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.
Sensorially quinic and caffeic acid have been associated with the increased levels of astringency, bitterness and body commonly seen in darker roasting styles.