What is a common characteristic of under-extracted espresso?

A common characteristic of under-extracted espresso is that it tends to be watery and sour. This occurs because under-extraction happens when the water passes through the coffee grounds too quickly or at too low a temperature, preventing the gasses and flavors from being fully developed. As a result, the espresso lacks body and depth, leading to a thin texture that often presents sour notes rather than the balanced flavors expected from properly extracted coffee.

The creamy layer, known as crema, may be less pronounced because the extraction process was insufficient to create that rich experience. This understanding of extraction helps baristas adjust variables like grind size, water temperature, and extraction time to achieve the desired flavor profile in espresso.