When the word “sour coffee” is said, many people automatically cringe. We imagine an unpleasant, beastly taste that makes our mouths water. In the world of quality coffee drinking, however, the word “acidity” is one of the most sought-after attributes.

Why is this so? Because without acidity, coffee would be boring.

In this article we will look at why it is Specialty coffee is often fruity, the chemistry behind it, and how to distinguish a pleasant juiciness from an unpleasant vinegary taste.

What is acidity in coffee?

In the technical language of baristas and roasters, acidity does not mean that the coffee tastes like lemon juice. Rather, it’s brightness, vibrancy and sparkle. Imagine the difference between plain water and water with a drop of lemon or bubbles. Acidity is what gives coffee its character and enhances its flavor profile.

Even the Specialty Coffee Association (SCA), which sets global standards, lists acidity as one of the key parameters. On their iconic Flavor Wheel ( SCA Coffee Taster’s Taste Wheel), you’ll find an entire section dedicated to sour and fruity notes – from citrus to berry to stone fruit. They’re the reason we say coffee tastes like blueberry or green apple.

No acidity like acidity: chemistry for coffee drinkers

In order to understand why we smell fruit notes on the tongue, we need to look beneath the surface. The green coffee bean is not just a hard, tasteless stone, but a complex biological storehouse full of potential.

From a chemical point of view, the grain forms a fascinating mix where each ingredient plays its part in the resulting flavour profile:

• Carbohydrates (approx. 50 % of dry matter): form the structure of the grain. The key here is sucrose, which caramelises during roasting and breaks down into various organic acids. It is this which gives a good quality specialty coffee its pleasant sweetness.
• Lipids (approx. 16%): coffee oils are the carriers of aroma and texture. They are responsible for the mouthfeel (fullness of the body) and create the crema in espresso.
• Proteins (10-12%): although we don’t smell them directly, they are essential for the Maillard reaction – the browning process that produces hundreds of aromatic substances (notes of nuts, chocolate, bread).

Key Players:Organic Acids

While fats and sugars make up the body and sweetness, organic acids give coffee “life”. Expert sites like Perfect Daily Grind often liken roasting to a dance with these acids – some are broken down by heat, others are transformed.

Here are the most important ones that define the character of your cup:

1. Chlorogenic acids (CGA): coffee contains the most of these powerful antioxidants of all plants. They are crucial, but tricky. During roasting, they quickly break down into quinic and caffeic acids. If the coffee is roasted too dark, it is these broken down components that will cause a bitter and beastly bitterness.
2. Citric acid: It is responsible for the crisp, citrusy freshness and “high notes” in the taste. It is a typical signature of specialty coffee from Kenya and Central America, grown at high altitudes.
3. Malic acid: reminiscent of the taste of green apple, pear or stone fruit. On the tongue, it is softer, sweeter and juicier than citric acid.
4. Phosphoric Acid: This inorganic acid is unique. It gives coffee a “fizz” and sparkly sensation on the tongue, reminiscent of sparkling cola or gooseberries. It is often found in coffees from Kenya due to the composition of the soil there.
5. Acetic acid: It is a double-edged weapon. In small, controlled amounts, it adds a pleasant winey sharpness and complexity to coffee. In large quantities (often with poor fermentation), however, it causes an unpleasant vinegar aftertaste.

Tip from Goriffee: Looking for a coffee with low acidity? Reach for beans from Brazil or India. If you want a fruit bomb, Africa (Ethiopia, Kenya) will be right for you.

Why is some coffee more acidic than others?

Three main factors influence whether your morning cup tastes like dark chocolate or fruit tea:

1. Origin and altitude

Coffee trees grown at higher altitudes ripen more slowly. This allows the beans to develop more complex sugars and acids.

2. Processing method

The processing method fundamentally changes the perception of acidity:

• Wet processing (Washed): usually produces coffee with higher, cleaner acidity.
• Dry processing (Natural): often leads to a sweeter taste with hints of dried fruit and milder acidity.

3. Roasting

This is the key moment. The longer and darker the coffee is roasted, the more the acids break down and the bitterness subsides. At Goriffee, we strive to find the ideal balance to bring out the unique flavour profile of each bean.

How to distinguish between “good” and “bad” acidity?

This is the most common customer concern. How to know if the coffee is spoiled or if it is supposed to taste that way?

• Good acidity (Brightness): it is refreshing, juicy and sweet. After swallowing, you have a pleasant sensation in your mouth, you want to drink again.
• Bad acidity (Sourness): it is sharp, animalistic and “flat”. It is reminiscent of unripe fruit, vinegar or lemon peel. It is often the result of under-extraction.

What should I do if the acidity in my coffee bothers me?

If you prefer more conservative tastes, it doesn’t mean you can’t drink quality coffee. Specialty coffee offers a wide range of tastes.

1. Choose by profile: look for words like chocolate, nuts, caramel in the description.
2. Try our blends: they are often blended to be balanced.
3. Change the preparation: try grinding the coffee more finely or increasing the water temperature to help draw out more sweetness.

So why is acidity in coffee desirable?

Here are the 3 main reasons why it is in demand in specialty coffee:

1. It gives the coffee “life”: without acidity, coffee would taste dull, flat and just bitter. It is the acidity that makes the difference between boring “brown water” and a refreshing drink. It works like in gastronomy – a drop of lemon or vinegar can “light up” the taste of food.
2. Creates fruity notes: what we perceive as the taste of strawberries, oranges or apples in coffee are chemically these organic acids. Without acidity , coffee would not have a complex flavour profile, we would only sense roastiness (ash, smoke) or bitterness.
3. It is a sign of quality: the pleasant, sweet acidity is proof that the coffee grew at high altitude, matured slowly (picked up sugars) and was not burnt to an angle during roasting.

Frequently asked questions about coffee acidity (FAQ)

Is sour coffee bad for the stomach? Not necessarily. Although it doesn’t seem like it, the pH of black coffee is around 5.0. By comparison, orange juice or wine have a significantly lower pH (they are more acidic). Scientific studies available on PubMed (National Library of Medicine) suggest that stomach irritation is often related to substances produced during roasting rather than to the acidity itself. For example, darker roasted coffee may paradoxically be gentler on the stomach because it contains fewer substances that stimulate stomach acid production.

Which coffee has the lowest acidity? Coffees from regions such as Brazil, Mexico or Sumatra are naturally lower in acidity.

How to learn to perceive tastes in coffee? The best way is regular tasting. The ideal is Goriffee coffee subscriptionwhich gives you a regular supply of fresh beans from all over the world direct to your home.