10 Tips For Getting The Most Value From Machine Espresso
How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and mind-blowing filter technology to make the perfect cup of coffee. How does it work exactly?
To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main difference.
The Group Head
As the name suggests the group head is where you put your portafilter in when making espresso. It disperses water in the portafilter, and then regulates the pressure during the extraction. There are numerous kinds of group heads each with distinct advantages and drawbacks. Some focus on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. Some come with a combination of both, such as the E61. This is a favorite among baristas because it offers multiple advantages in one package.
As you can see in the above photo the group head is made up of many notches in which you can put your portafilter, then twist it manually to secure it. A gasket made of rubber is placed within the notches to create a seal when you insert your portafilter. The notches allow for precise placement of your portafilter. This is crucial to ensure an even extraction.
In addition to allowing you to easily connect your portafilter, the group head is also responsible to maintain an even temperature. It does this by cycling hot water through the brew pan and around the portafilter to ensure that it is always at the right temperature to extract. This is vital, because even a small difference in temperature can make the difference between excellent and great espresso.
The Pump
In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure that are required to extract espresso. The pressure is created by removing tap water from a reservoir and pumping it through a heat exchanger prior to being shot through the ground coffee inside the group head.
Pumps tend to be less expensive and last longer than piston-driven machines. However, both kinds of machines can degrade due to excessive use and poor cleaning. They also create mechanical complexity that can lead to the cost of even the simplest models.
Certain espresso machines utilize steam pressure instead of a pump to brew espresso. The drawback is that the same boiler that produces steam also increases the temperature of the water to the point of boiling and can result in over-extraction. In addition these machines are often required to restore their pressure between cups, which takes time and energy.
A majority of espresso machines utilize a rotary or vibration pump. A vibration model employs an oscillating disk to create pressure, whereas the circular model pushes hot liquid through the ground at high speed. Both machines can make great espresso, however rotary machines are quieter, more durable and less likely to fail.
The Boiler
The boiler will heat the water to a temperature that is ideal to extract. The steam produced will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. The steam is then channeled into the cup. The steam generates enough pressure to push the grounds of coffee through. This results in a whipped-up top of the espresso. This is a sign of a good espresso.
There are three types of espresso makers, and they differ in the kind of pump they use and the degree of heat that the espresso is. There are coffee espresso machine of ways that the brew may be controlled as well as the size of the cup the machine is capable of making.
The earliest espresso machines were steam-based. They used only one boiler to make both steam and brew however, the pressure they could produce was very low - just two bars of atmospheric pressure at the most. This resulted in the coffee tasting burnt and bitter. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most commonly used espresso machine is a semiautomatic with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp your beans yourself, but the pump regulates the water flow and pressure. This is an excellent compromise between human touch and the mechanized accuracy.
The Filter
Espresso machines typically have filters that separate the grounds of the coffee from hot water. The filter is also a crucial part of the temperature control system, as it prevents the machine from overheating.
It also enhances flavor, since a filter allows for a more prolonged bloom phase. This allows the beans to release their flavors, and improves extraction.
It is important to keep in mind that even the finest filter can make a bad cup of coffee. The quality of the beans as well as the extraction, remain vital.
It's here that the magic occurs. This is what makes espresso taste so good. The grouphead (also known as the brewhead) is where you place the portafilter, the thingy that you put the grounds of your coffee into when making espresso.
Steam-driven espresso machines use hot water heated in an airtight container to produce steam. The steam then moves hot water through the grounds of coffee under high pressure. These types of machines tend to be less expensive and simpler to maintain than pump-driven models. They are however limited 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, compressed air-driven espresso machines have been gaining popularity. They utilize an air compressor to push hot water across the ground and are more mobile than electric steam-driven espresso machines.