The Most Sour Advice We've Ever Heard About Machine Espresso
The Most Sour Advice We've Ever Heard About Machine Espresso
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How Does Machine Espresso Work?
The machine espresso makes use of precise pressure, as well as a filtering system that is awe-inspiring to make the coffee you love. How exactly does it work?
Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee. However, the pressure is the major difference.
The Head of the Group
The name implies, the group head is where you put your portafilter in when brewing espresso. It is responsible for dispersing water into the portafilter before controlling the pressure that results from the extraction. There are a variety of group heads each with its own advantages and disadvantages. Some are designed for the stability of temperature while some are specifically designed to handle pre-infusion. Others are built to control the lever. Some include a combination like the E61. This is a preferred choice for baristas as it provides a variety of advantages in one package.
As you can see in the image above, the group head has numerous notches that you can place your portafilter before twisting it by hand to lock it in. A rubber gasket is located in the notches to create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is crucial for an accurate extraction.
In addition to allowing you to easily place your portafilter in, the group head is also responsible for maintaining a consistent temperature. This is achieved by cycling hot water around the portafilter and through the brew-basket, making sure the temperature is always right to extract the coffee. This is vital, because just a few degrees could make the difference between good and great espresso.
The Pump
The motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure that is required to extract espresso. This differs from manually operated piston machines that employ a lever. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pumped through the ground coffee inside the group head.
Pumps tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines can degrade due to overuse and insufficient cleaning. Pumps are also more complicated mechanically, which could increase prices of even most basic models.
Some espresso machines remove the pump entirely and use steam pressure to brew espresso. The disadvantage of this is that the same boiler that produces steam also increases the temperature of water to the point of boiling which can cause over-extraction. Additionally the machines often have to restore their pressure between cups, which takes time and energy.
A majority of espresso machines utilize either a vibration or rotary pump. A vibration model uses an oscillating disk to create pressure, while a rotating model pushes hot water through the ground at a rapid speed. Both machines produce great espresso, however rotary machines are quieter, more durable and less likely to fail.
The Boiler
The boiler is the one that will heat the water to the perfect temperature to extract. The steam that is produced reaches the portafilter that contains ground espresso beans and gets funnelled down into the cup. During this process, steam creates pressure to push through the coffee grounds. This creates a foam on the top of the espresso. This is a sign of a great espresso.
There are three kinds of espresso machines, each with different pumps and the temperature of the brew. There are various ways to control the strength of the brew and the size of the cup that can be made by the machine.
The earliest espresso machines were steam types. They used one boiler to create both steam and brew but the pressure they could produce was very low - just two bars of atmospheric pressure at the most. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most well-known espresso machine is a semiautomatic with an electric pump. These are the things people think of when they think of an espresso machine. With a semi-automatic machine you need to grind the beans and tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is a great compromise between human control and mechanized consistency.
The Filter
Espresso machines usually use a filter that separates the grounds of the coffee from hot water. The filter is also a vital element of the machine's temperature control, since it helps to prevent overheating.
It also enhances flavor as a filter allows for a longer bloom time. This helps the beans to let their nuances out and provides an opportunity for a better extraction.
However, it is important to remember that even a high-quality filter can make a terrible cup of coffee, since the quality of the beans and extraction is still important.
This is where the magic happens, and it's what makes espresso taste great. The grouphead (also called the brewhead) is where you put the portafilter - the thingy which you put the coffee grounds in, when making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. Steam is then pushed through the grounds at a high pressure. These kinds of machines are typically less expensive and easier to maintain than pump-driven models. They are however limited in their ability for creating the ideal conditions for brewing since they only operate with click here 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, espresso machines driven by a compressed air pump have become increasingly popular. They use an air-compressor to force hot water through the ground and are more mobile than electric steam-driven espresso machines.