How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. What exactly is it that makes 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 difference is in the pressure.

The Group Head

The group head is the portafilter you insert when brewing espresso. It distributes water into the portafilter, and then regulates the pressure during the extraction. There are a variety of types of group heads, each with their own advantages and drawbacks. Some are designed for stability of temperature while others are designed to handle pre-infusion. Others are built to control the lever. There are even some that have a combination of features, like the E61 that is the classic choice among many baristas due to its ability to offer multiple perks in a single package.

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

The group head not only lets you to put in your portafilter easily however it also keeps an even temperature. This is accomplished by cycling hot water around the portafilter and through the brew-basket to ensure that the temperature is always at the right level to extract the coffee. It is important to remember that even a slight variation can mean the difference between a good and great espresso.

The Pump

The motorized pumps in espresso machines rotary provide nine atmospheric bars of pressure required to extract espresso. This is different from manual piston machines that use a lever. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger before it is shot through the ground coffee in the group head.

Pumps are generally less expensive and last for longer than piston-driven machines. However, both types of machines are susceptible to degrading due to overuse and inadequate cleaning. They also create mechanical complexity which can result in the cost of even the simplest models.

Some espresso machines eliminate the pump completely and instead make use of steam pressure to make espresso. The disadvantage of this is that the boiler that produces steam also raises the temperature of the water to boiling which can cause excessive extraction. The machines also need to continually rebuild their pressure between cups. This requires energy and time.

Many espresso machines employ an rotary or vibrating pump, which has a vibration model that uses a vibrating disc to generate the pressure and rotating models that push hot water through the grounds at high speed. Both machines can make great espresso but rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler is the element that heats the water to the optimal temperature to extract. The steam that is created is then directed to the portafilter, which holds the espresso grounds. It is then poured into the cup. The steam creates enough pressure to push the grounds of coffee through. This results in a layer of crema on top. This is a sign of a great espresso.

There are three types of best espresso machine under 200 makers. They differ in the type of pump they use and how hot the coffee is. There are different ways that the brew can be controlled as well as the size of the cup that the machine is capable of making.

The first espresso machines were steam type. The earliest espresso machines were steam-type machines. The coffee tasted bitter and burnt. The modern espresso machine was developed by the Milanese makers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso machine is a semiautomatic model with an electric pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans on your own while the pump controls the water flow and pressure. This is an excellent compromise between human control and mechanised consistency.

The Filter

Typically, espresso machines use a filter to separate out the grounds of the coffee as they go through the hot water. The filter is also a vital component of the machine's temp control, as it prevents overheating.

It also improves flavor as a filter can allow for a longer bloom phase. This helps the beans to release their flavors and provides an opportunity for a better extraction.

It is important to remember that even the finest filter can produce a bad cup of coffee. The quality of the beans, as well as the extraction, are still crucial.

It's in this area that the magic takes place. This is the reason why espresso tastes so delicious. The grouphead, also called the brewhead, is where the portafilter (the thing you put the coffee ground into) is placed when making espresso.

In a steam-driven espresso machine hot water is heated in an airtight container to produce steam, which then pushes the hot water through the grounds at a high pressure. These machines are less expensive and easier to maintain than pumps-driven models. However, they are not as efficient in their ability to create the ideal brewing conditions, because they operate at 1-1.5 bars of pressure. The perfect shot requires 9-10 bars.

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