What is a "washed" defect?

In the context of coffee grading, a "washed" defect is not a single specific error, but rather a category of flaws that can arise during the wet-processing method. The washed process involves removing the fruit skin and mucilage before drying, which is designed to produce a clean, bright cup profile. However, if the process is mismanaged, it can introduce distinct defects that compromise the final quality.

One of the most common defects associated with this method is the "quaker." These are underripe beans that fail to develop proper sugars during roasting, resulting in a pale, khaki appearance and a distinct, unpleasant peanut-like aroma. While quakers can appear in any process, they are often more noticeable in washed coffees because the washing channels are supposed to float away low-density, underripe cherries. When they persist, it suggests a failure in the initial sorting or harvesting stage.

Other defects include "full sour" or "fermented" beans, which often result from improper fermentation tank sanitation or leaving beans in the water for too long. These beans can appear yellowish or wrinkled and impart harsh, vinegary, or rotten flavors to the entire batch. Because washed coffee is prized for its clarity and acidity, even a small number of these primary defects can significantly lower the grade of a lot.

In practice, coffee grading protocols—such as those established by the Specialty Coffee Association—require a rigorous inspection of a 300-gram sample to count these physical defects. For a coffee to be considered specialty grade, it must have a very low count of these primary and secondary defects. For the roaster and the consumer, identifying these defects is essential because they directly correlate to the sensory experience, turning a potentially vibrant, clean cup into one marred by off-flavors.