Is the Acidity in Specialty Coffee Called Coffee Acidity? What is the Acidity of Coffee and Is There Scientific Evidence?

When you taste a coffee with good acidity, you might find it difficult to describe what you're experiencing—especially if you're not familiar with coffee terminology. At FrontStreet Coffee, whenever we cup new beans, the roasters patiently explain to us about the acidity in coffee, its flavor profile, and what type of acid it contains.

When we first started cupping and drinking coffee, we couldn't distinguish the specific acids in coffee—such as malic acid, citric acid, tartaric acid, or the acidity found in cranberries. Distinguishing between these different types of coffee acidity is truly challenging.

I once found it most difficult to decipher "flavor profiles" and the "flavor wheel." To me, they all tasted like coffee. Of course, some were more acidic than others, and some were more bitter, but they were still coffee. Today, FrontStreet Coffee will discuss coffee acidity.

Coffee Acidity

Acid is a chemical substance characterized by a sour taste. In fact, the word "acid" in Latin literally means "sour." Acidic aqueous solutions have a pH value less than 7, with lower pH values indicating higher acidity.

Acids are natural products found in many foods, such as lemons, vinegar, yogurt, and even coffee. Coffee alone contains hundreds of different acidic compounds, from familiar ones like citric acid to more obscure ones like 4-monocaffeoylquinic acid. FrontStreet Coffee will only discuss the main acids that affect taste.

Citric Acid

As the name suggests, citric acid is found in high concentrations in citrus fruits. In fact, it can account for up to 8% of the dry weight of these foods. It is undoubtedly the most common acid in all fruits and vegetables and one of the easiest to identify.

Malic Acid

The taste of malic acid is often associated with green apples (after all, it comes from the Latin word "malum," meaning "apple"). You'll find the purest form of malic acid in rhubarb, which constitutes the main flavor of rhubarb.

In the culinary world, malic acid is often associated with limes, but it's easier to think of it as an "unripe fruit flavor." The concentration of this acid typically decreases as fruit ripens, which is why any green food like green grapes, kiwis, or currants would be classified this way.

Tartaric Acid

Tartaric acid is typically associated with grapes due to its high concentration in the fruit. However, this isn't the only place you can find it. Its salt, potassium bitartrate (commonly known as cream of tartar), is naturally produced during winemaking and often used as a leavening agent in food preparation.

In terms of taste, the most notable characteristic of tartaric acid is its mouthfeel. It causes a significant amount of mouth-watering sensation and leaves an astringent aftertaste. In fact, it's one of the main ingredients in "super sour" candies and gobstoppers.

Acetic Acid (also known as Ethanoic Acid)

Acetic acid is special. Besides having a very characteristic unpleasant taste, it also has a pungent, unpleasant odor. At lower concentrations, this gives it a pleasant sharpness or lime-like taste, but at higher concentrations, its taste and smell are like fermentation.

This trendy taste and smell, especially when paired with other flavors (especially sugar), can produce wine or champagne-like qualities.

pH Value and Coffee Acidity

The simplest way to understand coffee acidity is to treat it as an abstract concept. "Orange acidity" doesn't mean your coffee tastes like oranges. Its true meaning is closer to "it's sour like an orange."

If you consider this explanation, tasting notes suddenly start to make more sense. Since blueberries have a lower acidity than lemons, coffee with "blueberry acidity" would undoubtedly be less acidic than coffee with "lemon acidity." Makes sense, right?

Within the pH range, some fruits have similar pH values despite tasting completely different. Take apples and oranges, for example. So how does this work?

In the case of apples and oranges, the primary acids in each fruit are different. Green apples are primarily composed of malic acid, while oranges are full of citric acid.

Imagine a lovely, bright, light-roast African coffee. When brewed, its pH reads 4.6, so we're looking at grapes, peaches, plums, pineapples, etc. Then you'll notice it leaves a tartaric acid astringent sensation in your mouth. You could define this as "grape acidity" or anything from the sour stone fruit family (for example, sour cherries, plums, etc.). This combination of grape acidity and the fermented taste of acetic acid might even give you a wine-like acidity.

Similarly, low-pH citrus flavors can be identified as "lemon acidity," while higher pH values might be closer to orange. More malic acid flavors with lower pH values could be lime, while higher pH values could be categorized as rhubarb, green apple, or even grapefruit. Once you understand all of this, cupping and understanding coffee acidity becomes much easier.

Improving Your Palate

It's always good to practice your skills by tasting various flavors. Nothing improves your perception of coffee acidity more than tasting various acidic foods!

After clearly understanding the taste of pure acids, move on to some actual foods. Prepare a large plate of fruits, vinegars, and even wines, then categorize them based on the acidity you taste in them.

The thing about cupping is that once mastered, it can both help you understand coffee and make drinking coffee more enjoyable. While acidity characteristics may seem daunting, once you know what you're looking for, they're actually quite easy to distinguish. Before you know it, you'll become an acidity expert.

Important Notice :

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