13 Things About Machine Espresso You May Not Have Considered
How Does Machine Espresso Work?
Machine espresso uses precision pressure and incredible filter technology to produce the perfect cup of coffee. How exactly does dual boiler espresso machine work?
Espresso is made by forcing hot water at high pressure through finely-ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference.
The Head of the Group
As the name suggests the group head is the place you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the resulting extraction. There are a variety of group heads, each with its own advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some come with a combination of both, like the E61. This is a favorite among baristas since it provides multiple benefits in one package.
As you can see from the picture above the group head is fitted with a variety of notches. You can place your portafilter into these notches and twist the head to lock it. A gasket made of rubber is positioned in the notches to make a seal when you insert your portafilter. The notches on the head permit an exact location of the portafilter which is crucial to ensure a consistent extraction.
The group head does not just allow you to put in your portafilter easily however, it also keeps a constant temperature. It does this by cycling hot water through the brew container and around the portafilter, ensuring that it's always at the correct temperature to extract. It is crucial to keep in mind that even a tiny difference can make the difference between a good and great espresso.
The Pump
The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bars of pressure required for espresso extraction. This differs from manual piston machines that use a lever. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally less expensive and last longer than piston-driven machines. However, both kinds of machines can deteriorate because of frequent use and poor cleaning. They also create mechanical complexity, which can result in a high price tag on even the simplest models.
Certain espresso machines remove the pump completely and employ steam pressure to create espresso. The drawback is that the boiler that produces steam also raises the temperature of the water to the point of boiling, which can lead to excessive extraction. In addition these machines are often required to rebuild their pressure between cups, which requires time and energy.
A majority of espresso machines use either a rotary or vibration pump, with a vibrating model using a rotating disc to create pressure and a rotary model pushing hot water through the grounds at high speed. Both machines can make great espresso however rotary machines tend to be quieter, more durable and less likely to fail.
The Boiler
The boiler heats the water to a temperature that is ideal for extraction. The steam that is created will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. During this process, the steam causes pressure to push through the grounds of the coffee. This results in a layer of crema that is then poured over. This is one of the main characteristics of a good espresso.
There are three distinct types of espresso machines, each with different types of pumps and the temperature of the brew. There are many ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.
The first espresso machines were steam type. The earliest espresso machines were steam-type machines. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was created by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semi-automatic one that has an electric pump. These are the images people have when they think of an espresso maker. With a semi-automatic machine you need to grind the beans and then tamp them by hand. However, the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and mechanized consistency.
The Filter
Espresso machines typically have filters that separate the grounds of coffee from hot water. The filter is also a vital element of the temperature control system as it prevents the machine from overheating.
It also aids in flavor, as it allows for a longer bloom time. This helps the beans let their nuances out and provides an opportunity for better extraction.
However it is crucial to keep in mind that even a top filter can make a terrible cup of coffee, because the quality of the beans and extraction are vital.
It's in this area that the magic occurs. This is the reason why espresso tastes so good. The grouphead, sometimes referred to as the brewhead, is where the portafilter (the device you put the ground coffee into) sits when you're making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to produce steam. The steam then pushes hot water into the grounds of the coffee under pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal conditions for brewing because they operate at 1-1.5 bars of pressure. The perfect 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. They are also more mobile than electric steam-driven espresso machines.