How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and amazing filter technology to make the perfect cup of coffee. But how exactly does it work?
Espresso is made by pushing hot water under high pressure through finely ground coffee. The process is similar to making drip coffee, but the key difference is in the pressure.
The Group Head
As the name implies the group head is the place you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure that results from the extraction. There are a variety of group heads each with distinct advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion features, and others are designed to control the lever. Some are a combination, like the E61. This is a popular choice among baristas since it provides multiple benefits in one package.
As you can see in the photo above the group head comes with numerous notches that you can put your portafilter, then twist it by hand to lock it in. There is also a gasket made of rubber which is located inside the notches and helps to create an airtight seal after inserting your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is crucial for an efficient extraction.
The group head not only lets you to put in your portafilter easily, but it also maintains the same temperature. It does this by circulating hot water through the brew basket and around the portafilter to ensure that it's always at the right temperature to extract. This is important, as even a small espresso machine difference in temperature can make the difference between a excellent and great espresso.
The Pump
Motorized pumps in rotary espresso machines provide the nine atmospheric bar pressure needed for espresso extraction. This is different from manual piston machines that use levers. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be less expensive than piston-driven machines and tend to last longer, but both types of machines may get damaged through overuse and lack of cleaning. They also create mechanical complexity, which can result in the cost of even the simplest models.
Some espresso machines employ 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 until it comes to a boil. These machines also have to constantly rebuild their pressure between cups. This requires energy and time.
Many espresso machines utilize either a rotary or vibration pump, with a vibration model that uses a vibrating disc to generate the pressure and an rotary model that pushes hot water through the grounds at high speed. Both machines can make excellent espresso, but rotary machines are more stable, quieter and less likely to break down.
The Boiler
The boiler is the one that heats the water to the right temperature for extraction. The steam that is created is then directed to the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. In this process, the steam creates pressure to push through the coffee grounds. This creates a crema on top of the espresso. This is the hallmark of a good espresso.
There are three types of espresso capsule machine makers, and they differ in the type of pump they use and how hot the coffee is. There are also different ways in which the brew can be controlled as well as the dimensions of the cup the machine is capable of making.
The earliest espresso machines were steam-based. The earliest espresso machines uk machines were steam types. The coffee tasted bitter and burnt. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most commonly used espresso maker is a semi-automatic device that has an electric espresso maker pump. These are what people imagine when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans yourself, but the pump regulates the flow of water and pressure. This is a fantastic compromise between human control and mechanized consistency.
The Filter
Typically, espresso machines employ filters that separate the grounds of coffee when they pass through the hot water. The filter is also a crucial element of the temperature control system, as it prevents the machine from overheating.
It also improves flavor, as a filter allows for a longer bloom phase. This allows beans to release their nuances and gives an opportunity for a better extraction.
However, it is important to keep in mind that even a high-quality filter can make a terrible cup of coffee as the quality of the beans and extraction are important.
This is where the magic happens, it's the thing that makes espresso taste great. The grouphead (also known as the brewhead) is where you put the portafilter, the thingy that you put the coffee grounds into, when making espresso.
In the steam-driven espresso machine hot water is heated in an airtight container to create steam. This then pushes the hot water through the grounds at high pressure. These kinds of machines tend to be less expensive and simpler to maintain than pumps-driven models. However, they are limited in their ability to create the ideal brewing conditions, as they only operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bars.
In recent years, compressed-air-pump-driven espresso machines have become more popular. They use an air compressor to force hot water through grounds and are significantly more portable than electric steam-driven machines.