Pre-infusion

Short description:
The initial phase of the espresso extraction process, where water soaks the ground coffee, results in a more even and complete extraction.

Long description:
Pre-infusion is the process where water is briefly allowed to steep in the ground coffee before full pressure extraction. This step improves the uniformity of the extraction by allowing the ground coffee to soak evenly, resulting in a smoother and fuller flavor profile.

Pre-infusion is typically performed in these steps:

1. Setup - After inserting the portafilter into the group head and turning on the extraction, a low water pressure is first applied to the coffee.
2. Absorption - The coffee is evenly moistened and softened, allowing for a more even extraction during the main phase.
3. Main extraction - After pre-infusion, the water pressure is increased to the value needed for full extraction of the espresso.