Acidity (coffee)
Bright sensation perceived on the sides of the tongue, distinct from sourness. Coffee acidity can be phosphoric (Kenya), malic (apple, Honduras), citric (citrus, Ethiopia) or tartaric.
Why is acidity a marker of quality in specialty coffee?
Acidity in coffee is one of the most misunderstood attributes for casual drinkers, yet it is the backbone of quality in the specialty world. It is not the same as sourness, sourness signals under-extraction or defects, while acidity refers to the bright, lively sensation produced by organic acids naturally present in the coffee cherry. The main acids found in specialty Arabica are citric acid (citrus notes, highest in washed Ethiopian coffees), malic acid (green apple, characteristic of Honduran and Guatemalan lots), phosphoric acid (clean, sharp brightness, the signature of Kenyan SL28 and SL34), and tartaric acid (rare, associated with some Ethiopian naturals). Chlorogenic acids, which make up 6-10% of dry green coffee weight, degrade during roasting into quinic acids, contributing to the perception of bitterness in darker roasts. Altitude and varietal genetics are the two strongest predictors of acidity intensity: cooler temperatures slow cherry ripening, allowing a higher concentration of organic acids to develop in the bean. In SCA cupping, acidity is scored from 0 to 10 for both quality (type of acidity, is it pleasant?) and intensity.
How do you recognise and brew for acidity?
When evaluating a coffee for acidity, look for the term on the roaster's tasting notes, 'bright', 'lively', 'citric', or 'malic' all signal positive acidity. To bring out acidity in brewing, use a higher water temperature (93-96°C) and a medium-fine grind. Washed Ethiopian coffees (Yirgacheffe, Guji) and Kenyan lots consistently display the most pronounced and celebrated acidity profiles. If a coffee tastes sour rather than bright, check your extraction variables: the problem is usually a grind too coarse or a temperature too low, not the coffee itself.
Related Terms
Related terms: SCA score, where acidity is one of 10 evaluated attributes. Chlorogenic acid, the main acid group in green coffee. Ethiopia, benchmark origin for citric acidity. Kenya, benchmark for phosphoric acidity. Extraction yield, low EY produces sourness, not true acidity.