The Science Behind Coffee: Why Is Coffee Acidic but Bitter?

If you have done some readings on coffee, you may notice that coffee is actually acidic in nature. You may also notice that there is low-acid coffee meant to counter the acidity in the coffee. 

However, if coffee is acidic, shouldn’t it taste sour? Why is coffee acidic but bitter instead?

Coffee is acidic but bitter because it combines acid and alkaloids. Acidic content should cause coffee to be sour, but alkaloids produce a bitter taste. Roasting and brewing methods could also make coffee much more bitter than acidic.

This article explores why coffee is acidic yet bitter at the same time. We will also consider whether there is a way to reduce acidity or bitterness in coffee.

Is Coffee Acidic?

Coffee is acidic because it contains many organic acids, such as chlorogenic and citric acid. These acids help contribute to a coffee’s unique taste profile, making it taste tangy and tart. Coffee grown in high altitudes and volcanic soils, such as Brazilian, Kenyan, and Ethiopian coffee, tend to be more acidic.

Coffee, on its own, is an acidic drink. If you run coffee on PH tests, chances are the readings will show between 4.85 to 5.10. A PH test measures acidity or alkalinity. Anything under 7 is acidic and above alkali. 

Coffee is usually acidic as it contains many times of organics inside. Some of these acids include:

  • Chrologenic
  • Citric
  • Acetic
  • Formic 
  • Lactic
  • Glycolic acid

These acids may exist in their natural form inside the coffee or may be formed during the roasting or brewing process.

These acids are seen as good things in coffee. This is because their presence helps to create specific tastes for the coffee. Often acidic coffee carries a hint of tartness or tang that may appeal to some drinkers.

Generally, coffees planted in higher altitudes or on volcanic soil tend to show higher acidity. Some of this coffee includes Brazilian, Peruvian, Kenyan, or Ethiopian.

Why Is Coffee Acidic But Bitter?

Coffee is acidic but bitter because of alkaloids, such as caffeine, putrescine, theophylline, or trigonelline. Alkaloids are bitter in taste. The roasting and brewing process may also make the bitter taste in coffee stronger than the acidic taste.

The bitterness in coffee may come from several sources. Together, they combined to make the bitterness strong, to the point that it masks the acidity in coffee. 


Alkaloids are compounds that exist naturally in coffee. Some of the common alkaloids in coffee include:

  • Caffeine
  • Putrescine
  • Theophylline
  • Trigonelline.

Many alkaloids are alkaline in nature, which causes them to taste bitter. Combined, they contributed to the bitter taste of coffee. Caffeine, for example, is alkaline.


When roasting, coffee beans go through what is called the Maillard process. During the process, the sugar molecule inside the coffee is broken down by the heat into reactive carbonyls.

The common observation is that the longer the coffee is roasted, the more bitter they become

They, in turn, react with the amino acid in the coffee to form different compounds, such as melanoidin, that give coffee its signature brownish color. The Maillard reaction also contributes to the flavor of coffee, including bitterness. 


The brewing process may cause coffee to become bitter, particularly if it is not done correctly. Some of the ways you can cause your coffee to become bitter include:

Over brewing: If you let your water steep too long with the grind, you may over-extract the coffee and draw out compounds such as tannins. These make the coffee a lot bitter. 

Wrong Grind Size: If your coffee grinds are too fine for your brewing technique, you may end up with a more bitter coffee. This is because the fine grind size makes it easier to extract the coffee. For example, if you use a Moka Pot to brew Turkish coffee grounds, you may over-extract the coffee.

How To Reduce Acid In Coffee?

You can reduce acidity in coffee by drinking low-acid coffee or brewing using a cold brew method. You can add milk or cream to the coffee to cut into the acidity or drink dark roast coffee instead.

There are several ways to reduce the acidity in coffee. This could be done by:

Drinking Low-acid Coffee: There is such a thing as low-acid coffee. These coffee are often grown in unique soil conditions and then roasted using specific steps to reduce the acidity. Low-acid coffee tends to be easier on the stomach and does not have a tart or tangy taste.

Drink Cold Brew: Coffee tends to be less acidic if they are brewed using cold water. Cold water brew is one common way to reduce acidity in coffee. Some common cold brew methods include ice dripping or immersion brewing.

Add Milk Or Cream: If your coffee is too acidic, add some milk or cream to dilute it. This may dilute the coffee and cut into the sour taste. Milk is only slightly acidic in PH, which means it should help raise its PH level when combined with coffee.

Drink Dark Roasts: If your palate can handle dark roasts, they would be a good option for drinking less acidic coffee. Longer roasting tends to result in more of the acidic compounds in the coffee broken down, giving you a less acidic coffee overall.

How To Reduce Bitterness In Coffee?

You can reduce bitterness in coffee by using high-quality beans and brewing your coffee properly. You can also drink lighter roasts and add milk, cream, or sweeteners to cut into the bitterness.

Unlike acidity, it may be easier to remove the bitterness in coffee. These could be done by:

Use High-Quality Beans: High-quality coffee beans are carefully processed, selected, and roasted to the right level. This means the coffee would have lesser chances of being over-roasted, burnt, or not ground down to the right size. These factors can easily cause coffee to be much better than it should be.

Brew Your Coffee Properly: Many coffees become much more bitter than they should be because they are wrongly brewed. Ensure you grind your coffee beans to the right size before brewing them using the suitable brewing method. Check the water temperature and brewing time to ensure you execute a good brewing.

Drink Lighter Roasts: Darker roasts spend more time in the roaster, which means they develop more smoke and bitterness in the coffee. If you want something less bitter, consider trying out lighter roasts.

Add Flavorings: Finally, you can save your bitter cup of coffee by adding flavorings to cut into the bitterness. Milk and cream introduce some fat into the coffee, making it creamier and less bitter. 

Sugar or sweeteners such as Stevia take away bitterness by masking it with sweetness. You can add other flavorings, such as vanilla cream, or spices, such as cinnamon or cardamom.

Final Thoughts

While acidity and bitterness are natural components of coffee, there are ways to reduce these qualities. For people who experience acid reflux or heartburn, lower-acid coffee alternatives are available.

Choosing the right roast level and brewing method can help reduce bitterness while enhancing the natural flavors of coffee.

Whether you prefer a bold, dark roast or a milder, fruity flavor, understanding the balance of acidity and bitterness is key to enjoying a delicious cup of coffee.

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