How Does Machine Espresso Work?
The machine espresso coffee machine with milk frother makes use of precision pressure, and filter technology that is awe-inspiring to create the coffee you love. How exactly does it work?
To make an espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, however the main difference lies in the pressure.
The Head of the Group
As the name implies, the group head is where you insert your portafilter when making espresso. It disperses water in the portafilter, and regulates the pressure of extraction. There are a variety of group heads each with their own advantages and drawbacks. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. There are also some that come with a range of features, such as the E61, which is the most popular choice among baristas due to its ability to offer multiple benefits in a single package.
As you can see in the photo above, the group head is equipped with several notches. You place your portafilter into these notches and twist the head to lock it. There is also a gasket of rubber which is located inside the notches and helps to create a seal when you insert your portafilter into the machine. The notches on the head permit a precise location of the portafilter which is crucial for an efficient extraction.
The group head not only lets you to insert your portafilter easily but also maintains an even temperature. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant for extraction. This is crucial, since even a few degrees can be the difference between a good and excellent espresso.
The Pump
The motorized pumps that are used in espresso machines that rotate provide the nine atmospheric bar pressure required to extract espresso. This differs from manual piston machines that rely on levers. This pressure is built up by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be cheaper and last longer than piston-driven machines. However, both types of machines may degrade due to excessive use and insufficient cleaning. They also create mechanical complexity that can lead to the cost of even the simplest models.
Certain espresso machines do away with the pump completely and instead employ steam pressure to create espresso. The drawback is that the boiler that produces steam also raises the temperature of water to boiling which could lead to over-extraction. In addition these machines are often required to rebuild their pressure between cups, which requires time and energy.
A large majority of espresso machines employ either a vibration or rotary pump. A vibration model utilizes an oscillating disk to create pressure, while a rotary model pushes hot water through the ground at high speed. Both types of machine are capable of producing excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler will heat the water to the right temperature for extraction. The steam produced gets to the portafilter which is the container that holds the espresso best coffee espresso machine grounds. It is then poured into the cup. The steam creates pressure to push through the coffee grounds. This results in a whipped-up the top of the espresso. This is one of the main characteristics of a good espresso.
There are three kinds of espresso machine with grinder makers. They differ in the kind of pump they use and how hot the brew is. There are various ways that the brew can be controlled as well as the dimensions of the cup the machine can make.
The first espresso machines were steam-type. They used one boiler to create both steam and brew but the pressure they could produce was not very high - two bars of atmospheric pressure maximum. The coffee machines espresso tasted bitter and burned. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans yourself, but the pump regulates the water flow and pressure. This is a great compromise between the human touch and mechanized consistency.
The Filter
Typically, espresso machines use filters to separate the coffee grounds as they pass through the hot water. The filter is also an important part of the temperature control system because it stops the machine from overheating.
A filter can also help with flavor since it allows for a longer flowering period. This lets the beans release their flavors, and allows for better extraction.
It is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans and the extraction, remain vital.
This is where the magic happens. It's what makes an espresso really taste great. The grouphead (also called the brewhead) is where you put the portafilter - the thingy used to place the coffee grounds in, when making espresso.
In a 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 kinds of machines are typically less expensive and simpler to maintain than pump-driven models. They are however limited in their ability to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, espresso machines powered by a compressed air compressor have become increasingly popular. They utilize an air compressor to push hot water through the ground and are much more mobile than steam-driven electric espresso machines.