How Does Machine Espresso Work?
Machine espresso uses precision pressure and mind-blowing filter technology to make the perfect cup of coffee. How does it work exactly?
Espresso is made by pushing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee. However, the pressure is the primary difference.
The Group Head
The name implies the group head is where you put your portafilter in when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure of the resulting extraction. There are several different types of group heads each with its distinct advantages and drawbacks. Some are designed for stability of temperature while others are specifically designed to handle pre-infusion. Others are made to control the lever. There are even some that contain a variety of features, like the E61, which is considered the standard choice for many baristas because of its ability to offer multiple perks in a single package.
As you can see in the above photo, the group head has numerous notches that you can put your portafilter, then twist it by hand to lock it in. A rubber gasket is located in the notches to create a seal when you insert your portafilter. The notches on the head permit an exact position of the portafilter which is necessary for a consistent extraction.
In addition to allowing you easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. This is achieved by cycling hot water around the portafilter, and through the brew-basket, ensuring that the temperature is always at the right level for extraction. It is important to realize that even a slight differences can make the distinction between a great and a great espresso.
The Pump
Unlike manual piston machines, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure necessary for espresso extraction. The pressure builds up by drawing tap water from a reservoir and pumping it through a heat exchanger before being pushed through the ground coffee inside the group head.
Pumps tend to be cheaper and last longer than piston-driven machines. However, both kinds of machines can degrade due to overuse and inadequate cleaning. Pumps are also more complicated mechanically, which can increase the cost of even simplest models.
Some espresso machines employ steam pressure instead of a pump for brewing espresso. This can lead to over-extraction as the boiler that makes steam also heats the water until it comes to a boil. The machines must also constantly rebuild their pressure in between cups. This takes energy and time.
Many espresso machines employ the rotary or vibration pump, with a vibration model that uses a vibrating disc to create pressure, and an rotary model that pushes hot water through the grounds under high speed. Both machines can make excellent espresso, however rotary machines are more stable, quieter and less likely to break.
The Boiler
The boiler is the component that heats water to the ideal temperature to extract. The steam created reaches the portafilter, which is a container for espresso grounds. espresso machines uk is then poured into the cup. During this process the steam causes enough pressure to push the coffee grounds through. This creates a foam on top of the espresso. This is the hallmark of a good espresso.
There are three distinct types of espresso machines, each having different pumps and the temperature of the brew. There are a variety of ways that the brew can be controlled as well as the size of the cup the machine can produce.
The first espresso machines were steam type. The first espresso machines were steam-type machines. This led to the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.
The most popular espresso maker is a semi-automatic machine 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 yourself, but the pump regulates the flow of water and pressure. This is a great solution that combines human control with mechanised consistency.
The Filter
Espresso machines usually use filters that separate the grounds of coffee from hot water. The filter is also an essential part of the machine's temperature control, since it stops overheating.
It also improves flavor, as a filter allows for a longer bloom time. This helps the beans let their nuances out and provides an opportunity for a better extraction.
It is important to remember that even the best filter can result in a bad cup of coffee. The quality of the beans, and the extraction process remain crucial.
It's in this area that the magic happens. This is what makes espresso taste so good. The grouphead, sometimes called the brew head, is the place where the portafilter (the container you place the coffee grounds into) sits when you're making espresso.
In the steam-driven espresso machine hot water is heated in an airtight tank to produce steam, which is then pushed through the grounds at a high pressure. These machines are less expensive and are easier for the user to maintain than pumps-driven models. They are however limited to create the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.
In recent times, espresso machines powered by compressed air-pump have become increasingly popular. They utilize an air compressor to force hot water through the grounds, and are far more portable than electric steam-driven machines.