In what condition might you let grinds sit in the portafilter for too long?

Letting grinds sit in the portafilter for too long is often related to temperature variance. When grinds are left in the portafilter for an extended period, they can become affected by the ambient temperature as well as the varying temperature of the portafilter itself. This can alter the extraction process because coffee is sensitive to these temperature fluctuations. If the temperature of the grinds is inconsistent, it can lead to uneven extraction, resulting in flavors that are either over-extracted or under-extracted.

In scenarios where temperature control is key, such as when the portafilter may not have been preheated adequately or when it’s exposed to cooler air could hinder the brewing process. Therefore, avoiding letting the grinds sit too long helps in maintaining a stable temperature, which is crucial for achieving the best flavor profile in your coffee.