Musty Notes

Musty notes are a significant quality defect in the coffee industry. When a coffee is described as musty, it carries an aroma or flavor reminiscent of a damp basement, old books, or mold. This is a clear indicator that the coffee has been compromised, either through poor environmental conditions during storage or through contamination during the post-harvest processing phase.

What is musty coffee? The mustiness is usually the result of fungal growth or the absorption of moisture in an environment that lacks proper ventilation. Coffee is highly hygroscopic, meaning it readily absorbs moisture and odors from its surroundings. If green coffee is stored in humid, non-climate-controlled warehouses, or if it is packed in bags that do not provide an adequate oxygen barrier, it can quickly develop musty characteristics. In some cases, this is also linked to 'aged' coffee that has been stored for too many years without proper protection.

Why is this a problem? Musty notes are not just a matter of preference; they are a sign of a compromised product. Mold growth can produce mycotoxins, and even in cases where the coffee is safe to drink, the musty flavor is so pervasive that it completely masks the inherent quality of the bean. A musty cup is flat, unpleasant, and lacks the clarity and sweetness that define specialty coffee. It is a defect that professional cuppers look for immediately, as it is a disqualifying factor in most quality grading systems.

In practice, identifying musty notes is essential for both roasters and consumers. If you are a consumer, ensure your coffee is stored in a cool, dry place and consumed within a reasonable timeframe. If you are a roaster, rigorous quality control at the point of import is vital to ensure that no musty lots enter your production. If you ever encounter a cup that smells like a damp cellar, it is best to discard it, as the musty flavor is a clear sign that the coffee has failed to meet the standards of specialty quality.