How Does Machine Espresso Work?

Machine espresso utilizes precise pressure and incredible filter technology to produce the perfect cup of coffee. What exactly is it?

To make an espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee however the main difference lies in the pressure.

The Group Head

The group head is the portafilter is inserted when you are making espresso. It disperses water into the portafilter and controls the pressure of the extraction. There are many different kinds of group heads, each with their unique advantages and disadvantages. Some are designed for temperature stability while others are designed to handle pre-infusion. Others are built to control the lever. Some come with a combination of both, such as the E61. This is a very popular choice for baristas due to the fact that it has multiple advantages in one package.

As you can see in the picture above the head of the group is equipped with several notches. It is possible to place your portafilter inside these notches, and then turn the head around to secure it. A rubber gasket is located in the notches to create a seal while you insert your portafilter. The notches on the head permit a precise position of the portafilter which is vital for an even extraction.

In addition to allowing you effortlessly insert your portafilter the group head is also responsible to ensure that the temperature remains even. It does this by circulating hot water through the brew basket and around the portafilter, ensuring that it's always at the correct temperature to extract. It is crucial to keep in mind that even a tiny deviation can make the difference between a good and a excellent espresso.

The Pump

Unlike manual piston machines, which rely on a lever to pressurize water, rotary espresso machines rely on motorized pumps that provide the nine atmospheric bars of pressure needed for espresso extraction. The pressure is created by drawing tap water from a reservoir, and pumping it through a heat exchanger before it is shot through the ground coffee inside the group head.

Pumps tend to be less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading because of frequent use and poor cleaning. They also increase the complexity of mechanical systems that can lead to an expensive price for even the simplest models.

Some espresso machines can eliminate the pump entirely and use steam pressure to brew espresso. The drawback of this is that the same boiler that produces steam also raises the temperature of water to boiling which can cause over-extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize either a rotary or vibration pump, with a vibration model using a rotating disc bean to cup espresso machine generate the pressure and the rotary model pushing hot water through the grounds at high speed. Both types of machines are capable of producing excellent espresso, but Rotary machines are quieter and more durable than vibration pumps.

The Boiler

The boiler is the one that is used to heat the water to the right temperature to extract. The steam that is created gets to the portafilter which contains the espresso coffee grounds. It is then poured into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This results in a whipped-up top of the espresso. This is a hallmark of a good espresso.

There are three types of espresso makers, which differ in the type of pump they employ and how hot the espresso is. There are a variety of ways to control the brew as well as the size of cup that can be made by the machine.

The first buy espresso machines machines were steam-types. They used a single boiler to make both steam and brew however the pressure they were able to produce was very low - just two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. This is why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most well-known espresso machine is a semiautomatic one with an electric pump. This is what people envision when they think of an cheap espresso machine machine. With a semi-automatic espresso machine, you must grind the beans and then tamp them by hand. However, the pump is able to regulate the flow of water and pressure. This is a great compromise between the human touch and the mechanised accuracy.

The Filter

Espresso machines usually have filters that separate the grounds of coffee from hot water. The filter is also a vital element of the machine's temperature control, as it prevents overheating.

It also helps with flavor, as a filter can allow for a longer bloom time. This helps the beans to release their flavor and gives the chance for better extraction.

It is important to remember that even the finest filter could result in a poor cup of coffee. The quality of the beans, as well as the extraction, are still very important.

This is where the magic happens. It's what makes espresso maker barista taste good. The grouphead (also called the brewhead) is where you place the portafilter, the thingy that you put the coffee grounds in, while making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight container to create steam, which then pushes the hot water through the grounds with high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. However, they are limited in their capacity to create the ideal conditions for brewing as they only operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bars.

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