Understanding Coffee Acidity

Coffee enthusiasts often celebrate the "acidity" in coffee as a positive attribute. Contrary to what some may think, acidity in coffee does not refer to pH. Instead, it's a term used to describe the bright, fruity, or crisp flavours experienced while drinking coffee.

Coffee Acidity

Acidity in coffee

Acidity is one of the key characteristics used by coffee professionals to describe the taste of coffee, alongside body, aroma, sweetness, bitterness, and aftertaste. It's a complex interplay of various acids that are naturally present in coffee beans.

Acids Found Green Coffee

The primary acids found in green coffee beans include chlorogenic, quinic, citric, and malic acids. The specific composition of acids varies based on species, cultivar, origin, growing altitude, and coffee processing method.


Acids Found in Roasted Coffee

During roasting, the acid composition of raw coffee beans changes significantly. Chlorogenic, citric, and malic acids are degraded, while quinic acid increases in concentration due to the breakdown of chlorogenic acid.

Additionally, organic acids such as acetic, formic, lactic, and glycolic acids are formed as a result of the thermal degradation of soluble carbohydrates, primarily simple sugars like sucrose, glucose, and fructose. Therefore, the primary acids in roasted coffee are chlorogenic, quinic, citric, malic, acetic, formic, lactic, glycolic, and phosphoric acids, with tartaric acid occasionally present as well.

Citric Acid is found in Arabica beans grown at higher elevations. Naturally, the same acid is found in citrus fruits, and it is associated with notes of lemon, orange, and grapefruit in coffee. Coffee from East Africa tends to have higher levels of citric acid.

Phosphoric Acid tastes sweeter than most acids. It can turn a sour citrus flavour into a sweeter grapefruit like flavour.

Malic Acid is sometimes associated with hints of stone fruit, like peaches, but it’s more common to taste apple or pear in a coffee that has malic acid.

Chlorogenic Acids (CGAs) are largely responsible for a coffee’s perceived acidity. Compared to other acids, they degrade rapidly during the roasting process, which is why light roasts are described as “bright” more often than dark roasted coffee.

Acetic Acid is the same acid that’s found in vinegar, producing a pleasant sharpness at lower concentrations. However, high quantities of this acid are unpleasant. A coffee with high acetic acid content was probably not properly processed.

Tartaric Acid creates a sour taste at higher quantities. At low concentrations, however, it produces grape-like or winey flavors.

Quinic acid is produced when chlorogenic acid is broken down during roasting. High concentrations of it are common in darkly roasted coffee, and coffee brewed several hours ago but kept warm on a hot plate. It has a bitter and sharp taste.

Factors Influencing Coffee Acidity

Several factors can affect the acidity of coffee:

Origin and Elevation

The soil composition and elevation at which coffee is grown influences its acidity. Beans grown at higher altitudes often have more pronounced acidity.

Coffee Variety

Different varieties of coffee beans can have varying levels of acidity. Arabica beans, for example, are known for their higher acidity compared to Robusta beans. Find detailed information about the difference between Arabica and Robusta  on our blog.

Processing Method

How the coffee beans are processed after harvesting can also impact their acidity. The Washed processing, also known as the wet processing method is known for producing a clean and bright cup with a high level of perceived acidity.


Acidity, which is responsible for a coffee's perceived brightness and citrus flavors, decreases as the roast progresses. The level of roast can alter the acidity, with lighter roasts typically retaining more acidity than darker roasts.

Brewing Method

The way coffee is brewed can change how acidity is perceived. Under-extraction can lead to a sour tasting coffee, which some may confuse with acidity.

Coffee beans contain aromatic substances such as acids, sugars and plant fibres, which are extracted by hot water in a specific order. The acids are extracted first, followed by the sugars and then the fibres (bitter substances).

 If your coffee tastes sour, it is most likely under-extracted. In other words, the water hasn't had enough time to break down the sugar and add slight bitterness to balance the acidity.

There are a number of reasons for this: The grind is too coarse, the water isn't hot enough or the brewing time is too short.

Measuring Acidity in Coffee

While acidity in coffee is more about flavor perception than measurable pH levels, there are methods to measure the acidity of coffee scientifically. The pH level of brewed coffee can be measured using pH meters, and High-Performance Liquid Chromatography (HPLC) can be used to quantify specific acids in coffee beans.

Coffee's average pH ranges from 4.8 to 5.13. pH values vary from 0 to 14, with 0 being the most acidic and 14 being the most alkaline. Water has a pH of 7, which is the neutral point on the pH scale.

Choosing the Right Coffee

For those who enjoy the vibrant flavors that coffee acids brings to coffee, selecting beans known for their bright profiles, such as those from Ethiopia, Kenya or Colombia, can be a good start.

 Conversely, those looking for lower acidity might opt for beans grown at lower altitudes or darker roasted coffees.


Acidity in coffee is a desirable quality that adds complexity to the cup. These acids contribute to the overall flavour profile of the coffee and can produce flavour sensations similar to those found in fruits such as berries, lemons and stone fruits.

Complex and balanced acidity is a key component of high quality coffees. Acidity in coffee is often mistaken for sourness. While sourness is common in coffee, it is mainly caused by light roasted or under-extracted coffee.