How Does Machine Espresso Work?
Machine espresso employs precise pressure and amazing filter technology to make the delicious coffee we enjoy. What exactly is it?
In order 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 main difference.
The Head of the Group
The group head is the portafilter you insert when brewing espresso. It disperses the water into the portafilter, and then regulates the pressure of extraction. There are several different types of group head each with its unique advantages and drawbacks. Some focus on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. Some are a combination, such as the E61. This is a favorite among baristas because it offers multiple advantages in a single package.
As you can see from the image above the group head is fitted with a variety of notches. You can place your portafilter into these notches and turn the head around to secure it. A gasket of rubber is situated within the notches to create a seal while you insert your portafilter. The notches allow for the precise placement of the portafilter. This is crucial to ensure an efficient extraction.
The group head not only allows you to place your portafilter easily, but it also maintains a constant temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket, making sure that the temperature is constant to extract the coffee. It is important to remember that even a tiny variation can mean the difference between a good and a excellent espresso.
The Pump
The motorized pumps in espresso machines that rotate provide the nine atmospheric bar pressure that is required for espresso extraction. This is different from manual piston machines that rely on a lever. The pressure is built 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, although both types of machines can degrade with overuse and insufficient cleaning. Pumps are also more complicated mechanically, and can add to the cost of even simpler models.
Some espresso machines eliminate the pump completely and use steam pressure to brew espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of water to the point of boiling which could lead to excessive extraction. In addition these machines are often required to rebuild their pressure between cups, which requires time and energy.
Many espresso machines employ the rotary or vibration pump, with a vibrating model that uses a vibrating disc that generates the pressure and a rotary model pushing hot water through the grounds at high speed. Both types of machine are capable of producing excellent espresso, but the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is the part that heats the water to the ideal temperature to extract. The steam created reaches the portafilter, which is a container for espresso grounds. It is then poured into the cup. The steam causes enough pressure to push the grounds of coffee through. This creates a foam on top of the espresso. This is one of the main characteristics of a great espresso.
There are three types of espresso makers, which differ in the kind of pump they use and how hot the coffee is. There are also different ways in which the brew can be controlled and the dimensions of the cup the machine can make.
The first espresso machines were steam-types. The first espresso machines were steam-type machines. The coffee tasted bitter and burnt. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most popular espresso maker is a semi-automatic one that has 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 flow of water and pressure. This is an excellent compromise between human control get more info and mechanized accuracy.
The Filter
Typically, espresso machines employ a filter to separate out the grounds of coffee as they move through the hot water. The filter is also a vital component of the machine's temp control, as it prevents overheating.
It also improves flavor as a filter lets you enjoy a longer bloom time. This allows the beans to release their flavors, and improves 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, are still very important.
It's here that the magic takes place. This is what makes espresso taste so good. The grouphead, also referred to as the brew head, is where the portafilter (the thing you put the ground coffee in) is placed when making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight container to produce steam. The steam then moves hot water through the grounds of coffee under high pressure. These kinds of machines are typically less expensive and simpler to maintain than pump-driven models. However, they are limited in their capacity to create the ideal brewing conditions, because they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.
In recent years, espresso machines powered by compressed air-pump have become increasingly popular. They utilize an air compressor to push hot water through the grounds and are more portable than steam-driven electric machines.