Welcome back to this third and final issue of organic acids. In the last issue we briefly discussed the role of quinic, caffeic, and citric acid and its role in coffee’s flavor. This time we will explore acetic and malic acid and see how these seemingly simple acids play a major role in coffee’s complex flavor profile.
Quinic acid along with citric and malic represent a significant portion of coffee's total acid content. During roasting quinic acid progressively increases as the levels of chlorogenic acid decrease, suggesting that its formation results from the cleavage of the chlorogenic acid moiety.
Discovered in 1932, chlorogenic acids (CGA) represent a large family of esterified compounds present in green and roasted coffee. During roasting, CGA's slowly decompose to form caffeic and quinic acid with about 50% of the original CGA being destroyed in a medium roast.
Although arabica and robusta coffee may appear similar appearance - there are a number of differences that significantly differentiate these two popular species of coffee. The following list points out a few basic differences.