Which Acid Is Present in Coffee? A Detailed Look

December 12, 2025 •

4 min read

Coffee beans, before roasting, can be up to 11% acid by dried weight, with chlorogenic acids being the most common. However, the specific acids that end up in your cup depend on a variety of factors, including the type of bean, its origin, and the roast level. The balance and presence of these various acids give coffee its signature bright, tangy, or fruity notes.

Quick Summary

Several acids contribute to coffee's flavor, with chlorogenic acids being the most abundant in green beans and evolving during roasting. Factors like bean origin, roast level, and brewing method influence the final acid profile, which includes citric, malic, and quinic acids. The right balance of these compounds determines the coffee's overall taste and aroma.

Key Points

Chlorogenic acids are key: These are the most common acids in green coffee beans but break down during roasting, influencing bitterness.
Citric and malic acids offer fruity notes: Found in higher concentrations in high-altitude, lighter-roasted coffees, these create citrus and apple-like flavors.
Quinic acid increases with roasting: Formed from the breakdown of chlorogenic acids, this compound contributes to the bitterness of darker roasts and stale coffee.
Phosphoric acid creates a sparkling sensation: This inorganic acid enhances the sweetness and fruitiness in certain high-quality coffees, like those from Kenya.
Roast level is a major factor: Lighter roasts retain more bright acids, while darker roasts produce more bitter compounds.
Brewing method affects perception: Techniques like cold brewing significantly reduce acidity, while pour-overs can accentuate it.
Acidity perception is complex: The overall flavor experience is due to the balance of multiple compounds, not just one acid.

The Primary Acids in Coffee

Chlorogenic Acids

Chlorogenic acids (CGAs) are a family of esters that are the most dominant acids in green, unroasted coffee beans. These acids are largely responsible for the bitter and astringent flavors often associated with coffee. During the roasting process, CGAs break down, and this chemical transformation is crucial for developing the final flavor profile. Lighter roasts retain more of their original CGA content, contributing to a more distinct acidity, while darker roasts have significantly less due to heat degradation.

Citric Acid

This is the acid most commonly associated with bright, citrusy flavors, such as lemon, orange, or grapefruit. It is naturally present in high quantities in coffee grown at high altitudes, particularly in African and Central American varieties. Similar to CGAs, citric acid content diminishes during roasting, which is why it is more prominent in lighter roasts.

Malic Acid

Malic acid contributes a pleasant, crisp, and tart sensation, often reminiscent of green apples or pears. It's another organic acid that plays a significant role in the overall fruitiness of a brewed coffee's flavor profile. Like citric acid, malic acid levels are highest in lighter roasts and decrease as roasting progresses.

Quinic Acid

Quinic acid is an organic acid formed during the roasting process as chlorogenic acids break down. It is responsible for the bitterness and astringency that is characteristic of darker roasts and coffee that has been left to sit for too long. In moderate amounts, it can add to a coffee's complexity, but an excess can be unpleasant.

Acetic Acid

Most recognized as the main component of vinegar, acetic acid in coffee can contribute a tangy, wine-like, or sharp flavor in small, controlled amounts. It is a byproduct of fermentation during coffee processing and the roasting process. When present in too high a concentration, it can produce an undesirable sour or fermented taste.

Phosphoric Acid

This inorganic acid, often introduced during cultivation through fertilizers, provides a unique and desirable 'sparkling' quality. It can heighten the perception of sweetness and fruitiness, with notes resembling tropical fruits like grapefruit or mango. Phosphoric acid is particularly noticeable in high-quality Kenyan coffees.

Factors Influencing Coffee Acidity

Bean Type and Origin: Arabica beans are generally more acidic and flavorful than Robusta beans. High-altitude growing regions, such as those in Ethiopia or Kenya, often produce beans with brighter, more pronounced acidity due to cooler temperatures slowing bean development.
Roasting Process: Roasting is the most significant factor affecting acidity. Lighter roasts preserve more of the delicate organic acids like citric and malic, resulting in a brighter, more vibrant cup. Conversely, darker roasts break down these acids, replacing them with bitter compounds like quinic acid, leading to a flatter, less acidic flavor.
Brewing Method: Different brewing techniques extract acids at varying rates. Cold brewing, with its long, low-temperature extraction, significantly reduces acidity compared to hot brewing methods. Pour-over methods tend to highlight clarity and brightness, while a French press typically yields a fuller, less acidic cup. The grind size and water temperature also play a role, with a finer grind and hotter water extracting more acids.
Processing Method: How the coffee cherry is processed after harvest also affects the final acid profile. Washed (wet-processed) coffees generally have higher acidity, while natural (dry-processed) coffees tend to be sweeter and fruitier, with lower acidity. Extended or experimental fermentation methods can increase the presence of certain acids, such as acetic acid, adding unique flavor characteristics.

Comparison of Acids and Their Flavor Contributions


Acid Name	Naturally Found In	Flavor Profile	Affected By Roasting	Common In
Chlorogenic Acids (CGAs)	Green coffee beans	Astringent, bitter (in excess)	Significantly decreases	Robusta beans, lighter roasts
Citric Acid	High-altitude coffee	Bright, citrus, lemon, orange	Decreases	African, Latin American coffees
Malic Acid	High-altitude coffee	Tart, crisp, green apple, pear	Decreases	Central American, Kenyan coffees
Quinic Acid	Post-roast product	Bitter, astringent	Significantly increases	Darker roasts, aged coffee
Acetic Acid	Fermentation process	Tangy, wine-like, vinegar	Varies (formed during processing/roasting)	Fermented coffees
Phosphoric Acid	Inorganic (from soil/fertilizer)	Sparkling, bright, tropical fruit	Increases during roasting	Kenyan coffees, high-quality beans

The Complexity of Coffee Acidity Perception

While specific acids are responsible for certain taste notes, the perceived acidity of a cup of coffee is much more complex than simply the concentration of individual acids. A study published in a journal accessed via the National Institutes of Health indicates that, for many acids, their concentration in brewed coffee is below the human sensory detection threshold. Only citric acid was consistently detectable in concentrations above the average levels found in brewed coffee. This suggests that the interplay and balance of various compounds, rather than a single dominant acid, create the overall perception of acidity. It is this synergy that makes coffee tasting such a nuanced and rewarding experience.

Conclusion

Numerous acids contribute to the complex and nuanced flavor profile of coffee, with chlorogenic acids being the most abundant in green beans. However, the final mix of acids in your cup is a result of a complex interplay of factors, including bean origin, processing methods, roast level, and brewing techniques. From the bright, citrusy notes of citric acid in a light roast to the deep bitterness of quinic acid in a dark roast, understanding which acid is present in coffee allows for a deeper appreciation of its flavors. Whether you prefer a sparkling, vibrant cup or a smoother, low-acid brew, adjusting your bean choice, roast level, and brewing method gives you the power to control your coffee's final taste. By focusing on these elements, you can tailor your coffee experience to your exact preference.

Frequently Asked Questions

The primary group of acids in unroasted, green coffee beans is called chlorogenic acid (CGA). These make up a significant portion of the bean's dried weight before they are broken down during roasting.

Roasting significantly alters the acid composition. As beans are roasted, heat breaks down chlorogenic, citric, and malic acids. Lighter roasts retain more of these bright, fruity acids, while darker roasts convert them into bitter compounds like quinic acid.

Typically, Arabica coffee beans grown at high altitudes in regions like Ethiopia or Kenya are more acidic. These coffees are often prepared with a light roast to preserve their vibrant, fruity, and floral notes.

Yes, cold brewing significantly reduces the acidity of coffee. The lower temperature and longer extraction time result in fewer acidic compounds being dissolved into the final brew, creating a smoother, less acidic cup.

To reduce acidity, you can choose a darker roast, use a brewing method like cold brewing, or opt for beans grown at lower altitudes. Adding milk or a pinch of baking soda can also help neutralize the acids in your final cup.

The distinct citrus flavor in coffee, which can be reminiscent of lemons, oranges, or grapefruit, comes primarily from citric acid. This acid is naturally present in beans, especially those from high-altitude farms.

All coffee is naturally acidic, with an average pH between 4.5 and 5.1, making it mildly acidic on the pH scale. While some coffees are much brighter or tangier than others, none are perfectly pH neutral.