How Does Machine Espresso Work?
The machine espresso utilizes precision pressure, and a filter technology that is awe-inspiring to make the coffee you enjoy. How exactly does it work?
To make an espresso hot water is pushed 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
The group head is the portafilter is inserted when you are making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are designed for temperature stability while others are specifically designed to handle pre-infusion. Some are designed to control the lever. Some are a combination, like the E61. This is a popular choice among baristas since it provides multiple advantages in a single package.
As you can see in the image above The group head features many notches in which you can put your portafilter, then twist it manually to secure it. There is also a gasket made of rubber in the notches, which helps create an airtight seal when you insert your portafilter into the machine. espresso machines uk on the head allow for an exact position of the portafilter which is essential to ensure an efficient extraction.
The group head is not just able to allow the portafilter to be inserted easily but also maintains the temperature at a constant level. This is done by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is at the right level to extract the coffee. This is crucial, since even a small difference in temperature can make the difference between excellent and great espresso.
The Pump
The motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure that is required for espresso extraction. This differs from manual piston machines that rely on levers. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior to 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 could degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, and can add to the cost of even the simplest models.
Some espresso machines make use of steam pressure instead of a pump for brewing espresso. This could lead to over-extraction since the boiler that produces steam also causes the water to boil. The machines must also continuously rebuild their pressure between cups. This requires energy and time.
A large majority of espresso machines employ the rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, while the rotary model pushes hot water through the ground at a rapid speed. Both machines can produce excellent espresso but rotary machines are quieter, more durable and less likely to break.
The Boiler
The boiler is the component which heats the water to the optimal temperature for extraction. The resulting steam is then transferred to the portafilter which holds ground espresso beans and gets funnelled down into the cup. The steam generates enough pressure to push the grounds of coffee through. This creates a layer crema on top. This is a sign of a great espresso.
There are three kinds of espresso makers, which differ in the type of pump they employ and how hot the brew is. There are different ways to control the amount of brew, as well as the size of the cup that can be made by the machine.
The first espresso machines were steam-based. They used a single boiler to make steam and brew, but the pressure they could create was minimal - two bars of atmospheric pressure at most. This led to the coffee tasting bitter and burnt. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most popular espresso maker is a semiautomatic machine with an electric pump. These are what people imagine when they think of an espresso maker. With a semi-automatic machine you need to grind the beans and tamp them by hand. However, the pump provides regulated water flow and pressure. This is an excellent combination of human control and mechanized reliability.
The Filter
Typically, espresso machines employ a filter to separate out the grounds of coffee when they pass through the hot water. The filter is also a vital component of the temperature control system because it stops the machine from overheating.
It also enhances flavor, as it can allow for a longer bloom time. This allows the beans to release their flavors, and allows for better extraction.
However, it is important to keep in mind that even a top filter could result in a bad cup of coffee, as the quality of the beans and extraction are important.
It's here that the magic occurs. This is the reason why espresso tastes so good. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the thingy you put the ground coffee in) is placed when you're making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight container to produce steam. The steam then moves hot water through the grounds of coffee at high pressure. These machines are cheaper and easier for the owner to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing, as they operate with 1-1.5 bar of pressure. 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 push the hot water through the grounds and are much more portable than electric steam-driven machines.