Why does a coffee taste burnt?

Last Updated on October 24, 2023 by Pablo Barrantes

It must have happened to you as it did to me that sometimes in coffee shops and supermarkets, I find coffees that have an unpleasantly strong, burnt, and bitter taste. On the other hand, sometimes, the coffee tastes watery and flat in flavor.

This article will explore the possible causes behind these errors and how they can be avoided. On many occasions, if the coffee beans are of very poor quality, there is little that can be done, but on others, we can improve the taste significantly.

What causes the strong burnt (bitter) taste of coffee?

Although it is common to think that coffee is naturally bitter, this is not entirely true. The bitterness of coffee is mainly due to the roasting process and caffeine. Caffeine is a bitter substance that can be even more pronounced in Robusta coffees, which contain twice as much caffeine as Arabica coffees.

However, quality coffee should not be excessively bitter. Still, it should allow the fresh and acidic notes of citrus or red fruits to be appreciated, as well as the sweet touches of chocolate and ripe fruit.

➡️ So why are many commercial coffees so bitter? The main reason lies in the roasting process: many roasters darken the beans excessively until they turn black and burn, resulting in unpleasant coffee in the cup.

Other reasons why coffee tastes burned and bitter

Excessive roasting of the coffee bean is the most obvious and common reason why coffee tastes excessively bitter or burnt. However, other causes are worth mentioning:

  • In the first place, if the water temperature is too high, the ground coffee can burn, which will contribute to the beverage’s bitter taste.
  • Secondly, a dirty coffee pot can result in a musty, tarry, ashy, or rancid odor in the beverage. Used coffee residues, rich in oils and fats, can oxidize and contribute to this unpleasant taste.
  • Thirdly, the chlorine in the water can affect the taste of coffee. It is recommended to use filtered or bottled water to avoid this problem.
  • In addition, the coffee maker used to extract coffee can also affect its taste. For example, coffee prepared in a Moka pot can be more bitter than a paper filter, although the latter can have a less intense flavor.
  • Finally, an over-extracted coffee beverage can be more bitter. The hot water extracts more substances from the ground coffee and can result in a burnt and bitter taste.

It should be added that the proper grind size is fundamental for the quality of the coffee, even if a high-quality raw material is used. If adjusted correctly, a delicious cup of coffee will be obtained.

When is coffee considered to be watery?

Unlike the aforementioned, coffee can be flat, tasteless, sour, and astringent, commonly known as “dirty water”. This type of coffee produces an astringent sensation similar to that felt when eating an unripe banana, which leaves dryness on the palate and an unpleasant gritty sensation in the mouth.

What factors influence the lack of intensity of coffee?

The lack of intensity of coffee can depend on several factors:

  • Incorrect roasting, which occurs when roasting lasts too long and at low temperatures, can cause a defect called Baking, which causes the coffee to become flat, without aroma, and with an unpleasant taste.
  • Under extraction of the beverage can also be an important factor, that is, when less is extracted than should be extracted. If the ground coffee is too large, the water is drained without having time to infuse it with the ground coffee and contribute oils, lipids, and aromatic notes to the cup.

Therefore, an incorrect roasting and an extraction that is too fast can cause the coffee we drink to have neither body nor intensity, resembling rather “dirty water”.

Is filtered coffee considered a watery coffee?

It is important to clarify that filtered coffee should not be considered watery coffee.

Frequently, we think of filter coffee instead of a badly prepared beverage when we speak of watery coffee, but this is incorrect.

Filter coffee, which should not be confused with Americano (espresso diluted with hot water), is prepared using a paper or metal filter (Italian coffee maker). The filter houses a determined amount of ground coffee, through which hot water is filtered until the final beverage is obtained.

➡️ The result is a less concentrated and creamy coffee than an espresso, but it is not bitter, being a very aromatic, sweet, acidic, and tasty beverage. And although the cream is not visible in the cup, an explosion of aromas can be felt on the palate.

Therefore, filter coffee should not be considered watered down; it is a different method of preparing the beverage than espresso.

Related: Differences between cappuccino, latte and latte macchiato.

Written by Pablo Barrantes
I'm Pablo Barrantes, an industrial engineer, and a proud dad to an 8-year-old princess. I'm also a coffee enthusiast who's truly passionate about all things coffee and coffee makers. My enthusiasm has driven me to uncover the hidden secrets of the coffee world, and I'm committed to sharing this knowledge with everyone through my educational blog. In this blog, you'll find valuable and practical information to enhance your coffee experience. What brings me the most joy is knowing that the tips and solutions you discover here will make your coffee moments even more delightful. When I can help you troubleshoot coffee machine issues, and you can savor your coffee without a hitch, it brings a smile to my face.

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