How Espresso Machines Work: A Look at Technology & History
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How Espresso Machines Work: A Look at Technology & History

Espresso changed coffee for good. This is the history of how the technology evolved.

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Noah Nighswonger

Full time barista in New York City. Part time coffee reviewer.

Coffee brewing and cafes have been around for hundreds of years. However, it wasn’t until the late 19th century that espresso made its way onto the scene.

Before espresso, it was normal for brew times to exceed five minutes.

Five minutes doesn’t sound too troubling for people who brew pour overs at home, but from the perspective of a barista in a busy café, it’s not optimal.

Espresso became the solution to this problem.

In this article, we’ll take a closer look at the interplay between technology and coffee as a beverage.

Steam brewing and early attempts

In 1884 a patent was issued to Angelo Moriondo for a machine that produced coffee through steam usage. This machine had a large boiler that was heated to a mere 1.5 bars of pressure. The water was then pushed to the coffee, where a second boiler produced steam to finish brewing the coffee.

The next individuals who made a significant impact on espresso were Luigi Bezzerra and Desiderio Pavoni.

Early espresso at the Milan Fair in 1906 (Photo: Image: WikiMedia/Public Domain)

Bezzerra made significant improvements; a couple included a portafilter and more brew heads. The boiler on his machine was larger and had chambers filled with water that was then heated. Water and steam would then be pushed through tamped coffee, which was another difference from Moriondo, who only had a large bed of coffee. However, the heated water was quite hot, reaching upwards of 250 degrees Fahrenheit.

Bezzerra’s machine had a radiator that could cool the water to an optimal temperature before making contact with the coffee. Bezzera’s espresso-making ability did fall victim to the ability to produce consistent shots. The water was heated over an open flame, so it was difficult to control temperature pressure.

In 1903 Pavoni bought Bezerra’s patents. Pavoni created the first pressure release valve for espresso machines. He also added a steam wand that collected the excess from the machine’s boiler. Pavoni and Bezerras’ first machine was the Ideale. It was introduced at the 1906 Milan Fair.

The lever & 9 bars

Later there were ways discovered at increasing pressure without sacrificing the taste of coffee.

Achille Gaggia was the man that was able to do that. Gaggia began working in the coffee realm in 1930, but it wasn’t until 1948 that his first espresso machine was introduced. 

One of his changes revolutionized how espresso was made and brought about the terminology that is still used to this day.

Some espresso makers, for example La Pavoni Europiccola, still use levers to create pressure. (Source: Flickr CC | adambarkley)

Gaggia patented a spring-piston lever that further pressurized the water that was already forced from a cylinder due to steam pressure.

The lever’s pressure was 8-10 bars, a huge difference in relation to the 1.5-2 previously known.

This also meant that steam was not necessary to create pressure anymore.

The lever was pulled by the barista, and that is where the expression, “pulling an espresso shot,” came from. Another byproduct of Gaggia’s invention was something that’s closely related to espresso today: Crema.

Faema and the E61

In 1961 the Faema E61, invented by Ernesto Valente, came onto the scene. Valente took away the lever and used a motorized pump to send water to a boiler. A heat exchanger was also introduced to keep water at a desired temperature. The E61 is considered to be a big milestone within coffee history.

Other qualities of life changes have been made within espresso machines over the years, but the E61 ushered in the modern era of what we know as espresso machines. Machines have become more optimized with electrical elements, computerized measurements by volume or weight, and digital interfaces.

The original E61 patent, signed by Ernesto Valente

The Pump

In modern espresso-making, there are two pumps that you can choose to have in your espresso machine, vibratory and rotary.

  • A vibratory pump is electromagnetic. A piston is attached to a magnet that sits within a metal coil. The electrical current runs through the coil having the magnet move the piston, pushing water through the machine.
  • A rotary pump is mechanical. There is a motor spinning a disc that is within a round chamber. The disc is split into sections by vanes. With the disc spinning, the vanes will press against the wall outside the chamber. This decreases the size of the sections, which then creates pressure. Water enters when the sections are still large and then gets pushed out as the sections get smaller.

Although they operate differently, they are the best pumps in pulling espresso. The only specification that would sway your decision on which one to get is how long they last and their ease of replaceability.  

Vibratory pumps are inexpensive, easy to replace, and small; however, they are a bit louder in comparison to a rotary pump and only last five to six years. Rotary pumps have a longer lifespan and are quieter; however, they are larger than a vibratory pump.

  • Lever machines could find their spot in the discussion here too. Lever machines aren’t too common, but they are around. The company I work for has a lever espresso machine at our flagship location. It’s not as if the barista is continually pulling a lever in a pumping motion to get the pressurized water out for a shot of espresso. Water is already heated and held in a chamber that is somewhat pressurized, but the level pull adds the last bit of pressure needed for the 9 bars needed to pull an espresso shot.

The Boiler 

There are different types of boilers you would want to choose from in an espresso machine: single, dual, heat exchange, and thermocoil. In single boilers, there are two thermostats with one heating element. One thermostat is for brewing coffee, and the other is for boiling water to produce steam.

In dual boilers, the pump sends water to the two separate boilers. One boiler heats water to boiling while the other heats water to brew temp. Most of these machines will have a PID, which allows specific temperatures to be set for the most control.

  • Heat Exchanger machines only have one boiler. The water is only used to make steam while another water line runs into the boiler from the pump. That water line connects to a copper pipe that lies inside the boiler. While the water is brought to steam in the boiler, it heats the water in the copper pipe without causing it to boil. This allows the individual to steam milk and pull espresso simultaneously, unlike a single boiler. In a single boiler, you can only do one at a time. The downside to heat exchangers is that the brewing temperature is wildly inconsistent because the water can overheat if left in the copper pipe for too long.
  • Thermocoil machines allow for pulling espresso and steaming at the same time. The water has a reservoir, and when water is needed, it passes through a single tube to be heated. In this system, water is heated more quickly and evenly since it moves through the chamber in a circular motion. Although thermocoil machines offer consistency, they are unable to pull back-to-back espresso shots and steaming. After a round of steaming and brewing, the machine needs time to reheat water for the next attempt.

With all that in mind, you would have to determine what you would like from your at-home espresso machine and how much you’re willing to spend.

You might want to check out the Gaggia Classic Pro and the Rancilio Silvia for single boiler machines.

For dual boiler machines, you might want to check out the La Marzocco Linea Mini and the Breville Dual Boiler.

You might want to check out the Rocket Espresso Milano and the Bezzera Strega for heat exchanger machines.

For thermocoil machines, check out the Breville Bambino.

The Gaggia Classic only has a single boiler, which makes it rather challenging to operate.

The Steam Wand

When it comes to having an espresso machine, you are also going to have to keep in mind what type of beverages you want to make and how much control you want over that.

Espresso machines will either have a steam wand or a frother. Frothers are typically automatic and will aerate the milk to the point of it being foam. This technology is typically used on automatic espresso machines. It’s something that real coffee snobs typically look down upon.

Steam wands, on the other hand, are manual. This allows the user to aerate the milk to a desired texture and temperature. If you know what you’re doing you can create milk that has the right texture for latte art.

The Group Head

The group-head on an espresso machine is where the magic happens. That is where your finely ground coffee gets turned into a beautiful tasting shot of espresso.

A portafilter has a basket that carries the finely ground coffee that then connects to the group-head. The group-head has pressurized water coming from the boiler to brew the coffee into an espresso.

Earlier, the Faema E61 espresso machine was mentioned and how it helped bring espresso into the contemporary era that it finds itself in now.

The group-head that Valente created uses a thermosyphon heating system. What happens is that the heat exchanger heats the water in the boiler. The hot water moves toward the group-head, but it is still rotating, caused by the heat exchanger. The water will heat up the group-head and head back to the boiler. All of this movement causes thermal stability that is kept as long as the machine is up and running.

Being that dual boiler espresso machines have so much to offer, they also provide a more stable group-head heat rather than a heat exchanger since it will most likely have a PID included with it that will allow you to have a set temperature.

Espresso Machine Upkeep

Espresso machines aren’t cheap, and proper upkeep will allow you to use them longer and get the most out of them. There should be daily, every few months, and yearly duties are done to make sure that happens.

Make sure to invest in the proper cleaning products designed specifically for espresso parts.

  • Daily: Make sure you are clearing the group-head as soon as you are done pulling a shot. Purge and wipe off your steam wand as soon as you are done using it. Milk build-up will scale and can close up the holes on your steam wand. At the end of each day, make sure to clean the machine by backflushing the group-head. Backflushing gets out all the coffee grounds from the day.
  • Monthly: The biggest “every few months” maintenance you need to be doing is checking your water quality and water filter. Bad water can ruin an espresso machine.
  • Yearly: The important parts need to be inspected. Any valves or gaskets need to be checked to see how they hold up. Make sure your pump and boiler are doing their job. Also, keep in mind any portafilter baskets or group-head screens that may need to be replaced.

Conclusion

Whether it is an at-home espresso machine or a commercial machine in a coffee shop, these devices are a huge joy to work with, but no small thing to be taken lightly.

A lot of research needs to be done before making a purchase. You have to consider all the variables and how they relate to the espresso you want to make.

Espresso machines have come a long way, and although brewing is becoming more automated, there is still something special about taking the time to dial in a coffee and to consider all the fluctuating details.

My hope is that you appreciate espresso and its history while continuing to learn new ways to make incredible tasting coffee without sacrificing the integrity that this craft has built.

Top Featured Image: Professionelle Siebträgermaschine von FAEMA by Marco Verch under Creative Commons 2.0


FAQ

How do espresso machines create pressure?

Espresso machines create pressure by the pump that they have within the machine. There are two main types of pumps used today, rotary and vibratory. However, manual levers are still used by some retro espresso makers as well as portable devices.

How does a commercial coffee machine work?

Commercial espresso machines are typically ones used for high-volume shops where hundreds to thousands of espresso shots are pulled every day. This means that many of the processes are going to be automatic and set beforehand.

Processes such as water temperature and water pressure are the most important.
Secondary processes could be an espresso machine that has a chronometric, gravimetric, or volumetric feature included in them.

Do espresso machines also make regular coffee?

If you mean coffee from a drip brewer by regular coffee, then no. The closest you could get to that is pulling a very long shot, also known as a “lungo”. However, that drink and a brewed coffee from a drip machine or pour over are rather different.