What is "over-extraction" in coffee brewing?

Over-extraction in coffee brewing refers to the scenario where coffee grounds are brewed for too long, resulting in an undesirable bitterness. During the brewing process, water extracts various compounds from the coffee grounds. Ideally, the extraction should occur within a certain time frame to obtain the best flavor profile. When the brewing time exceeds this optimal duration, over-extraction takes place, and the coffee starts to release harsher compounds, including excessive tannins and other bitter elements, leading to a taste that is not enjoyable.

Understanding over-extraction is crucial for baristas and home brewers alike, as it informs the importance of timing in the brewing process. Properly managing extraction times can help in achieving a well-balanced and flavorful cup of coffee.