Chlorogenic Acid in coffee
Qualitatively speaking, quinic and caffeic acids have been related to the higher degrees of astringency, bitterness, and body in darker roasting methods.
Selected composition for raw coffee (%):
In Arabica and Robusta, coffee contains the highest percentage of chlorogenic Acid of any species in the plant kingdom, at 6-10 percent dry weight.
Changes in climatic conditions, stress on the plant, and insect infestation are among the causes that cause CGA formation. Robusta, cultivated under more challenging circumstances, has approximately twice as much CGA than arabica.
Also, the synthesis of CGA and caffeine are tightly related, such that when CGA concentrations grow, so do caffeine concentrations.
In actuality, there are over a dozen isomers of chlorogenic Acid, each with different sensory properties. CGA-3 predominates in coffee with mono, di, and feruloyl quinic acids in different amounts.
According to recent research, the “di-CGA” version of the Acid may be responsible for the bitter/metallic flavor notes seen in certain coffees. In the case of robusta, which has more significant amounts of di-CGA and a harsher taste profile, this may very well be the case.
|3,4-dicaffeoylquinic acid (di-CQA)|
There are 200 to 550mg per cup (6oz) of coffee, significantly surpassing the antioxidants found in green tea. As a result, coffee tends to be richer in simple phenolics than tea, whereas tea tends to have more catechins.