The 9 Things Your Parents Teach You About Machine Espresso
How Does Machine Espresso Work?
Machine espresso makes use of precise pressure and amazing filter technology to make the delicious coffee we enjoy. How exactly does it work?
In order to make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.
The Head of the Group
The group head is the portafilter that you insert when brewing espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure of the extraction. There are a variety of group heads each with their own advantages and drawbacks. Some are designed to provide the stability of temperature while some are designed to handle pre-infusion. Others are made to control the lever. There are even some that include a mix of features, such as the E61 one, which is the most popular choice among baristas due to its ability to offer multiple benefits in one package.
As you can see from the image above the group head has a number of notches. You can place your portafilter in these notches and then turn the head around to secure it. There is also a gasket made from rubber that is a part of the notches, which helps create an airtight seal when you insert your portafilter into the machine. The notches permit the precise placement of the portafilter. This is crucial for a consistent extraction.
The group head does not just allow you to put in your portafilter easily however it also keeps the same temperature. This is done by cycling hot water around the portafilter, and through the brew-basket to ensure that the temperature is at the right level to extract the coffee. This is important because just a few degrees could make the difference between excellent and great espresso.
The Pump
Contrary to manual piston machines that use a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure required for espresso extraction. This pressure is built up by pumping water through a heat exchanger and then through the ground coffee.
Pumps tend to be more affordable and last longer than piston-driven machines. However, both kinds of machines can deteriorate due to excessive use and insufficient cleaning. Pumps are also more complex mechanically, which can raise prices of even simpler models.
Some espresso machines remove the pump completely and use steam pressure to brew espresso. The drawback of this is that the boiler that produces steam also raises the temperature of the water until it reaches boiling which can cause excessive extraction. These machines also have to continuously rebuild their pressure between cups. This requires energy and time.
A majority of espresso machines use either a rotary or vibration pump, with a vibrating model using a vibrating disc to create pressure, and an rotary model that pushes hot water through the grounds under high speed. Both machines can produce excellent espresso, however rotary machines are more stable, quieter and less likely to break.
The Boiler
The boiler is the component that heats the water to the ideal temperature to extract. The resultant steam then reaches the portafilter containing the ground espresso coffee, and gets funnelled down into the cup. During this process, the steam creates pressure that pushes through the grounds of the coffee. This creates a foam on the top of the espresso. This is the hallmark of a good espresso.
There are three types of espresso machines, each having distinct pumps and the temperature of the brew. There are various ways in which the brew could be controlled and the dimensions of the cup the machine is capable of making.
The first buy espresso machine machines were steam types. The earliest espresso machines were steam types. This led to the coffee tasting burnt and bitter. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most well-known espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic espresso machine machines require you to grind and tamp the beans on your own while the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanized accuracy.
The Filter
Espresso machines usually have a filter that separates the grounds of coffee from hot water. The filter is also a vital component of the machine's temp control, as it prevents overheating.
It also enhances flavor, since a filter lets you enjoy a longer bloom time. This helps the beans to release their flavor and gives an opportunity to improve extraction.
However it is crucial to remember that even a top filter can produce a bad cup of coffee as the quality of the beans and extraction is still crucial.
It's in this area that the magic takes place. This is the reason why espresso tastes so delicious. The grouphead, sometimes referred to as the brewhead, 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 make steam. The steam then pushes hot water into the grounds of the coffee under pressure. These machines are cheaper and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect conditions for brewing, since they are only operating at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent years, compressed-air-pump-driven espresso machines home machines have become more popular. They utilize an air compressor to push hot water through grounds and are significantly more portable than steam-driven electric machines.