9; 15 or 19 bar - what is the ideal pressure in a coffee machine?

The role of pressure in espresso extraction

Pressure plays a key role in coffee preparation as it affects the rate at which water flows through the ground beans. With its correct value, it produces the creamy consistency of espresso and more importantly the thick crema itself.

Incorrect pressure can lead to under- or over-extracted espresso, which affects the quality and taste of the final product. At pressures lower than 9 bar (taking this value as a notional limit), the coffee becomesmore watery and the crema diminishes.

The preparation of the coffee bud or the right temperature also plays a big role in espresso extraction. That's why I recommend watching the video on the preparation itself.

Influencing the espresso by increasing the pressure

If you have the opportunity, try the following test.
If you give the same batch of coffee on a fixed grind coarseness setting and extract at 7; 8; 9; 10 and 11 bars, you can observe that as thepressure increases, different amounts of liquid will pass through the puck. Assuming, of course, that the production time had thesame set time for all , say 30 seconds.

Theflow increases, until you cross the 9 bar threshold. Higher pressure starts to compress the coffee bud, making the water flow more challenging. Not only does the flow rate start to decrease again, but the espresso itself is too strong and thickens.

So the imaginary peak pressure is 9 bar. Let's zoom in on this in the next point.

Why is 9 bar considered a standard value?

The ideal level of pressure passing through the coffee beans should be around 7-11 bar of pressure, although some espresso machines will be able to reach higher values.

So the answer to the question is this - not only because 9bar is found in the vast majority of coffee machines, but also because this pressure is sufficient to optimally extract all the flavours and oils contained in the coffee beans.

Is 15 or 19 bar even worth it?

Neither value is appropriate to the taste of the final product. Realistically, if we keep increasing the pressure, will our espresso continue to improve? The answer is: it won't. Such high pressures can cause increased bitterness or acidity.

Rather, this has given rise toa marketing strategy for cheaper coffee machines where a machine with more bars is better than one with less pressure.

In this case, the relationship between pressure and waterflow is comparable to a Gaussian curve. Initially, theflow rate increases with increasing pressure until a point where, from a certain value,it starts to decrease again. This maximum flow is just at that 9bar.

Personally, I can imagine higher bar values when experimenting with extraction. Otherwise it makes very little sense, unless you are the one doing the potion experiments.

Consistent or Maximum Pressure

Consistent pressure during espresso extraction contributes to consistent results. Consistent pressure ensures that each cup of espresso has a similar taste and quality, which is important in general, not just in a professional setting.

The maximum pressure that coffee machines are capable of achieving may look nice on paper, but maintaining a consistent pressure is much more essential to espresso preparation.

Rotary vs. vibrating pump

Thequality and progression of pushing water through the ground coffee beans is greatly affected by the type of pump chosen.

Dimensionally smaller and cheaper vibrating pump is noisy and has a shorter lifetime. It is used exclusively in small coffee machines with a reservoir. Once started, water pressure builds gradually and how well you grind and tamp the coffee will determine the final water pressure.

In contrast, the significantly larger and more expensive rotary pump will not punish you for poorly prepared coffee beans. The water pressure doesnot build up gradually, but immediately after starting is constant regardless of the quality of the prepared impediment to the pushing water. These quiet pumps with long life find their application in large coffee machines with fixed water connections.

The best coffee machines in the "price/performance" ratio in terms of pressure consistency

It's worth considering whether it makes sense to buy a pump coffee machine rather than a manual lever machine, as they represent thebest price/performance ratio in this respect.
If you're looking for a coffee machine that provides consistent pressure at a fairly reasonable price for their performance, definitely reach for the La Pavoni brand or the Flair brand.
More specifically, you won't go wrong by buying manual lever models from La Pavoni or Flair, specifically the Flair 58 or the La Pavoni Europiccola Lusso.

Find out how to properly make espresso in a Flair coffee maker.

Reach for the 9 bar

To sound some clear and concise answer to the article's title - pressure ofnine barrels is really the ideal choice. If you have the opportunity to "play around" with the pressure of the coffee machine, then (as mentioned) even values between 7-11 bars may besuitable for you . It depends on your preference for coffee taste and consistency.

After all, you can also try the so-called Turbo shot, which requires only 6 bars of pressure and 15 seconds of extraction.