How Does Machine Espresso Work?

Machine espresso coffee machine with milk frother utilizes precise pressure and mind-blowing filter technology to make the perfect cup of coffee. How does it work exactly?

Espresso is produced by pushing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee. However, the pressure is the primary difference.

The Head of the Group

The name implies the group head is where you insert your portafilter when brewing espresso. It disperses water into the portafilter, and then regulates the pressure of extraction. There are several different types of group heads each with its own advantages and disadvantages. Some are designed for stability of temperature while others are designed to handle pre-infusion. Others are built to control the lever. Some are a combination, like the E61. This is a popular choice among baristas since it provides multiple advantages in one package.

As you can see in the picture above the group head is fitted with several notches. It is possible to place your portafilter in these notches and then turn the head around to secure it. A gasket made of rubber is placed in the notches to make a seal when you insert your portafilter. The notches on the head permit an exact placement of the portafilter, which is necessary for an efficient extraction.

The group head not only allows you to insert your portafilter easily, but it also maintains a constant temperature. It does this by cycling hot water through the brew basket and around the portafilter, ensuring that it is always at the correct temperature to extract. It is important to realize that even a slight variation can mean the difference between a good and a excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever to pressurize water, rotary best espresso machine machines rely on motorized pumps that provide the nine atmospheric bars of pressure required for espresso extraction. The pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior to it is shot through the ground coffee in the group head.

Pumps tend to be cheaper than piston-driven models, and they tend to last longer, although both types of machine can get damaged through overuse and lack of cleaning. They also make mechanically complex, which can result in costly prices for even the simplest models.

Some espresso machines make use of steam pressure instead of a pump for brewing espresso. The drawback of this is that the same boiler that produces steam also increases the temperature of the water to boiling which can cause excessive extraction. In addition, these machines frequently have to restore their pressure between cups, which requires time and energy.

A majority of espresso coffee machines machines utilize a rotary or vibration pump. A vibration model utilizes a vibrating disk to generate pressure, whereas a rotating model pushes hot water through the ground at high speed. Both types of machines can produce an 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 for extraction. The steam that is created gets to the portafilter which holds the espresso grounds. The steam is then channeled into the cup. During this process, steam creates pressure and pushes through the grounds of the coffee. This results in a layer crema on top. This is a sign of a great espresso.

There are three types of espresso makers. They differ in the kind of pump they use and the degree of heat that the espresso is. There are different ways to control the brew as well as the size of cup that can be made by the machine.

The earliest espresso machines were steam type. They had only one boiler to make both steam and brew however, the pressure they could produce was not very high - two bars of atmospheric pressure at most. This resulted in the coffee tasting bitter and burnt. The modern espresso machine was created by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most common espresso machine is a semiautomatic that has an electric pump. This is what people envision when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans by yourself, but the pump regulates the water flow and pressure. This is an excellent compromise between human control and mechanised accuracy.

The Filter

Espresso machines typically use filters that separate the grounds of coffee from hot water. The filter is also a vital component of the machine's temp control, since it helps to prevent overheating.

It also enhances flavor, as a filter allows for a longer bloom phase. This helps the beans to release their nuances and gives the chance for better extraction.

However, it is important to keep in mind that even a high-quality filter could result in a bad 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 good. The grouphead, often referred to as 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 that is heated inside an airtight container to make steam. The steam then pushes hot water through the grounds of coffee under high pressure. These kinds of machines are generally less expensive and simpler to maintain than pumps-driven models. They are however limited in their ability for creating the ideal conditions for brewing, as they operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

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