Unmasking the Culprit: What Causes Bitter Coffee?

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Ever had a sip of your morning coffee and cringed at an unexpected bitterness? You’re not alone. Many coffee lovers wonder, “What causes bitter coffee?” Understanding the dynamics behind coffee’s flavor profile can help you achieve that golden cup that strikes the right balance of flavors. From coffee grounds to brewing methods, let’s journey together into the aromatic world of coffee and debunk the bitter myth.

What Causes Bitter Coffee?

When it comes to coffee, bitterness often derives from a complex interplay of factors, including water temperature, the quality and roast profile of the coffee beans, the brewing method, and more. Over-extracted coffee, stale beans, or even wrong grind sizes can turn your beloved morning potion against your taste buds.

What Causes Burnt Coffee

Here are the main culprits behind bitter coffee.

1. Coffee Compounds

Coffee contains numerous volatile organic compounds; among them, chlorogenic acids and chlorogenic acid lactones, both of which play a significant role in creating a bitter taste in your cup4. When green coffee beans are roasted, they undergo chemical reactions that break down chlorogenic acids, forming bitter-tasting lactones5. As a general rule, the more the coffee beans are roasted, the higher the concentration of lactones, leading to a more pronounced bitterness in the coffee6.

What Causes Bitter Coffee? Table
Note: The specific percentages used here are arbitrary and are meant for illustrative purposes only.

2. Water Temperature

According to the Specialty Coffee Association of America, when brewing coffee, keep the water temperature between 195-205°F. Too hot, and the water over-extracts the coffee, pulling out undesirable bitter compounds. On the flip side, cooler water can lead to under-extracted coffee, introducing an unpalatable sourness.

3. Grind Size

The taste of your coffee is greatly influenced by your coffee grinder, whether it’s a blade grinder or a burr grinder. The surface area of the coffee grounds plays a crucial role in the extraction process. Finer grinds increase the surface area that comes in contact with hot water, causing faster extraction, while coarser grinds slow it down.

Artboard 6@3X 100 1
Coffee grind guide

Grinding your beans excessively can produce an over-extracted, bitter coffee, while a too-coarse grind can lead to a flat and underwhelming flavor.

4. Time Spent on Burner

If you use a drip coffee maker with a burner/hot plate, you may have experienced the bitter taste of overcooked coffee. The longer your brewed coffee sits on the warmer, the more it becomes bitter.

This happens because two things occur: the water slowly evaporates, making the coffee taste stronger, and the coffee keeps getting heated, similar to cooking. As a result, the natural sugars in the coffee start to burn, giving it a burnt flavor.

Coffee Maker With Thermal Carafe
The Capresso CoffeeTEAM PRO Plus has a thermal carafe and a built-in, self-cleaning conical burr grinder.

If this happens to you often, you might want to consider investing in a coffee maker equipped with a thermal carafe. These carafes can help keep your coffee hot for up to 4-6 hours without using a hot plate, which can prevent the coffee from becoming bitter.

Three Key Ingredients for Brewing the Perfect Coffee

1. Brew-Time

In brewing coffee, getting the timing right is key. Brew it for too long, and you’re left with a bitter, not-so-great taste. The National Coffee Association recommends going for a 4-minute brew if you’re using a French press and keeping it to around 20-30 seconds for espresso.

The good news is, if you’re using a regular coffee machine, it’s got your back. These machines are typically built to brew coffee for just the right amount of time, so you can rely on them to deliver a good cup.

2. Brewing Method

The coffee maker you use and the time you let it brew really affect the taste. It can make your coffee bitter or just right. So, picking the right coffee maker and brew time is key to a great cup of coffee.

There are loads of coffee makers out there, and they’re all different. From the classic stovetop espresso maker (sometimes called a moka pot) to the regular drip coffee maker, and even the cool cold brew maker. Each one has a unique way of getting the tasty flavors from the coffee beans.

Pouring Coffee Into A Mug From A Moka Pot
A moka pot makes rich, espresso-like coffee

3. Water Quality

The water you use for making coffee matters a lot. Tap water can make your coffee taste bitter, while pure water can make it dull. The best choice is spring water, which has just the right amount of minerals. If you’re making cold brew, using ice-cold spring water is even better for a tasty cup.

How to Get Rid of the Bitter Taste in Coffee

There are several ways to reduce the bitterness in coffee:

  • Adding a dash of salt to your coffee can help suppress the bitterness and enhance the flavor​7.
  • Adjusting the water temperature can also help. Ideally, the water should be between 195 and 205 degrees Fahrenheit. Any hotter, and you can over-extract the bitter flavors​​.
  • Be careful not to steep your coffee for too long, as this can lead to over-extraction and increase bitterness​.
  • Regularly cleaning your coffee maker can also help reduce bitterness​​.
  • Using fresher beans or trying a different grind size or brewing method can also help​​.

Beans Matter

Sourcing the Best Beans

Choosing your beans can be as significant as any brewing variable. Robusta beans, known for their higher caffeine content, also contain more bitter compounds8 than their Arabica counterparts. Additionally, poorly stored beans or past their peak can turn stale, contributing to a bitter cup.

Related: 10 Best Coffee Containers

Typically, I use Kirkland coffee beans from Costco for my daily brew. However, once a month, I indulge in a special treat by purchasing a bag of Spirit Animal Coffee. These premium beans, which cost between $20 to $40 per bag, originate from micro-lots in Honduras.

Spirit Animal Coffee

Getting the Flavor Right with Roasting

If you love coffee, you know that the roast matters! The way coffee beans are roasted changes how your coffee tastes. Imagine roasting as cooking the beans – the longer you cook, the stronger the taste.

Dark roasted coffee has a strong, bitter taste because it has more of certain bitter things in it (think of them as flavor agents). Light roasted coffee is…less roasted, so it keeps more of the natural coffee taste but can be a bit tangy.

You can find some amazing coffee online. Online coffee shops often roast the beans in small amounts and send them to you quickly. That means they’re fresher than the ones sitting on the store shelves for weeks.

Here are three awesome online coffee roasters that I really like. My personal favorite is Volcanica.


Why does my coffee taste bitter suddenly?

It could result from over-extraction due to too fine a grind, too long a brewing time, or too hot water. Additionally, your beans might be overly dark-roasted or stale.

How can I make my coffee less bitter?

Adjust your grind size, brew time, and water temperature, or even try a different brewing method. You can also experiment with different roast profiles or bean varieties.

Does cold brew coffee taste less bitter?

Yes, cold brew coffee tends to taste less bitter as it uses cold water, which extracts fewer bitter compounds than hot water.

Does more coffee make the coffee more bitter?

Yes, using too much coffee can over-extract the bitter compounds, leading to a bitter-tasting cup. Stick to the golden ratio of approximately 1 to 2 tablespoons of coffee per 6 ounces of water.

Why is my French Press coffee always bitter?

This might be because you’ve been brewing for too long. Try reducing the brew time. Also, ensure that your grind size is coarser to match the French Press brewing method.

How does water quality affect my coffee’s taste?

Water with high mineral content or impurities can make your coffee taste off. Using fresh, clean water, preferably spring water, can enhance the taste of your coffee.

Why is coffee bitter if it is acidic?

The bitterness in coffee comes from the roasting process. When coffee beans are roasted, the chlorogenic acids in the beans are converted into bitter-tasting lactones. This is a crucial chemical step that turns the acidic chlorogenic acids into bitter-tasting compounds​9.​

Can COVID-19 cause coffee to taste bitter?

Post-COVID conditions, such as parosmia and parageusia, can distort smells and tastes, potentially causing coffee to taste bitter. These conditions are thought to affect roughly 10% of people who recover from their acute infection​10.

Is there a specific name for bitter coffee?

Bitter coffee is sometimes referred to as ‘Cafe Select.’ This term encompasses coffee, including green beans, broken beans, and cafe grains​11.


Knowing what causes bitter coffee is your first step towards mastering the art of coffee brewing. The right balance between the beans, water, brewing method, and timing can transform your daily coffee ritual into an exquisite sensory experience. Remember, while a touch of bitterness can add a complex flavor to your brew, an overpowering bitterness can mar your coffee experience.


  1. https://yourwisdomtips.com/why-coffee-has-a-bitter-taste-although-it-has-a-ph-of-5/
  2. https://www.news24.com/life/wellness/body/condition-centres/infectious-diseases/coronavirus/living-with-long-covid-everything-tastes-bitter-and-smells-like-sweat-or-a-fart-20211102-2
  3. https://convergentcoffee.com/coffee/bitter-coffee/
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8705492/
  5. Adriana Farah, Tomas de Paulis, Luiz C. Trugo, and Peter R. Martin, Journal of Agricultural and Food Chemistry 2005 53 (5), https://pubs.acs.org/action/showCitFormats?doi=10.1021%2Fjf048701t&href=/doi/10.1021%2Fjf048701t
  6. Kraehenbuehl K, Page-Zoerkler N, Mauroux O, Gartenmann K, Blank I, Bel-Rhlid R. Selective enzymatic hydrolysis of chlorogenic acid lactones in a model system and in a coffee extract. Application to reduction of coffee bitterness. Food Chem. 2017 Mar 1;218:9-14. doi: 10.1016/j.foodchem.2016.09.055. Epub 2016 Sep 8. PMID: 27719962. https://pubmed.ncbi.nlm.nih.gov/27719962/
  7. https://www.wikihow.com/Reduce-Bitterness-in-Coffee
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7492344/
  9. https://yourwisdomtips.com/why-coffee-has-a-bitter-taste-although-it-has-a-ph-of-5/
  10. https://www.news24.com/life/wellness/body/condition-centres/infectious-diseases/coronavirus/living-with-long-covid-everything-tastes-bitter-and-smells-like-sweat-or-a-fart-20211102-2
  11. https://convergentcoffee.com/coffee/bitter-coffee/
Avatar Of Kelsey Todd
With over two decades in the coffee industry, Kelsey is a seasoned professional barista with roots in Seattle and Santa Barbara. Accredited by The Coffee Association of America and a member of The Baristas Guild, he combines practical expertise with a profound understanding of coffee's history and cultural significance. Kelsey tries his best to balance family time with blogging time and fails miserably.

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