Pre-infusion is the act of pre-wetting the bed/capsule of ground coffee before actually commencing the brew. Water is pumped to the coffee for a second or two, then halted for another second or two. After this pause, the water flows again, and continues brewing the shot.
Is this technique new?
Absolutely no! This is commonly used by barista to extract a nice cuppa when using a manual or semi-automatic machine.
For capsules espresso machines like Nespresso, it can also be done. This technique is better known as “skamping” due to the nickname of the user (Skamp) who discovered/introduced this method.
Pre-infusing a Nespresso capsule
To pre-infuse with the Nespresso capsule, pop a capsule in, press the single shot button to start the got water flowing.
As soon as the the water starts flowing, press the single shot button to pause it. It is normal for some coffee to be extracted at this point of time.
The coffee inside the capsule is currently soaked in the hot water. The duration of pre-infusion ranges from 2 seconds to 5 seconds. The pre-infusion duration depends on the Grand Cru (e.g. Appeggio needs approximately 2 seconds of pre-infusion).
After the desired duration of pre-infusion, press the single shot button to continue with the coffee extraction.
How much time for each Grand Cru?
This actually depends on individual tastebuds. It is better to explore and try it out yourself. 2 seconds works well for Appeggio and Crealto. 5 seconds for decaf intenso.