10 Things That Your Family Teach You About Machine Espresso

How Does Machine Espresso Work?

Machine espresso makes use of precise pressure and mind-blowing filter technology to create the delicious coffee we enjoy. How exactly does it work?

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

The Group Head

The group head is the portafilter that you insert when brewing espresso. It disperses water in the portafilter and regulates the pressure during the extraction. There are many different types of group heads, each with its own advantages and drawbacks. Some are specifically designed for the stability of temperature while some are designed to handle pre-infusion. Others are made to control the lever. Some have a combination of features, like the E61, which is considered the standard choice for many baristas because of its ability to provide multiple benefits in one package.

As you can see in the above image the group head is made up of several notches to place your portafilter and twist it manually to lock it in. There is also a rubber gasket that is a part of the notches and helps to create an airtight seal when you insert your portafilter into the machine. The notches permit precise placement of the portafilter. This is vital for an accurate extraction.

The group head not only allows the portafilter to be inserted easily however, it also keeps the same temperature. It does this by cycling hot water through the brew basket and around the portafilter to ensure that it's always at the correct temperature for extraction. This is important because even a few degrees can be the difference between a good and excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure required to extract espresso. This pressure builds up by drawing tap water from a reservoir, and pumping it through a heat exchanger before being pushed through the ground coffee in the group head.

Pumps tend to be less expensive than piston-driven machines, and they tend to last longer. However, both types of machine can degrade with overuse and insufficient cleaning. They also increase the complexity of mechanical systems and can lead to an expensive price for even the simplest models.

Some espresso machines remove the pump entirely and use steam pressure to brew espresso. The drawback is that the boiler that produces steam also raises the temperature of water to the point of boiling which could lead to over-extraction. The machines must also constantly rebuild their pressure in between cups. This requires energy and time.

Many espresso machines make use of the rotary or vibration pump. A vibration model utilizes an oscillating disk to create pressure, while the Rotary model pushes hot coffee through the ground at a rapid speed. Both machines can produce excellent espresso, but rotary machines are quieter, more durable and less likely to break.

The Boiler

The boiler will heat the water to the right temperature for extraction. The resulting steam reaches the portafilter, which contains the ground espresso coffee, and is then pumped into the cup. During this process the steam generates enough pressure to push the grounds of the coffee through. This results in a whipped-up top of the espresso. This is the hallmark of a great espresso.

There are three different types of espresso machines, each with distinct pumps and the temperature of the brew. There are a variety of ways in which the brew can be controlled as well as the size of the cup that the machine can make.

The first espresso machines were steam type. They used one boiler to create both brew and steam, but the pressure they could produce was very low - just two bars of atmospheric pressure, at most. This led to the coffee tasting bitter and burnt. The modern espresso machine was developed by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most well-known espresso maker is a semiautomatic machine that has an electric pump. When people think of espresso machines, they envision these machines. With a semi-automatic machine, you need to grind the beans and tamp them by hand. The pump controls the flow of water 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 the coffee espresso machine from hot water. The filter is also a vital component of the machine's temp control, since it stops overheating.

A filter also improves flavor, as it permits a longer flowering phase. This allows beans to let their nuances out and provides an opportunity for better extraction.

However it is crucial to remember that even a good filter can make a terrible cup of coffee as the quality of the beans and extraction are crucial.

It's here that the magic happens. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is where the portafilter (the thingy you put the ground coffee 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 cheaper and easier for the owner to maintain than pumps-driven models. They are however limited in their ability to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The ideal shot requires 9-10 bars.

In recent years, compressed air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to push hot water into the grounds and are much more portable than electric steam-driven machines.