Chlorogenic acid
Major antioxidant in green coffee (5-12% dry weight), partly degraded during roasting. Precursor of acidity and caramel aromas.
Background & Context
Chlorogenic acids (CGAs) are a family of ester compounds formed from hydroxycinnamic acids (primarily caffeic acid) and quinic acid. They are the most abundant polyphenols in coffee — comprising 6–10% of green coffee dry weight in Arabica and up to 14% in Robusta — and one of the primary sources of coffee's antioxidant activity. During roasting, CGAs undergo complex thermal degradation: they break down into caffeic acid, quinic acid, and lactone derivatives (chlorogenic acid lactones). At higher roast temperatures, these lactones further degrade into bitter phenylindane compounds — which are significant contributors to the harsh bitterness of dark roasted coffee. The health significance of CGAs has been the subject of considerable research: multiple epidemiological studies (including the Harvard T.H. Chan School of Public Health cohort studies) associate regular coffee consumption — including CGA intake — with reduced risk of type 2 diabetes, liver disease, and cardiovascular events. Light roasted coffees retain significantly more CGAs than dark roasts, which may partially explain their different health profiles. A 200ml cup of light roast filter coffee contains approximately 150–250mg of CGAs; the same volume of dark roast contains 50–100mg.
Practical Use
For health-conscious coffee drinkers, light roast filter coffee maximises CGA intake compared to dark roast or espresso (which uses smaller volumes). Unfiltered coffee (French press) retains more diterpenes (cafestol, kahweol — with independent effects on LDL cholesterol) but similar or slightly lower CGAs than filtered. The antioxidant marketing of coffee products should be viewed critically — the bioavailability of coffee CGAs in the human gut is approximately 15–25%, meaning absorbed dose is a fraction of consumed dose.
Related Terms
Related terms: Coffee polyphenols — the broader family including CGAs. Maillard reaction — occurs alongside CGA degradation during roasting. Bitterness — CGA degradation products (phenylindanes) contribute. Light roast — highest CGA retention.