5 Killer Quora Questions On Machine Espresso
5 Killer Quora Questions On Machine Espresso
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How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to create the coffee we love. What exactly is it?
Espresso is made by pushing hot water 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 that you put in when making espresso. It distributes water into the portafilter, and regulates the pressure during the extraction. There are many different types of group heads each with its own advantages and drawbacks. Some are designed for stability of temperature while others are specifically designed to handle pre-infusion. Others are built to control the lever. Some are a combination, like the E61. This is a popular choice among baristas due to the fact that it has multiple advantages in one package.
As you can see in the image above the group head is fitted with several notches. It is possible to place your portafilter in these notches, then twist the head to secure it. A gasket made of rubber is placed inside the notches, which helps create a seal as you insert your portafilter. The notches on the head allow for an exact positioning of the portafilter which is vital for an efficient extraction.
In addition to allowing you easily place your portafilter in, the group head is responsible to maintain an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket, ensuring the temperature is always right to extract the coffee. It is important to remember that even a small variation can mean the difference between a great and a excellent espresso.
The Pump
The motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure that is required for espresso extraction. This differs from manually operated piston machines that employ levers. The pressure builds by drawing tap water from a reservoir, and pumping it through a heat exchanger before being shot through the ground coffee in the group head.
Pumps tend to be cheaper than piston-driven models, and they tend to last longer, although both types of machines can be damaged by excessive use and inadequate cleaning. They also create mechanical complexity and can lead to an expensive price for even the simplest models.
Some espresso machines employ steam pressure instead of a pump for brewing espresso. This can result in over-extraction because the boiler that produces steam also causes the water to boil. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.
A majority of espresso machines utilize the rotary or vibration pump. A vibration model employs an oscillating disk to create pressure, while the circular model pushes hot liquid through the ground at a rapid speed. Both models are capable of producing excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
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, which contains the ground espresso coffee and is then pumped down into the cup. In this process, the steam creates pressure that pushes through the grounds of the coffee. This results in a layer of crema on top. This is a hallmark of a great espresso.
There are three distinct types of espresso machines, each with different types of pumps and brew temperature. There are different ways that the brew can be controlled, as well as the size of the cup the machine is capable of making.
The first espresso machines were steam-type. The first espresso machines were steam types. This led to the coffee tasting burnt and bitter. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most common espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp the beans yourself however the pump controls the water flow and pressure. This is an excellent compromise between human touch and the mechanized quality.
The Filter
Espresso machines usually have filters that separate the coffee retro espresso machine grounds from the hot water. The filter is also a crucial element of the temperature control system as it keeps the machine from overheating.
Filters also aid in flavor since it allows for an extended flowering time. This lets the beans let their nuances out, and allows for a better extraction.
It is important to remember that even the most efficient filter can result in a bad cup of coffee. The quality of the beans and the extraction process, are still very important.
It's here that the magic occurs. This is what makes espresso taste so delicious. The grouphead, sometimes referred to as the brew head, is where the portafilter (the thing you put the ground coffee in) is placed when you're making espresso.
In the steam-driven espresso machine hot water is heated in an airtight container to create steam, which is then pushed through the grounds under high pressure. These kinds of machines are typically less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, since they are only operating at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.
In recent times, espresso machines powered by a compressed air pump have become increasingly popular. They use an air compressor to force the hot water through the grounds and are much more portable than electric steam-driven machines.