Brewing Basics
Agitation
Any physical disturbance applied to the coffee-water mixture during brewing, such as stirring, swirling, or turbulent pouring. Agitation accelerates extraction by refreshing the solvent around each particle.
In Depth
Gentle agitation breaks up clumps and redistributes fines, promoting even extraction across the entire coffee bed. Excessive agitation, however, can dislodge fines that clog a paper filter or create astringent over-extraction at the particle surface. Competition baristas carefully calibrate the number and intensity of stirs or swirls as a key recipe variable.