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What is Chlorogenic Acid and What is Its Relationship with Coffee Roasting? The Acidity in Coffee Comes from Chlorogenic Acid

Published: 2026-01-27 Author: FrontStreet Coffee
Last Updated: 2026/01/27, Professional coffee knowledge exchange For more coffee bean information Please follow Coffee Workshop (WeChat public account cafe_style ) FrontStreet Coffee briefly explains what chlorogenic acid is and what is its relationship with coffee roasting? Chlorogenic acid is formed through esterification reaction and dehydration condensation of quinic acid and caffeic acid. This is a reversible reaction. That is, chlorogenic acid can undergo hydrolysis reaction when encountering water and decompose into qu

FrontStreet Coffee: What is Chlorogenic Acid and Its Relationship with Roasting?

Professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat public account: cafe_style)

Chlorogenic acid is formed through an esterification reaction between quinic acid and caffeic acid, resulting in dehydration condensation. This is a reversible reaction. This means that chlorogenic acid can undergo hydrolysis when exposed to water, decomposing back into quinic acid and caffeic acid. Since hydrolysis is an endothermic reaction, the heating process during coffee roasting promotes the decomposition of chlorogenic acid.

Chlorogenic acid is the most abundant organic acid in raw coffee beans and is the main culprit behind coffee's sharp, astringent bitterness. Fortunately, chlorogenic acid is destroyed during the roasting process. More importantly, the degree of chlorogenic acid breakdown is inversely proportional to the roasting speed (the time interval between first crack and dropping the beans before second crack). This means that faster roasting leaves more residual chlorogenic acid, while slower roasting leaves less. This explains why fast-roasted beans taste sharper and more acidic, while slow-roasted beans have smoother flavors.

The Relationship Between Roasting and Quality Acids

In addition to undesirable chlorogenic acid, raw beans also contain numerous quality acids, the most important of which include citric acid, malic acid, acetic acid, phosphoric acid, and quinic acid. Additionally, other organic acids are created during the roasting process as carbohydrates break down. Currently, as many as thirty-four different organic acids have been identified, fifteen of which are volatile.

In principle, quality acids such as citric acid, malic acid, phosphoric acid, and acetic acid reach their highest concentration during medium roasting and decrease with darker roasts.

Organic acids significantly influence coffee flavor. Interestingly, the pleasant, lively fruity acidity in light-roast coffee is the collective expression of over thirty different organic acids. If any particular acid becomes too prominent, it can result in an unpleasant taste.

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