10 Meetups About Machine Espresso You Should Attend
How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to make the delicious coffee we enjoy. How exactly does it work?
Espresso is made by forcing hot water under pressure through finely ground coffee. The process is similar to making drip coffee but the key difference is in the pressure.
The Group Head
As the name suggests the group head is the place you put your portafilter in when making espresso. It disperses water in the portafilter, and then regulates the pressure of extraction. There are a variety of types of group heads each with its own advantages and disadvantages. Some focus on temperature stability, while others on pre-infusion capabilities, and still others are designed to control the lever. Some come with a combination of both, such as the E61. This is a popular choice among baristas because it offers multiple benefits in one package.
As you can see from the image above, the group head has a number of notches. It is possible to place your portafilter in these notches and then twist the head to lock it. A rubber gasket is located within the notches to make a seal when you insert your portafilter. The notches on the head allow for a precise location of the portafilter which is vital to ensure an even extraction.
Aside from allowing you to effortlessly insert your portafilter the group head is also responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter and through the brew-basket, making sure the temperature is always right for extraction. This is vital, because even a small difference in temperature can make the difference between a excellent and great espresso.
The Pump
In contrast to piston machines that are manually operated, which use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to supply the nine atmospheric bars of pressure that are required for espresso extraction. The pressure builds by removing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.
Pumps are typically cheaper and last longer than piston-driven machines. However, both types of machines can degrade because of excessive use and insufficient cleaning. Pumps are also more complicated mechanically, which can raise the cost of even simple models.
Some espresso machines make use of steam pressure instead of a pump to make espresso. This can cause over-extraction because the boiler that produces steam also warms the water to boil. They also have to continuously rebuild their pressure between cups. This requires energy and time.
Many espresso machines make use of a rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, while a Rotary model pushes hot coffee through the ground at a high speed. Both types of machines are capable of producing excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler is what makes the water warm to a temperature that is ideal to extract. The steam that is produced reaches the portafilter which holds ground espresso beans and is then pumped into the cup. The steam is able to create enough pressure to push the coffee grounds through. This produces a layer of crema on top. This is one of the main characteristics of a good espresso.
There are three kinds of espresso makers. They differ in the kind of pump they use and the degree of heat that the coffee is. There are various ways to control the brew and the size of cup that can be made by the machine.
The first espresso machines were steam-types. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burned. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso maker is a semi-automatic one with an electric pump. This is what people envision when they think of an espresso machine. If you have a semi-automatic machine you must grind the beans and tamp them by hand. The pump is able to regulate the flow of water and pressure. This is an excellent combination of human control and mechanised consistency.
espresso coffee machines have filters that separate the grounds of coffee from hot water. The filter is also an essential part of the machine's temperature control, since it helps to prevent overheating.
A filter also improves flavor since it allows for a longer flowering phase. This allows the beans to let their nuances out, and improves extraction.
However it is crucial to keep in mind that even a high-quality filter can result in a poor cup of coffee, since the quality of the beans and extraction are important.
This is where the magic happens, it's what makes an espresso really taste great. The grouphead, also called the brewhead, is where the portafilter (the device you put the coffee grounds into) is placed when you're making espresso.
In the steam-driven espresso machine hot water is heated in an airtight tank to create steam, which is then pushed through the grounds at high pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent years, compressed-air-pump-driven espresso machines have become more popular. They utilize an air compressor to force hot water through the grounds, and are far more portable than steam-driven electric machines.