Sour

Sour: An excessively sharp, biting, and unpleasant taste profile—resembling vinegar or acetic acid—often associated with fermented coffee aromas. This defect can be caused by overripe or fermenting coffee cherries, or by improper fermentation where yeasts and alcohol produce vinegar-like acids. Sour flavors are frequently confused with positive acidity, which is the pleasant, bright, and tangy sensation characteristic of high-quality coffee.