Say you're learning more about coffee or are reading an espresso recipe, then come across something called "soft infusion" espresso or "gentle pre-infusion" espresso -- well, what does that mean? This way of making espresso is a great method in making sure your coffee is consistent and flavourful.
What is soft infusion espresso?
This type of infusion doesn't go straight to the standard 9 bar brewing pressure. Instead, the espresso machine opts to cover the coffee puck in water at a lower pressure first. Typically between 0.5 and 3 bars, the puck is doused in water for about 2 to 8 seconds before the full-pressure extraction takes place.
There are two kinds of soft infusion systems: mechanical and digital (or programmable). Mechanical gradually increases pressure through a chamber or mechanical valve system, while digital does this through software-controlled pumps and solenoid valves. The latter is capable of more advanced pressure profiling.
What's its purpose?
The first question you might have is: why?
There are a few reasons why soft infusion is the method that many enjoy. A major selling point is the fact that it makes extraction more likely to be consistent. By saturating all of the grounds at a lower pressure before full extraction, the entire puck gets a chance at expanding, creating a more even surface for the extraction to take place on.
In other words, soft infusion reduces channeling. Channeling — as the Specialty Coffee Association explains — occurs when inconsistencies in the coffee puck allow water to flow unevenly, leading to poor extraction. By having the lower pressure water go first in soft infusion, the grounds get to expand equally, and there is less of a chance that the water passes through unevenly.
What does this mean for my coffee?
This all has an impact on your coffee experience--the flavour profile is enhanced because of the consistent extraction and results in a more satisfying cup for yourself.
- Sweetness and body of the coffee are enhanced
- Acidity is smoother
- Bitterness is more controlled
The effect of time on flavour
- 1-2 seconds: incomplete puck saturation, higher risk of channeling, brighter acidity, lighter body
- 3-5 seconds: the optimal time duration. Here, there is balanced sweetness, acidity, and body, with a stable crema
- 8-12+ seconds: early over-extraction, reduced sweetness, increased bitterness, and a thinner crema
What can I do to control soft infusion?
With modern machines, a lot of the time, the user has some control over soft infusion, such as with its time and pressure settings. Different drinks and types of coffee will require different variables, which is where the user (like you!) will be able to have their hand in this part of the process.
Identifying the ideal settings for varying types of roasts, bean origins, as well as flavour profiles is a great way for coffee enthusiasts to be more in tune with their product.
Read and view the full article written by QCS' very own Certified Coffee Expert and Educator, Reza Mehrad:
