5 Laws That Will Help The Machine Espresso Industry
How Does Machine Espresso Work?
Machine espresso utilizes precise pressure and amazing filter technology to make the perfect cup of coffee. How exactly does it work?
Espresso is created by forcing hot water under 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 put in when making espresso. It distributes water into the portafilter and regulates the pressure of the extraction. There are numerous kinds of group heads, each with its own advantages and drawbacks. Some focus on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some have a combination of features, such as the E61 that is the standard choice for many baristas due to its capacity to provide multiple benefits in a single package.
As you can see in the above image, the group head has several notches where you place your portafilter and twist it by hand to secure it. A gasket made of rubber is placed in the notches to create a seal while you insert your portafilter. The notches on the head permit a precise positioning of the portafilter which is vital for an even extraction.
In addition to allowing you to easily insert your portafilter, the group head is also responsible for maintaining an even temperature. It does this by circulating hot water through the brew basket and around the portafilter to ensure that it's always at the correct temperature for extraction. It is important to remember that even a few degree difference can make the difference between a good and a great espresso.
The Pump
In contrast to manual piston machines which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to deliver the nine atmospheric bars of pressure needed to extract espresso. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.
Pumps tend to be cheaper than piston-driven models, and they tend to last longer, although both types of machines may get damaged through overuse and lack of cleaning. They also increase the complexity of mechanical systems and can lead to an expensive price for even the most basic models.
Some espresso machines use steam pressure instead of a pump for brewing espresso. This can cause over-extraction because the boiler that makes steam also causes the water to boil. These machines also have to constantly rebuild their pressure in between cups. This requires energy and time.
Many espresso machines employ the rotary or vibration pump, with a vibration model using a rotating disc that generates the pressure, and a rotary model pushing hot water through the grounds 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 is the component that heats the water to the optimal temperature to extract. The steam created will eventually reach the portafilter, which is the container that holds the espresso coffee grounds. It is then pumped into the cup. The steam creates pressure to push through the coffee grounds. This creates a crema on the top of the espresso. This is a sign of a good espresso.
There are three kinds of espresso makers. They differ in the kind of pump they use and the degree of heat that the brew is. There are various ways in which the brew can be controlled and the size of the cup the machine is capable of making.
The first espresso machines were steam-type. They used a single boiler to make both steam and brew but the pressure they could generate was low - only two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was designed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semi-automatic device that has an electric pump. When people think of espresso machines, they think of these machines. With a semi-automatic machine, you must grind the beans and tamp them yourself but the pump is able to regulate the flow of water and pressure. stay with me is a fantastic combination of human control and mechanised accuracy.
The Filter
Espresso machines usually have a filter that separates the grounds of coffee from hot water. The filter is also a vital part of the machine's temperature control, as it prevents overheating.
A filter also improves flavor since it allows for a longer flowering phase. This helps the beans to let their nuances out and provides an opportunity for a better extraction.
It is important to remember that even the best filter could result in a poor cup of coffee. The quality of the beans and the extraction process, remain vital.
It's in this area that the magic occurs. This is the reason why espresso tastes so good. The grouphead (also called the brewhead) is where you put the portafilter, which is the thingy which you put the coffee grounds in, when making espresso.
Steam-driven espresso machines make use of hot water that is heated in an airtight container to create steam. The steam then pushes hot water through grounds of the coffee under pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. They are however limited to create 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, compressed air-pump-driven espresso machines have become more popular. They use an air compressor to force hot water through the grounds, and are far more portable than electric steam-driven machines.