9 Lessons Your Parents 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. What exactly does it work?

Espresso is created by forcing hot water under high pressure through finely-ground coffee. The process is similar to making drip coffee. However, it is the pressure that makes the main difference.

The Head of the Group

The group head is the portafilter you put in when making top espresso machines. It disperses water into the portafilter, and regulates the pressure of extraction. There are a variety of types of group head, each with their own advantages and disadvantages. Some are designed to provide stability of temperature while others are built to handle pre-infusion. Others are made to control the lever. Some are a combination, such as the E61. This is a very popular choice for baristas since it provides multiple benefits in a single package.

As you can see in the photo above the group head is fitted with a variety of notches. It is possible to place your portafilter in these notches, then turn the head around to secure it. A rubber gasket is located within the notches to create a seal as you insert your portafilter. The notches permit the precise placement of the portafilter. This is vital for an even extraction.

The group head not only allows you to insert your portafilter easily however it also keeps the same temperature. This is achieved by cycling hot water around the portafilter, and through the brew basin, ensuring that the temperature is always at the right level to extract the coffee. This is important because just a few degrees could make the difference between a excellent and great espresso.

The Pump

In contrast to piston machines that are manually operated, which use a lever to pressurize water, the rotary espresso machines use motorized pumps to supply the nine atmospheric bars of pressure that are required to extract espresso. This pressure is generated by pumping water through a heat exchanger and then through the ground coffee.

Pumps tend to be less expensive and last longer than piston-driven machines. However, both types of machines can degrade because of frequent use and poor cleaning. Pumps are also more complicated mechanically, which can raise prices of even most basic models.

Certain espresso machines do away with the pump entirely and employ steam pressure to create espresso. The downside is that the boiler that produces steam also increases the temperature of the water until it reaches boiling which could lead to excessive extraction. They also have to constantly rebuild their pressure in between cups. This takes energy and time.

A majority of espresso machines utilize either a vibration or rotary pump. A vibration model employs a vibrating disk to generate pressure, while a rotating model pushes hot water through the ground at high speed. Both models can make a great espresso, but the rotary models are quieter and more durable than vibration pumps.

The Boiler

The boiler makes the water warm to the right temperature for extraction. The steam that is produced reaches the portafilter, which contains ground espresso beans and is then pumped into the cup. The steam creates pressure that pushes through the coffee grounds. This produces a layer of crema that is then poured over. This is one of the main characteristics of a great espresso.

There are three distinct types of espresso machines, each having different types of pumps and brew temperature. There are a variety of ways in which the brew could be controlled as well as the size of the cup the machine is capable of making.

The earliest espresso machines were steam types. They utilized a single boiler to make both steam and brew, however, the pressure they could create was minimal - two bars of atmospheric pressure, at most. The coffee tasted bitter and burned. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most commonly used espresso maker is a semi-automatic machine with an electric pump. These are what people imagine when they think of an mini espresso machine maker. With a semi-automatic espresso machine, you need to grind the beans and tamp them by hand. However, the pump provides regulated water flow and pressure. This is a perfect compromise between human control and mechanised reliability.

The Filter

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

A filter also helps with flavor because it allows for a longer flowering phase. This allows beans to release their flavor and gives an opportunity for a better extraction.

However it is crucial to keep in mind that even a great filter can produce a bad cup of coffee, because the quality of the beans and extraction is still crucial.

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

Steam-driven espresso machines use hot water that is heated in an airtight container to make steam. The steam then pushes hot water through coffee grounds under high pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the perfect brewing conditions since they are only operating at 1-1.5 bars of pressure. While the perfect shot requires 9-10 bars.

In recent years, compressed-air-pump-driven espresso machines have been gaining popularity. They utilize an air compressor to force hot water through the ground and are more mobile than steam-driven electric espresso machines.