How Does Machine Espresso Work?

Machine espresso uses precision pressure and amazing filter technology to make the perfect cup of coffee. What 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 that of making drip coffee. However the pressure is the main difference.

The Group Head

The group head is the portafilter you put in when making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure that results from the extraction. There are numerous kinds of group heads each with its own advantages and disadvantages. Some focus on temperature stability, while others on pre-infusion options, and others are designed to control the lever. Some have a combination, such as the E61. This is a very popular choice for baristas as it provides a variety of benefits in one package.

As you can see in the above image The group head features many notches in which you can place your portafilter and twist it with your hands to lock it in. There is also a gasket made from rubber in the notches to help create an airtight seal when you insert your portafilter into the machine. The notches allow for precise placement of your portafilter. This is vital for an accurate extraction.

The group head not only allows you to place your portafilter easily, but it also maintains a constant temperature. This is done by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is constant for extraction. This is important, as just a few degrees could make the difference between excellent and great espresso.

The Pump

In contrast to manual piston machines which rely on a lever that pressurize water, the rotary espresso machines use motorized pumps to provide the nine atmospheric bars of pressure necessary 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 inside the group head.

Pumps tend to be less expensive than piston-driven models, and they tend to last longer. However, both types of machine can become damaged due to excessive use and poor cleaning. Pumps are also more complex mechanically, which could increase the cost of even simplest models.

Some espresso machines do away with the pump completely and employ steam pressure to create espresso. This could lead to over-extraction since the boiler that produces steam also heats the water to boil. They also have to constantly rebuild their pressure in between cups. This takes energy and time.

Many espresso machines make use of either a vibration or rotary pump. A vibration model utilizes a rotating disk to generate pressure, whereas the rotating model pushes hot water through the ground at a fast speed. Both machines can make great espresso however rotary machines tend to be more stable, quieter and less likely to break down.

The Boiler

The boiler is what heats the water to the ideal temperature for extraction. The resulting steam is then transferred to the portafilter which holds the ground espresso coffee, and gets funnelled down into the cup. During this process, steam creates pressure to push through the grounds of the coffee. This creates a crema on top of the best cheap espresso machine. This is a sign of a great espresso.

There are three types of espresso machines, each having different types of pumps and brew temperature. There are many ways to control the strength of the brew and the size of the cup that can be produced by the machine.

The first espresso machines were steam-type. They employed one boiler to create both steam and brew, however, the pressure they could generate was low - only two bars of atmospheric pressure, at most. The coffee tasted bitter and burnt. The modern espresso machine was created by the Milanese manufacturers Luigi Bezzerra & Desiderio Pavoni.

The most commonly used espresso machine with grinder maker is a semiautomatic machine with an electric pump. When people think of espresso machines, they picture these machines. With a semi-automatic espresso machine, you have to grind the beans and then tamp them by hand. The pump controls the flow of water and pressure. This is an excellent compromise between human touch and mechanized consistency.

The Filter

Typically, espresso machines employ filters that separate the grounds of coffee when they pass through the hot water. The filter is also an essential component of the machine's temperature control, since it stops overheating.

It also improves flavor, as it lets you enjoy a longer bloom phase. This lets the beans release their flavors, and also allows for better extraction.

However it is crucial to remember that even a good filter could result in a bad cup of coffee, since the quality of the beans and extraction is still crucial.

This is where the magic happens, it's what makes an espresso really taste good. The grouphead, sometimes referred to as the brew head, is the place where the portafilter (the container you place the ground coffee into) sits when you're making espresso.

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

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