9 Things Your Parents Teach You About Machine Espresso
How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to create the delicious coffee we enjoy. What exactly is it?
To make an espresso hot water is pushed under pressure through finely ground coffee espresso machine. The process is similar to making drip coffee. However the pressure is the major difference.
The Group Head
The group head is the portafilter that you place in the espresso maker when making it. It disperses water in the portafilter, and regulates the pressure of the extraction. There are many different types of group heads, each with its own advantages and drawbacks. Some focus on temperature stability, others on pre-infusion options, and others are designed to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas because it offers multiple advantages in one package.
As you can see in the image above the head of the group is fitted with a variety of notches. It is possible to place your portafilter into these notches and twist the head to secure it. There is also a rubber gasket in the notches and helps to create an airtight seal after inserting your portafilter into the machine. The notches on the head allow for an exact placement of the portafilter, which is essential to ensure a consistent extraction.
The group head not only lets you to put in your portafilter easily however, it also keeps the temperature at a constant level. This is achieved by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is at the right level to extract the coffee. This is important because just a few degrees could be the difference between a good and great espresso.
The Pump
Motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure needed to extract espresso. This differs from manually operated piston machines that employ a lever. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.
Pumps are generally less expensive and last for longer than piston-driven machines. However, both types of machines can deteriorate due to excessive use and insufficient cleaning. Pumps are also more complicated mechanically, which could increase the cost of even most basic models.
Certain espresso machines utilize steam pressure instead of a pump in order to brew espresso. This can cause over-extraction because the boiler that makes steam also warms the water to boil. In addition the machines often have to rebuild their pressure between cups, which takes time and energy.
Many espresso machines use an rotary or a vibration pump. A vibration model utilizes an oscillating disk to create pressure, while a circular model pushes hot liquid through the ground at a high speed. Both models are capable of producing excellent decent espresso machine, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the element that heats water to the optimal temperature to extract. The steam that is produced reaches the portafilter which holds the ground espresso coffee and is then pumped into the cup. The steam creates enough pressure to push the coffee grounds through. This creates a crema on the top of the espresso. This is one of the main characteristics of a good pro espresso machine.
There are three kinds of espresso makers. They differ in the type of pump they use and the degree of heat that the espresso is. There are different ways in which the brew could be controlled, as well as the size of the cup that the machine can produce.
The first espresso machines were steam type. They had only one boiler to make steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure, at most. The coffee tasted bitter and burned. This is why Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most commonly used espresso maker is a semi-automatic device with an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic espresso machine, you need to grind the beans and tamp them by hand. The pump regulates the flow of water and pressure. This is an excellent compromise between human touch and the mechanized accuracy.
The Filter
Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also a vital component of the machine's temperature control, as it prevents overheating.
A filter also helps with flavor as it allows for a longer flowering phase. This lets the beans release their nuances, and allows for better extraction.
It is important to remember that even the finest filter could result in a poor 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 delicious. The grouphead (also known as the brewhead) is where you place the portafilter, the device which you put the grounds of your coffee into when making espresso.
Steam-driven espresso machines use hot water heated in an airtight container to create steam. The steam then pushes hot water into the grounds of the coffee under pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the perfect conditions for brewing, since they are only operating at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.
In recent times, espresso machines powered by compressed air-pump have become increasingly popular. They utilize an air compressor to force hot water into the grounds, and are far more portable than electric steam-driven machines.