Nine Things That Your Parent Taught You About Machine Espresso
Nine Things That Your Parent Taught You About Machine Espresso
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How Does Machine Espresso Work?
The machine espresso makes use of precision pressure, and a filter technology that is mind-blowing to create the coffee you love. How exactly does it work?
Espresso is produced by pushing hot water at high pressure through finely-ground coffee. The process is similar to that of making drip coffee. However it is the pressure that makes the main difference.
The Group Head
The group head is the portafilter that you put in when making espresso. It disperses the water into the portafilter, and regulates the pressure of the extraction. There are many different kinds of group heads, each with their own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion capabilities, while others are designed to control the lever. There are some that have a combination of features, such as the E61, which is considered the standard choice for many baristas due to its ability to offer multiple perks in a single package.
As you can see from the above photo the group head is fitted with several notches. It is possible to place your portafilter into these notches and twist the head to secure it. A rubber gasket is located inside the notches, which helps create a seal as you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is crucial for an even extraction.
Aside from allowing you to easily connect your portafilter, the group head is also responsible to ensure that the temperature remains even. This is accomplished by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is always at the right level for extraction. This is crucial, since even a small difference in temperature can make the difference between a excellent and great espresso.
The Pump
In contrast to manual piston machines which use a lever to pressurize water, rotating espresso machines rely upon motorized pumps that provide the nine atmospheric bars of pressure needed to extract espresso. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be less expensive than piston-driven machines, and tend to last longer, although both types of machine can be damaged by excessive use and inadequate cleaning. They also increase the complexity of mechanical systems which can result in costly prices for even the simplest models.
Certain espresso machines do away with the pump entirely and use steam pressure to brew espresso. This can cause over-extraction because the boiler that produces steam also warms the water to boil. In addition the machines often have to restore their pressure between cups, which takes time and energy.
Many espresso machines make use of either a rotary or vibration pump, which is a vibration model that uses a vibrating disc to generate the pressure and an rotary model that pushes hot water through the grounds under high speed. Both types of machines are capable of producing excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.
The Boiler
The boiler is what makes the water warm to a temperature that is ideal to extract. The resultant steam then reaches the portafilter which holds the ground espresso coffee, and gets funnelled down into the cup. In this process, the steam creates pressure that pushes through the grounds of the coffee. This results in a layer crema that is then poured over. This is one of the main characteristics of a good espresso.
There are three kinds of espresso makers, and they differ in the kind of pump they use and how hot the coffee is. There are various ways in which the brew can be controlled, as well as the size of the cup that the machine can produce.
The first espresso machines were steam-type. They employed only one boiler to make steam and brew, but the pressure they could create was minimal - two bars of atmospheric pressure at the most. The coffee tasted bitter and burned. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most well-known espresso maker is a semi-automatic machine with an electric pump. These are the things people think of when they imagine an espresso machine. Semi-automatic machines require you to grind and tamp the beans on your own however the pump controls the water flow and pressure. This is a great compromise between the human touch and the mechanised quality.
The Filter
Espresso machines usually have a filter that separates the coffee grounds from the hot water. The filter is also an essential element of the temperature control system, since it helps prevent the machine from overheating.
It also helps with flavor, as a filter allows for a longer bloom phase. This helps the beans to let their nuances out and provides an opportunity for better extraction.
It is important to keep in mind that even the finest filter could result in a poor cup of coffee. The quality of the beans, and the extraction process remain crucial.
It's in this area that the magic takes place. This is the reason why espresso tastes so good. The grouphead (also called the brewhead) is where you put the portafilter - the thingy used to place the grounds of your coffee into when making espresso.
In the steam-driven espresso machine hot water is heated in an airtight tank to create steam, which then pushes the hot water through espresso coffee machine home the grounds with high pressure. These kinds of machines are typically cheaper and easier to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect conditions for brewing, because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.
In recent years, espresso machines driven by a compressed air pump have become increasingly popular. They use an air compressor to force hot water through the grounds and are much more portable than electric steam-driven machines.