Enrique Virgo

How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to make the perfect cup of coffee. How exactly does it work?

Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to making drip coffee, but the major difference is in the pressure.

The Group Head

As the name implies, the group head is the place you put your portafilter in when making espresso. It disperses the water into the portafilter, and then regulates the pressure of extraction. There are various kinds of group head each with its unique advantages and disadvantages. Some are focused on temperature stability, some on pre-infusion capabilities, while others are designed to control the lever. Some have a combination, like the E61. This is a preferred choice for baristas due to the fact that it has multiple benefits in one package.

As you can see in the image above the head of the group has a number of notches. It is possible to place your portafilter in these notches, then twist the head to lock it. There is also a gasket made from rubber that is a part of the notches and helps to create a seal when you insert your portafilter into the machine. The notches on the head permit an exact placement of the portafilter, which is essential for a consistent extraction.

The group head not only allows you to insert your portafilter easily, but it also maintains the temperature at a constant level. This is done by cycling hot water around the portafilter, and through the brew-basket, making sure that the temperature is constant for extraction. It is important to realize that even a tiny variation can mean the difference between a good and excellent espresso.

The Pump

The motorized pumps in rotary Espresso coffee machine home machines supply the nine atmospheric bar pressure required for espresso extraction. This differs from manual piston machines that rely on a lever. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps are generally more affordable and last longer than piston-driven machines. However, both types of machines can deteriorate due to overuse and poor cleaning. They also create mechanical complexity, which can result in the cost of even the most basic models.

Some espresso machines employ steam pressure instead of a pump for brewing espresso. The drawback is that the same boiler that produces steam also increases the temperature of the water to boiling which can cause excessive extraction. They also have to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines make use of either a vibration or rotary pump. A vibration model uses the vibrating disk to create pressure, while a rotary model pushes hot water through the ground at a rapid speed. Both models can make excellent espresso, however rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the part which heats the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter containing the ground espresso coffee and is then funneled down into the cup. The steam is able to create enough pressure to push the coffee grounds through. This creates a foam on the top of the espresso. This is a sign of a good espresso.

There are three different types of espresso machines, each with distinct pumps and the temperature of the brew. There are different ways to control the amount of brew, as well as the size of the cup that can be produced by the machine.

The first espresso machine sale machines were steam types. They utilized one boiler to make both brew and steam, however, the pressure they could create was minimal - two bars of atmospheric pressure at the most. This led to the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most common professional espresso maker machine is a semiautomatic model with an electric pump. When people think of espresso machines, they envision these machines. If you have a semi-automatic espresso machine machine you have to grind the beans and tamp them by hand, but the pump is able to regulate the flow of water and pressure. This is a perfect combination of human control and mechanized consistency.

The Filter

Typically, espresso machines utilize filters that separate the coffee grounds as they pass through the hot water. The filter is also an essential element of the temperature control system as it prevents the machine from overheating.

It also aids in flavor as a filter lets you enjoy a longer bloom time. This allows the beans to let their nuances out, and also allows for better extraction.

It is important to remember that even the finest filter can make a bad cup of coffee. The quality of the beans, and the extraction, are still very important.

It's here that the magic happens. This is what makes espresso taste so delicious. The grouphead, sometimes referred to as the brew head, is where the portafilter (the container you place the ground coffee in) is located when you're making espresso.

Steam-driven espresso coffee machines machines make use of hot water that is heated inside an airtight container to create steam. The steam then pushes hot water into the grounds of the coffee under pressure. These kinds of machines are typically less expensive and easier to maintain than pumps-driven models. However, they are limited in their capacity to create the perfect brewing conditions because they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bar.

In recent years, espresso machines powered by compressed air-pump are becoming increasingly popular. They utilize an air compressor to force hot water into the grounds, and are far more portable than steam-driven electric machines.