What is acidity in coffee?

In the context of coffee tasting, 'acidity' is often the most misunderstood term. To the average consumer, the word might sound negative, implying something harsh or stomach-churning. However, for coffee professionals, acidity is a positive attribute that provides the 'sparkle' or 'brightness' in a cup. It is the sensation that makes a coffee feel alive, similar to the crispness of a fresh apple or the tang of a citrus fruit.

Acidity is primarily influenced by the coffee's origin and the altitude at which it was grown. Coffees grown at higher altitudes tend to mature more slowly, which allows for a greater development of organic acids, such as citric, malic, and tartaric acids. These acids are what give high-quality beans their complex, wine-like, or fruity profiles. When you taste a coffee and describe it as 'bright' or 'tangy,' you are experiencing these natural acids.

It is crucial to distinguish between pleasant acidity and unpleasant sourness. Sourness is typically a sign of under-extraction, where the coffee has not been brewed long enough or with the right water temperature to balance the acids with the sugars and bitter compounds. A well-balanced cup will have acidity that is integrated with sweetness and body, creating a harmonious experience. If the acidity is sharp, biting, or overwhelming, it may indicate that the roast level is too light or the brewing parameters need adjustment.

In practice, learning to identify acidity is a key step in developing your palate. During a cupping session, tasters look for the intensity and quality of the acidity. Is it sharp like a lemon, or soft like a peach? By paying attention to where you feel the sensation on your tongue—usually along the sides—you can begin to appreciate how acidity contributes to the overall structure of your coffee. Understanding this term allows you to better communicate your preferences and choose coffees that align with your taste.