How Does Machine Espresso Work?
The machine espresso makes use of precision pressure, and filter technology that is mind-blowing to make the coffee you love. What exactly is it?
To make espresso hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the primary difference.
The Head of the Group
As the name implies, the group head is the place you place your portafilter when brewing espresso. It is responsible for dispersing the water into the portafilter before controlling the pressure that results from the extraction. There are numerous kinds of group heads, each with its own advantages and disadvantages. Some are designed to provide the stability of temperature while some are built to handle pre-infusion. Others are built to control the lever. Some include a combination like the E61. This is a popular choice among baristas as it provides a variety of benefits in a single package.
As you can see in the above image the group head is made up of many notches in which you can put your portafilter, then twist it manually to secure it. There is also a gasket made from rubber that is a part of the notches, which helps create a seal when you insert your portafilter into the machine. The notches on the head allow for an exact positioning of the portafilter which is necessary to ensure a consistent extraction.
The group head is not just able to allow you to put in your portafilter easily, but it also maintains the temperature at a constant level. This is achieved by cycling hot water around the portafilter, and through the brew-basket to ensure that the temperature is always at the right level to extract the coffee. This is important because even a few degrees can make the difference between good and excellent espresso.
The Pump
The motorized pumps in espresso machines rotary provide nine atmospheric bar pressure required to extract espresso. This is different from manual piston machines that rely on a lever. The pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger prior to being pumped through the ground coffee inside the group head.
Pumps are generally cheaper and last longer than piston-driven machines. However, both kinds of machines are susceptible to degrading because of frequent use and poor cleaning. They also make mechanically complex and can lead to costly prices for even the simplest models.
Certain espresso machines eliminate the pump completely and instead use steam pressure to brew espresso. This can result in over-extraction because the boiler that produces steam also causes the water to boil. Additionally, these machines frequently have to rebuild their pressure between cups, which requires time and energy.
Many espresso machines utilize a vibration or rotary pump, with a vibrating model using a vibrating disc that generates the pressure and a rotary model pushing hot water through the grounds under high speed. Both machines can produce excellent espresso, however rotary machines are quieter, more durable and less likely to break.
The Boiler
The boiler is the element which heats the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter containing ground espresso beans and is then pumped down into the cup. During this process the steam causes enough pressure to push the grounds of the coffee through. This results in a crema on the top of the espresso. This is a sign of a great espresso.
There are three kinds of espresso makers, and they differ in the type of pump they employ and the degree of heat that the brew is. There are various ways to control the brew and the size of cup that can be produced by the machine.
The first espresso machines were steam-types. The earliest espresso machines were steam-type machines. This led to the coffee tasting burnt and bitter. This is the reason Milanese makers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.
The most well-known espresso maker is a semi-automatic one that has an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans on your own The pump, however, regulates the water flow and pressure. This is a great compromise between the human touch and mechanized consistency.
The Filter
Typically, espresso machines have filters that separate the grounds of coffee when they pass through the hot water. The filter is also a vital component of the temperature control system since it helps prevent the machine from overheating.
It also helps with flavor, as it lets you enjoy a longer bloom time. This helps the beans to release their flavors and provides an opportunity to improve extraction.
However, it is important to keep in mind that even a top filter can result in a poor cup of coffee as the quality of the beans and extraction is still important.
It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead (also coffee machine called the brewhead) is where you put the portafilter, the device that you use to put the grounds of your coffee into when making espresso.
In an espresso machine that is driven by steam, 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 for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal conditions for brewing because they operate at 1-1.5 bars of pressure. However, the perfect shot requires 9-10 bar.
In recent times, espresso machines powered by compressed air-pump have become increasingly popular. They make use of an air compressor to push hot water across the ground and are much more mobile than electric steam-driven espresso machines.