The 10 Worst Machine Espresso Failures Of All Time Could Have Been Prevented
The 10 Worst Machine Espresso Failures Of All Time Could Have Been Prevented
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How Does Machine Espresso Work?
The machine espresso is made using precision pressure, and a filter technology that is awe-inspiring to create the coffee you love. How does it work exactly?
In order to make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.
The Head of the Group
The name implies, the group head is where you insert your portafilter when making espresso. It disperses the water into the portafilter and controls the pressure of the extraction. There are numerous kinds of group heads each with distinct advantages and drawbacks. Some are focused on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. Some come with a combination of both, like the E61. This is a very popular choice for baristas because it offers multiple benefits in a single package.
As you can see in the image above, the group head has a number of notches. It is possible to place your portafilter inside these notches, and then twist the head to lock it. A gasket of rubber is situated within the notches to create a seal when you insert your portafilter. The notches allow for the precise placement of the portafilter. This is crucial for an even extraction.
The group head is not just able to allow you to insert your portafilter easily but also maintains the temperature at a constant level. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it's always at the right temperature to extract. It is important to remember that even a tiny deviation can make the difference between a good and great espresso.
The Pump
The motorized pumps used in espresso machines that rotate provide the nine atmospheric bar pressure needed to extract espresso. This differs from manual piston machines that rely on levers. The pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before it is shot through the ground coffee in the group head.
Pumps are generally less expensive than piston-driven machines and tend to last longer. However, both types of machines may be damaged by excessive use and inadequate cleaning. They also make mechanically complex that can lead to an expensive price for even the simplest models.
Certain espresso machines can eliminate the pump completely and employ steam pressure to create espresso. The disadvantage of this is that the same boiler that produces steam also raises the temperature of water to the point of boiling and can result in over-extraction. They also have to constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines use a rotary or vibration pump. A vibration model utilizes the vibrating disk to create pressure, while a rotating model pushes hot water through the ground at high speed. Both types of machines can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps.
The Boiler
The boiler will heat the water to the right temperature for extraction. The steam created gets to the portafilter which is the container that holds the espresso coffee grounds. It is then funneled into the cup. The steam is able to create enough pressure to push the grounds of the coffee through. This creates a crema on top of the espresso. This is a hallmark of a good espresso.
There are three types of espresso makers, and they differ in the kind of pump they use and how hot the espresso 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-type. They had only one boiler to make both steam and brew, but the pressure they could produce was not very high - two bars of atmospheric pressure maximum. This led to the coffee tasting bitter and burnt. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso machine is a semiautomatic with an electric pump. These are the images people have when they think of an espresso machine. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the flow of water and pressure. This is a great combination of human control and mechanized accuracy.
The Filter
Espresso machines typically have filters that separate the grounds of the coffee from the hot water. The filter is also a vital element of the temperature control system as it keeps the machine from overheating.
A filter also helps with flavor, as it permits a longer flowering phase. This lets the beans release their flavors, and allows for a better extraction.
It is important to remember that even the finest filter can make a bad cup of coffee. The quality of the beans, and the extraction process, remain vital.
This is where the magic happens, and it's what 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.
In the steam-driven espresso machine hot water is heated in an airtight container to produce steam, which is then pushed through the grounds with high pressure. These machines are less expensive and easier to maintain than pumps-driven models. They are however limited in their ability to create the perfect conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, compressed air pump-driven espresso here machines have become more popular. They utilize an air compressor to force hot water through grounds and are more portable than electric steam-driven machines.