Espresso
Channeling
An extraction defect where pressurized water finds a path of least resistance through the coffee puck, over-extracting that narrow channel while under-extracting the surrounding bed. It produces a shot that is simultaneously bitter and sour.
Detaylı
Channeling can be caused by uneven grind distribution, inconsistent tamping, cracks in the puck surface, or an excessively fine grind that forces water to find any available gap. Naked (bottomless) portafilters make channeling visible as uneven streams, spurting, or blonding on one side of the basket. Prevention involves careful puck preparation—WDT, level tamping, and appropriate grind size. Pressure profiling machines can mitigate channeling by starting with a gentle pre-infusion that saturates the puck before ramping to full pressure.