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How Does Machine Espresso Work?

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

In order to make 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 Head of the Group

As the name suggests the group head is where you place your portafilter when brewing professional espresso maker. It is responsible for dispersing the water into the portafilter and then controlling the pressure of the resulting extraction. There are several different types of group heads, each with their particular advantages and disadvantages. Some are designed for stability in temperature, while others are designed to handle pre-infusion. Others are made to control the lever. Some come with a combination of both, like the E61. This is a very popular choice for baristas because it offers multiple benefits in one package.

As you can see in the photo above the head of the group is fitted with a variety of notches. You can place your portafilter in these notches and then turn the head around to secure it. There is also a rubber gasket 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 allow for an exact position of the portafilter which is crucial for an efficient extraction.

The group head is not just able to allow you to insert your portafilter easily but also maintains the same temperature. This is achieved by cycling hot water around the portafilter, and through the brew-basket, making sure the temperature is always right for extraction. It is important to note that even a few degree variation can mean the difference between a good and a great espresso.

The Pump

The motorized pumps that are used in rotary espresso machines supply the nine atmospheric bar pressure needed to extract espresso. This is different from manually operated piston machines that employ levers. The pressure is created by pumping water through a heat-exchanger and then through the ground coffee.

Pumps tend to be more affordable and last longer than piston-driven machines. However, both types of machines can degrade due to overuse and inadequate cleaning. Pumps are also more complicated mechanically, which could increase prices of even simple models.

Some espresso machines employ steam pressure instead of a pump to make barista espresso coffee machine. The downside is that the same boiler that produces steam also increases the temperature of water to the point of boiling and can result in excessive extraction. These machines also have to continuously rebuild their pressure between cups. This requires energy and time.

Many espresso machines make use of an rotary or vibrating pump, with a vibrating model that uses a vibrating disc that generates the pressure and the rotary model pushing hot water through the grounds at high speed. Both machines can make excellent espresso, however rotary machines are more stable, quieter and less likely to fail.

The Boiler

The boiler is the one that is used to heat the water to the right temperature for extraction. The steam that is produced reaches the portafilter, which contains ground espresso beans and is then pumped down into the cup. During this process the steam is able to create enough pressure to push the grounds of the coffee through. This produces a layer of crema on top. This is a hallmark of a good espresso.

There are three types of espresso makers, which differ in the kind of pump they use and the degree of heat that the best Budget espresso machine is. There are a variety of ways in which the brew can be controlled as well as the size of the cup the machine can produce.

The earliest espresso machines were steam types. They used one boiler to make steam and brew, however the pressure they were able to generate was low - only two bars of atmospheric pressure maximum. The coffee tasted bitter and burned. This is why Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most common espresso machine is a semiautomatic one with an electric pump. When people think of espresso machines, they envision these machines. Semi-automatic machines require you to grind and tamp your beans yourself, but the pump regulates the flow of water and pressure. This is a fantastic combination of human control and mechanised accuracy.

The Filter

Espresso machines usually use a filter that separates the coffee grounds from the hot water. The filter is also an essential component of the machine's temperature control, since it stops overheating.

It also enhances flavor as a filter lets you enjoy a longer bloom phase. This helps the beans release their flavor and gives an opportunity to improve 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, remain vital.

It's here that the magic occurs. This is the reason why espresso tastes so delicious. The grouphead, often called the brew head, is where the portafilter (the container you place the coffee ground into) is placed when making espresso machine coffee.

Steam-driven espresso machine coffee machines make use of hot water that is heated inside an airtight container to produce steam. The steam then pushes hot water through the grounds of the coffee under pressure. These kinds of machines are typically less expensive and easier to maintain than pump-driven models. They are however limited for creating the ideal conditions for brewing since they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

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