How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly does it work?
To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.
The Group Head
The group head is the portafilter is inserted when you are making espresso. It disperses the water into the portafilter, and then regulates the pressure of the extraction. There are many different types of group heads each with distinct advantages and drawbacks. Some focus on temperature stability, while others on pre-infusion features, and others are designed to control the lever. Some are a combination, like the E61. This is a very popular choice for baristas due to the fact that it has multiple benefits in one package.
As you can see in the above image the group head is made up of several notches where you put your portafilter, then twist it manually to secure it. A gasket made of rubber is placed in the notches to make a seal when you insert your portafilter. The notches on the head allow for an exact placement of the portafilter, which is vital to ensure an efficient extraction.
In addition to allowing you easily insert your portafilter, the group head is responsible to maintain an even temperature. It does this by circulating hot water through the brew container and around the portafilter to ensure that it is always at the correct temperature to extract. It is important to note that even a slight difference can make the difference between a good and great espresso.
The Pump
Motorized pumps in espresso machines rotary provide nine atmospheric bar pressure needed for espresso extraction. This differs from manual piston machines that rely on a lever. This pressure is built up by pumping water through a heat exchanger and then through the ground coffee.
Pumps are generally less expensive than piston-driven machines and tend to last longer, however both types of machines can degrade with overuse and insufficient cleaning. They also create mechanical complexity and can lead to the cost of even the most basic models.
Some espresso machines eliminate the pump completely and instead utilize steam pressure to make espresso. The downside is that the same boiler that produces steam also raises the temperature of the water to boiling, which can lead to over-extraction. In addition, these machines frequently have to restore their pressure between cups, which takes time and energy.
A large majority of espresso machines employ the rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, while the rotating model pushes hot water through the ground at a rapid speed. Both machines can make excellent espresso however rotary machines tend to be more quiet, durable and less likely to break.
The Boiler
The boiler is the one that is used to heat the water to the perfect temperature to extract. The resultant steam then reaches the portafilter which holds ground espresso beans and is then pumped 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 types of espresso machines, each having different types of pumps and the temperature of the brew. There are various ways to control the brew and the size of cup that can be produced by the machine.
The earliest espresso machines were steam type. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most common espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic machine, you must grind the beans and tamp them by hand. The pump provides regulated water flow and pressure. This is an excellent solution that combines human control with mechanised accuracy.
The Filter
Typically, espresso machines employ filters that separate the coffee grounds as they pass through the hot water. The filter is also a vital component of the temperature control system because it stops the machine from overheating.
It also enhances flavor, as a filter can allow for a longer bloom time. This allows beans to release their flavor and gives an opportunity for a better extraction.
It is important to keep in mind that even the finest filter can result in a bad cup of coffee. The quality of the beans and the extraction process are still crucial.
It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is the place where the portafilter (the device you put the coffee ground into) sits when you're making espresso.
Steam-driven espresso machines use hot water that is heated inside an airtight container to create steam. The steam then pushes hot water through grounds of coffee at high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. bean to cup espresso machines are however limited for creating the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent years, espresso machines driven by compressed air-pump are becoming increasingly popular. They use an air compressor to push hot water through the ground. They are also more mobile than electric steam-driven espresso machines.