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Are Specialty Coffee Beans Better Bitter or Sour? Characteristics, Mouthfeel and Flavor of Dark Roast Coffee Beans

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, Today's article is quite long, so you might need to read it patiently. (Excited) Come on, Arthur! Let's go downstairs for a cup of coffee! (Shakes head) No, coffee is bitter! You go first, I want to drink milk tea! This conversation was something I could hear almost every day in my former office. Although everyone eventually went their separate ways, whenever I recall those times, my heart still feels warm.

Today's article is quite long, so I ask for your patience to read through it.

"(Excited) Come on Arthur! Let's go grab a cup of coffee!"

"(Robot hand refuses) NO, coffee is bitter! You drink it, I'll drink milk tea!"

This conversation happened almost every day in my former office.

Although we've all gone our separate ways since then, I still feel warm inside whenever I think about those moments.

How many of you have had similar colleagues? Please raise your hand.

Before delving deep into coffee, I also went through a period when I would equate coffee with "bitterness."

OK, since we're talking about bitterness, let's discuss why coffee is considered bitter.

Perhaps it's because our introduction to coffee almost always starts with instant coffee. Due to the processing techniques of instant coffee, we mistakenly believe that "all coffee should taste like instant coffee, and all are bitter."

What Causes Coffee Bitterness?

The bitterness in coffee is caused by caffeine, but caffeine actually only accounts for 10% of the bitter components. The caffeine content in coffee beans is not affected by the degree of roasting, and even decaffeinated coffee has bitterness. Therefore, we can confirm that caffeine is not the sole cause of bitterness.

So, some might ask: Can we control the degree of bitterness?

Of course we can.

We can control bitterness by changing the type of coffee beans, the degree of roasting, and the roasting method. Additionally, changing the extraction method can also control coffee bitterness to some extent.

The Fascinating World of Coffee

Actually, before I delved deep into coffee, what impressed me about coffee was how fun, interesting, and ritualistic it is~

The dry aroma after grinding coffee beans, the wet aroma during blooming, the flavors presented at different temperatures, the long-lasting aftertaste, and even the texture and feel of different brewing equipment, etc.

But what's even more interesting is that coffee can be completely different depending on the depth of roasting, the mood of the brewer, and different brewing techniques.

I think this might be the reason I fell into the coffee trap—the charm of coffee!!

Is Sour Coffee Spoiled?

Coffee is originally an agricultural product, and most coffees have fruit acidity.

When specialty coffee is properly light-roasted, it will have special acidic aromas.

"Acidity" is quite popular among coffee enthusiasts.

Light roasting can express acidic flavors, while dark roasting can highlight bitter flavors.

Extended Reading: Coffee Acidity

Coffee beans contain more than 30 organic acids, some of which provide "sourness" to coffee, such as citric acid, malic acid, acetic acid, phosphoric acid (phosphoric acid is an inorganic acid), tartaric acid, lactic acid, etc.

These acids are affected by heat during the roasting process, and most will gradually decompose. As roasting time extends, the content of organic acids that provide sourness will decrease.

Therefore, the more deeply roasted the coffee beans, the lower the acidity, and conversely, the higher the acidity.

Sour or Bitter: Which is Better?

I think no one can answer this question. A thousand people have a thousand favorite tastes.

Some prefer the gentle acidity reminiscent of fruit aromas, fresh and charming, while others are devoted to the mellow and rich bitterness.

A delicious coffee will be fragrant and rich in the mouth, with a mellow sweet aftertaste, without uncomfortable bitterness or acidity—only the surprise of various aromas releasing sequentially in the mouth. And in terms of feeling, a good coffee can bring physical and mental pleasure.

The experience of taste can bring people endless imagination, which is exactly what makes coffee interesting.

Can Coffee Acidity Be Removed?

If you can't accept acidity, I suggest adjusting from the coffee bean selection stage.

Coffee beans from some regions will have more acidic flavors, such as those from Costa Rica and Ethiopian growing regions. For those who prefer sweetness, try Indonesian coffee beans and Brazilian coffee beans, which will be more fragrant and mellow.

Actually, our coffee cherries are very similar to cherries. Coffee beans are the seeds inside coffee cherries.

Remove the outer shell, and we can see the coffee beans inside. The coffee we drink must be roasted, and roasting has different degrees of maturity. You can think of it like cooking steak.

Coffee with different roasting degrees will have different flavor characteristics.

Generally, medium to light-roasted coffee will retain more of the original fruity character of coffee and have higher acidity. Properly roasted coffee will also have good acidity—it's not just sour, it also has sweetness. The more deeply roasted the beans, the heavier the bitterness will be.

Translation: Coffee can have acidity, but it will gradually lose its acidity as the roasting degree increases.