A Look At The Ugly Truth About Machine Espresso
A Look At The Ugly Truth About Machine Espresso
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How Does Machine Espresso Work?
The machine espresso utilizes precision pressure, and a filter technology that is mind-blowing to make the coffee you love. But how exactly does it work?
Espresso is produced by pushing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.
The Group Head
As the name suggests the group head is the place you place your portafilter when brewing espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the resulting extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are focused on temperature stability, some on pre-infusion features, and others are designed to control the lever. There are some that contain a variety of features, like the E61, which is considered the classic choice among many baristas due to its ability to offer multiple benefits in one package.
As you can see in the above image the group head is made up of many notches in which you can put your portafilter, then twist it by hand to lock it in. There is also a gasket made of rubber in the notches, which helps create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for a precise location of the portafilter which is vital to ensure a consistent extraction.
The group head not only allows you to place your portafilter easily however it also keeps the same temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is at the right level for extraction. It is important to realize that even a slight difference can make the difference between a great and a great espresso.
The Pump
The motorized pumps used in rotary espresso machines provide the nine atmospheric bar pressure needed for espresso extraction. This differs from manual piston machines that rely on a lever. This pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.
Pumps are typically less expensive than piston-driven machines, and they tend to last longer, although both types of machine can degrade with overuse and insufficient cleaning. They also make mechanically complex which can result in the cost of even the simplest models.
Some espresso machines use steam pressure instead of a pump in order to brew espresso. This could lead to over-extraction since the boiler that produces steam also heats the water to boil. The machines must also constantly rebuild their pressure in between cups. This requires energy and time.
Many espresso machines make use of either a rotary or vibration pump, which has a vibration model using a vibrating disc to create pressure and a rotary model pushing hot water through the grounds at high speed. Both models can make a great espresso, but the rotary models are quieter and more durable than vibration pumps.
The Boiler
The boiler makes the water warm to the perfect temperature for extraction. The steam that is produced reaches the portafilter that contains the ground espresso and is then funneled down into the cup. During this process, the steam causes pressure to push through the grounds of the coffee. 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, which differ in the type of pump they use and the degree of heat that the espresso is. There are a variety of ways to control the brew as well as the size of cup that can be produced by the machine.
The first espresso machines were steam-types. They had only one boiler to make steam and brew, however the pressure they were coffee and espresso maker able to generate was low - only two bars of atmospheric pressure, at most. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most common espresso maker is a semi-automatic machine with an electric pump. These are the things people think of when they think of an espresso machine. If you have a semi-automatic machine you have to grind the beans and tamp them yourself but the pump is able to regulate the flow of water and pressure. This is a perfect compromise between human control and mechanized reliability.
The Filter
Espresso machines usually have a filter that separates the grounds of the coffee from hot water. The filter is also a vital element of the temperature control system since it helps prevent the machine from overheating.
It also aids in flavor, as it lets you enjoy a longer bloom time. This allows the beans to release their flavors, and allows for better extraction.
It is important to keep in mind that even the best filter can make a bad cup of coffee. The quality of the beans, as well as the extraction, remain crucial.
It's in this area that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead (also called the brewhead) is where you put the portafilter - the thingy used to place the grounds of your coffee into when making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These types of machines are usually less expensive and simpler to maintain than pump-driven models. However, they are limited in their ability to provide the ideal conditions for brewing since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent years, compressed air-driven espresso machines have become more popular. They utilize an air compressor to force hot water through the ground and are much more mobile than steam-driven electric espresso machines.