How Does Machine Espresso Work?
The machine espresso uses precise pressure, as well as a filter technology that is awe-inspiring to make the coffee you love. What exactly is it?
Espresso is created by forcing hot water under pressure through finely ground coffee. The process is similar to making drip coffee but the difference is in the pressure.
The Group Head
The name implies, the group head is where you place your portafilter when making espresso. It disperses water into the portafilter and regulates the pressure of the extraction. There are many different kinds of group head, each with their particular advantages and disadvantages. Some focus on temperature stability, others on pre-infusion capabilities, and still others are designed to control the lever. Some include a combination like the E61. This is a favorite among baristas as it provides a variety of benefits in a single package.
As you can see from the above photo the group head is fitted with several notches. You place your portafilter into these notches and turn the head around to secure it. There is also a gasket of rubber which is located inside the notches and helps to create an airtight seal after inserting your portafilter into the machine. The notches allow for precise placement of your portafilter. This is essential for an efficient extraction.
In addition to allowing you to easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. This is done by cycling hot water around the portafilter and through the brew basin, ensuring that the temperature is always at the right level to extract the coffee. It is crucial to keep in mind that even a slight deviation can make the difference between a great and a great espresso.
The Pump
Contrary to manual piston machines which rely on a lever that pressurize water, rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure required to extract espresso. The pressure is built by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be cheaper than piston-driven models, and they tend to last longer, although both types of machines could get damaged through overuse and lack of cleaning. Pumps are also more complicated mechanically, and can add to the cost of even simple models.
Certain espresso machines utilize steam pressure instead of a pump to make espresso. The downside is that the boiler that produces steam also raises the temperature of the water until it reaches boiling, which can lead to excessive extraction. Additionally, these machines frequently have to rebuild their pressure between cups, which takes time and energy.
Many espresso machines make use of the rotary or vibration pump, with a vibration model using a vibrating disc to create the pressure, and an rotary model that pushes hot water through the grounds at high speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to break down.
The Boiler
The boiler heats the water to the ideal temperature to extract. The steam that is produced reaches the portafilter, which contains the ground espresso coffee and is then pumped down into the cup. The steam generates enough pressure to push the grounds of coffee through. This creates a foam on the top of the espresso. This is a hallmark of a good espresso.
There are three kinds of espresso machines, each having a different type of pump and the temperature of the brew. coffee machine for home There are a variety of ways in which the brew could be controlled as well as the dimensions of the cup the machine is capable of making.
The earliest espresso machines were steam type. They employed only one boiler to make both steam and brew but the pressure they could generate was low - only two bars of atmospheric pressure maximum. This resulted in the coffee tasting burnt and bitter. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.
The most commonly used espresso machine is a semiautomatic 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 compromise between the human touch and the mechanised quality.
The Filter
Espresso machines usually have filters that separate the grounds of the coffee from the hot water. The filter is also an essential element of the machine's temperature control, as it helps prevent overheating.
It also aids in flavor, since a filter lets you enjoy a longer bloom phase. This helps the beans release their flavor and gives an opportunity for better extraction.
However it is crucial to keep in mind that even a top filter can result in a poor cup of coffee, because the quality of the beans and extraction is still important.
It's in this area that the magic takes place. This is what makes espresso taste so delicious. The grouphead, often referred to as the brew head, is the place where the portafilter (the device you put the ground coffee into) is placed when you're making espresso.
In the steam-driven espresso machine hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds under high pressure. These types of machines are generally less expensive and easier to maintain than pump-driven models. They are however limited for creating the ideal brewing conditions as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.
In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They use an air compressor to force hot water into the grounds and are more portable than electric steam-driven machines.