls the pressure of the extraction. There are many different kinds of group heads, each with their own advantages and disadvantages. Some are specifically designed for the stability of temperature while some are specifically designed to handle pre-infusion. Some are designed to control the lever. Some include a combination like the E61. This is a popular choice among baristas as it provides a variety of advantages in one package.
As you can see in the image above the group head comes with several notches to put your portafilter, then twist it by hand to secure it. A gasket of rubber is situated within the notches to create a seal when you insert your portafilter. The notches on the head permit a precise location of the portafilter which is crucial to ensure an efficient extraction.
The group head is not just able to allow the portafilter to be inserted easily but also maintains a constant temperature. It does this by cycling hot water through the brew container and around the portafilter, making sure that it is always at the right temperature for extraction. It is important to remember that even a tiny deviation can make the difference between a great and a excellent espresso.
The Pump
Unlike manual piston machines, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps to deliver the nine atmospheric bars of pressure necessary 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 in the group head.
Pumps are generally less expensive than piston-driven machines, and they tend to last longer, but both types of machines could get damaged through overuse and lack of cleaning. Pumps are also more complex mechanically, which can raise the cost of even simplest models.
Some espresso machines eliminate the pump completely and instead employ steam pressure to create espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of the water until it reaches boiling, which can lead to excessive extraction. In addition these machines are often required to rebuild their pressure between cups, which requires time and energy.
Many espresso machines employ a vibration or rotary pump, which is a vibration model that uses a vibrating disc to create pressure, and a rotary model pushing hot water through the grounds at high speed. Both types of machines can make a great espresso, however the rotary models are quieter and more durable than vibration pumps.
The Boiler
The boiler will heat the water to the perfect temperature for extraction. The resultant steam then reaches the portafilter which holds the ground espresso coffee and gets funnelled down into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This creates a crema on top of the espresso. This is one of the hallmarks of a great espresso.
There are three types of espresso makers, which differ in the kind of pump they use and the degree of heat that the coffee is. There are different ways to control the brew as well as the size of the cup that can be made by the machine.
The first espresso machines were steam-based. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso machine is a semiautomatic with an electric pump. These are the things people think of when they imagine an espresso machine. With a semi-automatic machine you grind the beans and tamp them by hand, but the pump controls the flow of water and pressure. This is an excellent combination of human control and mechanized reliability.
The Filter
Typically, espresso machines have filters that separate the coffee grounds as they pass through the hot water. The filter is also a vital component of the machine's temp control, as it helps prevent overheating.
A filter also improves flavor as it allows for a longer flowering phase. This lets the beans release their nuances, and also allows for better extraction.
However, it is important to keep in mind that even a good filter could result in a bad cup of coffee, because the quality of the beans and extraction is vital.
This is where the magic happens, it's what makes an espresso really taste great. The grouphead (also known as the brewhead) is where you espresso coffee machine place the portafilter, the device which you put the coffee grounds into, when making espresso.
In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam. Steam then pushes the hot water through the grounds with high pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the ideal brewing conditions, since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent years, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water into the ground and are more mobile than electric steam-driven espresso machines.