'Acidity’ may be scored by intensity, quality, or both. For ‘intensity’, the SCA and COE forms ask متذوقي القهوة for a numeric rating, but for ‘حموضة’ they ask متذوقي القهوة to rate by quality. According to the COE protocol, negative حموضة might be described as ‘harsh’ or ‘tart’, and positive حموضة might be ‘refined’ or’ snappy’. SCA suggests ‘bright’ and ‘lively’ as attributes for positive حموضة that gives a fresh fruit sensation and ‘sour’ for negative حموضة. The SCA form also specifies that the intensity rating should be in line with what’s expected for coffees from that specific region — in other words, a high- حموضة Kenyan and a low- حموضة Sumatran might still get the same quality score for their حموضة, but the reverse would be unlikely.
Unlike the other organic acids in coffee, acetic acid contributes an aroma as well as the acidic taste. This means that excessively high levels of acetic acid can be very negative in the cup. Small amounts, however, probably contribute to an overall positive حموضة profile.
The sensation of حموضة in coffee is not closely linked to a coffee’s pH. Instead, perceived حموضة is linked to titratable حموضة (N.Z. Rao and M. Fuller, 2018), the ability of the liquid to buffer alkali.
The bitterness of coffee can be experienced as a positive and a negative sensation, in part by how intense it is and possibly, what chemicals are responsible for producing a bitter sensation. A form of positive bitterness might be experienced like the quininic acid in tonic water which relies heavily on the حموضة and sweetness of the beverage to repackage the bitter taste as a positive.