Quinic Acid in Coffee
Last updated
Last updated
The change in quinic acid content in coffee beans compared to roasted coffee
Acid Quinic
Quinic acid along with citric acid and malic acid make up significantly of the total acid content of pure coffee. During the roasting process, quinic acid gradually increases while the chlorogenic concentration decreases, which indicates that quinic acid forms due to chlorogenic acid cleavage.
The concentration of quinic acid reaches its maximum at the French (dark) roasting level then gradually decreases as the roasting process continues. Figures on the actual temperature when this happens have not been published and vary depending on the environmental conditions in each roaster.
Acid content in green coffee beans and roasted coffee
As seen in the Table below, quinic acid has a lower concentration than the other acids found in coffee. After roasting quinic acid, the concentration is approximately double due to the breakdown of chlorogenic acid (CQA) present in green coffee beans. Since CQA concentrations can vary between coffee varieties and the maturity level of coffee plants, this is an important factor when comparing.
Advanced roasting breaks down CQA and quinic acid to produce a number of secondary substances such as phenol, catechols, hydrogen quinone, pyrogallol and diphenol which are considered aromatic precursors of coffee.
Sour coffee goes during cooling
Quinic acid is associated with increased sour taste perception of pure brewed coffee when cooled. This is most evident when the coffee is stored in a jar above the heating plate where the temperature can exceed 80 degrees Celsius. This effect is also commonly seen during cupping when the cup of coffee cools down and the sour taste is felt.
Nguồn: Coffeechemistry.
