How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly is it that makes it work?
In order to make espresso hot water is pushed under pressure through finely ground coffee. The process is similar to that of making drip coffee. However, it is the pressure that makes the main difference.
The Group Head
The group head is the portafilter you put in when making espresso. It disperses water in the portafilter and regulates the pressure of the extraction. There are many different types of group heads each with its own advantages and drawbacks. Some are focused on temperature stability, some on pre-infusion options, and others are designed to control the lever. Some are a combination, like the E61. This is a preferred choice for baristas since it provides multiple advantages in a single package.
As you can see in the image above the group head comes with numerous notches that you can place your portafilter and then twist it with your hands to secure it. A gasket made of rubber is placed inside the notches, which helps create a seal when you insert your portafilter. The notches allow for the precise placement of the portafilter. This is crucial for an accurate extraction.
The group head is not just able to allow you to insert your portafilter easily however, it also keeps an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket to ensure that the temperature is always at the right level for extraction. It is crucial to keep in mind that even a few degree difference can make the difference between a decent and a great espresso.
The Pump
The motorized pumps that are used in rotary espresso machines supply the nine atmospheric bar pressure required to extract espresso. This is different from manual piston machines that rely on a lever. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior being shot through the ground coffee inside the group head.
Pumps tend to be less expensive than piston-driven machines, and they tend to last longer, although both types of machines can be damaged by excessive use and inadequate cleaning. Pumps are also more complex mechanically, which can raise prices of even simple models.
Some espresso machines remove the pump completely and instead employ steam pressure to create espresso. This can lead to over-extraction as the boiler that produces steam also heats the water to boil. They also have to constantly rebuild their pressure in between cups. This takes energy and time.
A large majority of espresso machines employ either a vibration or rotary pump. A vibration model utilizes an oscillating disk to create pressure, while the rotating model pushes hot water through the ground at a high speed. Both machines produce great espresso but rotary machines are more quiet, durable and less likely to break down.
The Boiler
The boiler is what is used to heat the water to the perfect temperature to extract. The resultant steam then reaches the portafilter, which contains the ground espresso and is then funneled down into the cup. The steam creates pressure that pushes through the coffee grounds. This produces a layer of crema on top. This is one of the main characteristics of a great espresso.
There are three kinds of espresso machines, each with different pumps and brew temperature. There are various ways to control the amount of brew, as well as the size of cup that can be made by the machine.
The earliest espresso machines were steam-based. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. here This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most popular espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they imagine these machines. Semi-automatic machines require you to grind and tamp the beans on your own, but the pump regulates the water flow and pressure. This is a fantastic combination of human control and mechanised consistency.
The Filter
Espresso machines typically have filters that separate the grounds of the coffee from the hot water. The filter is also an essential element of the machine's temperature control, as it helps prevent overheating.
It also enhances flavor, as it allows for a longer bloom time. This allows the beans to release their flavor and also allows for better extraction.
However, it is important to remember that even a top filter can make a terrible cup of coffee, because the quality of the beans and extraction is important.
This is where the magic happens, it's the thing that makes espresso taste great. The grouphead, sometimes referred to as the brewhead, is where the portafilter (the device you put the coffee ground into) sits when you're making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to make steam. The steam then pushes hot water through the grounds of coffee at high pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They utilize an air compressor to push the hot water through the grounds and are more portable than steam-driven electric machines.