A Provocative Rant About Machine Espresso
A Provocative Rant About Machine Espresso
Blog Article
How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to make the coffee we love. How exactly does it work?
Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, the pressure is the major difference.
The Head of the Group
As the name suggests the group head is where you put your portafilter in when making espresso. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are many different types of group heads each with its own advantages and disadvantages. Some focus on temperature stability, whereas others on pre-infusion capabilities, and still others are designed to control the lever. Some include a combination such as the E61. This is a preferred choice for baristas because it offers multiple benefits in a single package.
As you can see from the above photo, the group head has a number of notches. You place your portafilter in these notches and then twist the head to lock it. A gasket made of rubber is positioned in the notches to create a seal when you insert your portafilter. The notches on the head permit a precise position of the portafilter which is crucial for an efficient extraction.
The group head does not just allow you to insert your portafilter easily however it also keeps a constant temperature. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is constant for extraction. It is crucial to keep in mind that even a slight difference can make the difference between a decent and a excellent espresso.
The Pump
Contrary to manual piston machines which rely on a lever to pressurize water, rotating espresso machines rely upon motorized pumps to provide the nine atmospheric bars of pressure needed to extract espresso. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger before it is shot through the ground coffee inside the group head.
Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can degrade because of frequent use and insufficient cleaning. They also make mechanically complex that can lead to the cost of even the simplest models.
Some espresso machines use steam pressure instead of a pump to make espresso. This could lead to over-extraction since the boiler that produces steam also warms the water to boil. The machines must also constantly rebuild their pressure between cups. This takes energy and time.
Many espresso machines employ an rotary or vibrating pump, with a vibrating model using a vibrating disc that generates the pressure and an rotary model that pushes hot water through the grounds at high speed. Both types of machine are capable of producing excellent espresso, but the rotary models are quieter and more durable than vibration pumps.
The Boiler
The boiler is the one that heats the water to the perfect temperature for extraction. The steam produced gets to the portafilter which holds the espresso grounds. It is then funneled into the cup. The steam creates enough pressure to push the grounds of coffee through. This results in a layer crema that is then poured over. This is one of the hallmarks of a good espresso.
There are three types of espresso makers. They differ in the kind of pump they use and the degree of heat that the coffee is. There are also different ways in which the brew can be controlled, as well as the size 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. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semi-automatic machine with an electric pump. These are what people imagine when they think of an espresso machine. Semi-automatic machines require you to grind and tamp your beans yourself while the pump controls the flow of water and pressure. This is an excellent combination of human control and mechanised accuracy.
The Filter
Typically, espresso machines utilize filters that separate the coffee grounds as they pass through the hot water. The filter is also a vital part of the temperature control system, since it helps prevent the machine from overheating.
A filter also helps with flavor, as it permits an extended flowering time. This lets the beans let their nuances out, and allows for a better extraction.
However, it is important to remember that even a good filter can make a terrible cup of coffee, as the quality of the beans and extraction is essential.
It's in this area that the magic occurs. This is what makes espresso machines espresso machines taste so good. The grouphead, often called the brew head, is the place where the portafilter (the thing you put the coffee ground into) is located when you're making espresso.
In a steam-driven espresso machine, hot water is heated in an airtight container to create steam, which is then pushed through the grounds with high pressure. They are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.
In recent years, compressed air-driven espresso machines have become more popular. They make use of an air compressor to force hot water through the ground and are much more mobile than steam-driven electric espresso machines.