How Does Machine Espresso Work?

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

In order to make professional espresso machine hot water is forced under high pressure through finely ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.

The Head of the Group

The group head is the portafilter that you place in the espresso maker when making it. It disperses water into the portafilter and controls the pressure of the extraction. There are many different kinds of group head, each with their own advantages and disadvantages. Some are designed to provide stability of temperature while others are specifically designed to handle pre-infusion. Others are made to control the lever. There are even some that have a combination of features, like the E61 one, which is the most popular choice among baristas due to its capacity to provide multiple benefits in a single package.

As you can see in the above photo the head of the group is fitted with several notches. You place your portafilter into these notches and twist the head to lock it. A gasket made of rubber is positioned inside the notches to help create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is essential for an efficient extraction.

The group head is not just able to allow the portafilter to be inserted easily however it also keeps the temperature at a constant level. This is accomplished by cycling hot water around the portafilter and through the brew-basket, ensuring that the temperature is at the right level for extraction. This is important, as even a small difference in temperature can be the difference between a good and excellent espresso.

The Pump

The motorized pumps used in rotary espresso machines provide the nine atmospheric bar pressure required for espresso extraction. This is different from manual piston machines which use levers. This pressure builds up by removing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.

Pumps are typically less expensive and last for longer than piston-driven machines. However, both kinds of machines are susceptible to degrading due to overuse and inadequate cleaning. They also increase the complexity of mechanical systems and can lead to a high price tag on even the simplest models.

Some espresso machines remove the pump completely and instead use steam pressure to brew espresso. This can lead to over-extraction as the boiler that produces steam also causes the water to boil. These machines also have to continuously rebuild their pressure between cups. This requires energy and time.

Many espresso machines utilize the rotary or vibration pump, with a vibrating model using a rotating disc to create the pressure, and the rotary model pushing hot water through the grounds under high speed. Both types of machines can make excellent espresso, however the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler is what will heat the water to a temperature that is ideal to extract. The resulting steam is then transferred to the portafilter containing the ground espresso and is then pumped into the cup. The steam causes enough pressure to push the grounds of coffee through. This produces a layer of crema that is then poured over. This is a sign of a great espresso.

There are three kinds of espresso makers, and they differ in the type of pump they use and the degree of heat that the espresso is. There are various ways to control the strength of the brew and the size of cup that can be made by the machine.

The first espresso machines were steam-type. They used one boiler to make both steam and brew, however the pressure they were able to create was minimal - two bars of atmospheric pressure at most. This resulted in the coffee tasting bitter and burnt. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni developed the modern espresso machine.

The most common espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they picture these machines. Semi-automatic machines require you to grind and tamp the beans by yourself however the pump controls the water flow and pressure. This is a great compromise between the human touch and the mechanised quality.

The Filter

Espresso machines typically have filters that separate the grounds of coffee from hot water. The filter is also a crucial component of the temperature control system, as it prevents the machine from overheating.

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

However it is crucial to keep in mind that even a great filter could result in a bad cup of coffee as the quality of the beans and extraction is essential.

It's here that the magic takes place. This is what makes espresso taste so delicious. The grouphead, often referred to as the brew head, is where the portafilter (the thing you put the ground coffee into) is placed when you're making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds at high pressure. They are less expensive and are easier for the user to maintain than pumps-driven models. However, they are not as efficient in their ability to produce the ideal brewing conditions, since they are only operating at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

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