How Does Machine Espresso Work?
The machine espresso is made using precise pressure and filter technology that is mind-blowing to make the coffee you love. What exactly is it that makes it work?
Espresso is made 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 primary difference.
The Group Head
The group head is the portafilter that you put in when making espresso. It is responsible for dispersing water into the portafilter and then controlling the pressure that results from the extraction. There are a variety of types of group heads each with its own advantages and drawbacks. Some are designed to provide the stability of temperature while some are specifically designed to handle pre-infusion. Others are made to control the lever. There are some that include a mix of features, like the E61, which is considered to be the most popular among baristas for its ability to offer multiple benefits in one package.
As you can see in the image above, the group head has several notches to put your portafilter, then twist it with your hands to lock it in. There is also a gasket made from rubber that resides inside the notches, which helps create a seal when you insert your portafilter into the machine. The notches allow for the precise placement of the portafilter. This is vital for a consistent extraction.
Apart from allowing you easily connect your portafilter, the group head is also responsible for maintaining an even temperature. This is done by cycling hot water around the portafilter and through the brew-basket to ensure 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 good and a excellent espresso.
The Pump
The motorized pumps used in espresso machines that rotate provide the nine atmospheric bar pressure that is required for espresso extraction. This differs from manually operated piston machines that employ levers. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.
Pumps tend to be cheaper than piston-driven machines and tend to last longer. However, both types of machines could degrade with overuse and insufficient cleaning. They also increase the complexity of mechanical systems that can lead to the cost of even the most basic models.
Some espresso machines do away with the pump completely and employ steam pressure to create espresso. The downside is that the same boiler that produces steam also raises the temperature of the water until it reaches boiling which could lead to over-extraction. In addition these machines typically have to restore their pressure between cups, which requires time and energy.
Many espresso machines make use of a rotary or vibration pump. A vibration model utilizes a rotating disk to generate pressure, while the circular model pushes hot liquid through the ground at high speed. Both machines can make excellent espresso, however rotary machines are more quiet, durable and less likely to break.
The Boiler
The boiler is the component that heats the water to the ideal temperature to extract. The resultant steam then reaches the portafilter, which contains ground espresso beans and is then funneled down into the cup. The steam causes enough pressure to push the coffee grounds through. This produces a layer of crema that is then poured over. This is one of the main characteristics of a great espresso.
There are three types of espresso makers, and they differ in the type of pump they employ and how hot the espresso is. There are various ways in which the brew could be controlled and the size of the cup the machine is capable of making.
The first espresso machines were steam-type. The first espresso machines were steam-type machines. This led to the coffee tasting bitter and burnt. This is why the Milanese makers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.
The most commonly used espresso maker is a semi-automatic machine that has an electric pump. These are the things people think of when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans by yourself The pump, however, regulates the water flow and pressure. This is a great solution that combines human control with mechanized reliability.
The Filter
Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also a crucial element of the temperature control system, as it keeps the machine from overheating.
A filter also improves flavor as it allows for the beans to flower for a longer period of time. This allows the beans to release their nuances and gives the chance for better extraction.
However it is crucial to remember that even a great filter can make a terrible cup of coffee, as the quality of the beans and extraction is still essential.
This is where the magic happens. It's what makes espresso taste great. The grouphead, often called the brew head, is where the portafilter (the device you put the ground coffee into) is placed when you're making espresso.
Steam-driven espresso machines make use of hot water heated in an airtight container to create steam. The steam then pushes hot water through grounds of coffee under high pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to provide the perfect brewing conditions since they operate at 1-1.5 bars of pressure. The perfect 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 ground. They are also more mobile than steam-driven electric coffee machines coffee espresso machines.