How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the coffee we love. How exactly does it work?

To make an espresso hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However it is the pressure that makes the main 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 controlling the pressure of the extraction. There are various kinds of group heads, each with their own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion options, and others are designed to control the lever. Some come with a combination of both, such as the E61. This is a preferred choice for baristas due to the fact that it has multiple advantages in one package.

As you can see in the image above, the group head has numerous notches that you can place your portafilter before twisting it with your hands to lock it in. A gasket made of rubber is positioned in the notches to create a seal while you insert your portafilter. The notches on the head permit an exact location of the portafilter which is essential for an even extraction.

The group head is not just able to allow you to place your portafilter easily, but it also maintains the temperature at a constant level. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it's always at the right temperature for extraction. This is important, as even a few degrees can make the difference between a good and great espresso.

The Pump

In contrast to manual piston machines that use a lever to pressurize water, Rotary espresso machines rely on motorized pumps to provide the nine atmospheric bars of pressure that are required to extract espresso. This pressure is generated by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines may degrade because of excessive use and poor cleaning. They also make mechanically complex, which can result in the cost of even the most basic models.

Some espresso machines use steam pressure instead of a pump to make espresso. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. They also have to continuously rebuild their pressure between cups. This takes energy and time.

Many espresso machines utilize either a rotary or vibration pump, which has a vibration model using a vibrating disc to click here create the pressure, and a rotary model pushing hot water through the grounds under high speed. Both types of machine can produce an excellent espresso, but rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is what will heat the water to the perfect temperature for extraction. The resultant steam then reaches the portafilter, which contains the ground espresso coffee, and gets funnelled down into the cup. The steam causes pressure to push through the coffee grounds. This results in a whipped-up the top of the espresso. This is a hallmark of a good espresso.

There are three kinds of espresso makers. They differ in the kind of pump they use and how hot the brew is. There are many ways to control the amount of brew, as well as the size of cup that can be made by the machine.

The earliest espresso machines were steam-based. They employed a single boiler to make steam and brew, however the pressure they were able to produce was very low - just two bars of atmospheric pressure, at most. This resulted in the coffee tasting burnt and bitter. The modern espresso machine was invented by the Milanese producers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semi-automatic machine with an electric pump. When people think of espresso machines, they imagine these machines. If you have a semi-automatic machine you have to grind the beans and tamp them by hand. The pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanised consistency.

The Filter

Espresso machines usually have filters that separate the grounds of the coffee from hot water. The filter is also an essential component of the temperature control system, because it stops the machine from overheating.

A filter also improves flavor as it allows for the beans to flower for a longer period of time. This lets the beans release their flavors, and also allows for better extraction.

However, it is important to remember that even a high-quality filter can make a terrible cup of coffee, as the quality of the beans and extraction are vital.

It's in this area that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, sometimes called the brewhead, is where the portafilter (the thingy you put the coffee ground into) is placed when you're making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. Steam is then pushed through the grounds at high pressure. These kinds of machines are typically cheaper and easier to maintain than pumps-driven models. However, they are limited in their ability to create the perfect conditions for brewing, as they only operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

In recent years, compressed air-pump-driven espresso machines have become more popular. They utilize an air compressor to push hot water through the grounds and are significantly more portable than steam-driven electric machines.