What Makes Coffee Taste Bitter? Extracting the Truth

We’ve all been there. You take that first sip of coffee expecting a jolt of energy and smooth, rich flavor, but you get a mouthful of bitterness instead. Ugh. So, what gives? Why does coffee sometimes taste bitter?

I love to experiment with different coffee brewing methods. Unfortunately, that also meant I get it wrong and brew disastrous coffee more often than I’d like to admit.

After a lot of trial and error (and lots of bitter coffee), I discovered the leading causes of what makes coffee taste bitter. Check them out below, along with some tips on how to avoid bitterness.

What Makes Coffee Taste Bitter

How to know you are tasting bitter coffee

Your tongue is amazing! It can detect five different types of tastes:

  • Sweet
  • Salty
  • Sour
  • Umami (savory)
  • Bitter.

When you take a sip of coffee, your brain is actually getting information from two places: your taste buds and your olfactory sense (your nose).

Combining these tastes and smells gives you the complete flavor experience. When you taste something bitter, it is because your brain is receiving information from both your taste buds and your olfactory sense that the coffee is bitter.

Bitterness is detected on the back and sides of your tongue and is often described as sharp, astringent, or dry. So if you get a hit of bitterness in those areas, that’s a good indicator that the coffee is indeed bitter.

What Makes Coffee Taste Bitter

Bitterness isn’t all bad

While it’s certainly not the most pleasant taste, bitterness does have its purpose. In small doses, bitterness can add depth and dimension to your coffee. It’s only when bitterness becomes overwhelming that it becomes a problem.

So, if you’re aiming for a well-rounded cup of coffee with complex flavor, a little bit of bitterness is a good thing. Proper extraction will also pull out your beans’ sweet and fruity flavors and their natural oils, which will add body and mouthfeel.

The key is to find the perfect balance of all these flavors so that none of them overpowers the others. When done right, the result is a cup of coffee that is truly greater than the sum of its parts.

So, what causes bitterness in coffee? Well, let’s jump right in.

Your coffee is steeping too long and over extracted

Over-extracted coffee is by far the most common reason for bitter coffee. This happens when you extract too much of the coffee oils from the beans during brewing. The more you extract, the more bitter taste the coffee will have. There are a few different ways to prevent over-extraction, but the most important thing to remember is that time is of the essence.

Brewing coffee is a bit like cooking. You need to extract the flavors from the beans, but if you cook them too long, they’ll become overcooked and bitter. The same is true for coffee brewing. The sweet spot for most brewing methods is somewhere around 4-5 minutes. After that, the coffee will start to become bitter.

For example, if you’re using a French press, make sure to press down on the plunger as soon as your timer goes off. If you’re brewing with a pour over cone, remove the cone from the cup as soon as the brewing is finished. And if you’re using an automatic drip coffee maker, make sure to remove the coffee grounds from the filter as soon as the brewing cycle is complete.

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The grind is too fine

Another common cause of bitterness is using a grind that’s too fine. If the coffee grinds are too small, they’ll extract more quickly and lead to over-extraction (and, you guessed it, bitterness).

The easiest way to avoid this is to use a coarser grind. If you’re using a pour over cone, for example, try using a grind that’s on the coarse side. You may need to experiment a bit to find the perfect grind size for your brewing method, but starting with a coarser grind is an excellent place to start.

If your brew starts tasting sour, you’ve gone too coarse and are now under extracting. In that case, you’ll want to use a finer grind next time.

You’re using too much coffee

Another common mistake is using too much coffee. This might seem counterintuitive – more coffee should mean more flavor, right? Well, not necessarily.

If you use too much coffee, the water will have difficulty extracting all of the flavors from the beans. This can lead to an uneven extraction, with some of the coffee oils being extracted and others not. The result is often a bitter, astringent cup of coffee.

To avoid this, make sure to use the correct amount of coffee for your brewing method. A good rule of thumb is to start with two tablespoons of coffee per 6 ounces of water. From there, you can adjust the ratio up or down depending on your preferences.

You’re using old coffee beans

Coffee beans go stale quickly after they’re roasted. After about two weeks, they’ll start to lose their flavor and become more bitter. So, if you’re using coffee that’s more than a couple of weeks old, it’s likely that the bitterness is coming from the beans themselves.

To avoid this, make sure to buy fresh coffee beans and use them within a few weeks of purchase. Alternatively, you can store your beans in an airtight container to help them stay fresh for longer.

Why Does My Coffee Taste Like Water

Your water is too hot

Time and temperature are two important factors when it comes to brewing coffee. If your water is too hot, it will extract more of the coffee oils, leading to a bitter cup of coffee.

The ideal brewing temperature for most methods is between 195 and 205 degrees Fahrenheit. If your water is boiling (212 degrees Fahrenheit), let it sit for a minute or two to cool down before using it.

Boiling hot water can scorch the coffee beans and make the coffee taste burnt. If your coffee tastes burnt, it’s likely the water was too hot.

If you don’t have a variable temp gooseneck kettle, you can also use a thermometer to ensure your water is at the correct temperature.

You’re not pre-rinsing your coffee filter

If you’re using a paper coffee filter, rinse it with hot water before brewing. This will help remove any residue from the manufacturing process and prevent it from ending up in your cup.

Not rinsing your filter can lead to more than just bitter flavors. The paper fibers can also end up in your coffee, giving it a papery taste.

What Percentage of Coffee is Water?

You’re not using freshly filtered water

Another common cause of bitterness is using water that’s not fresh. If your water tastes bad, it’s likely that your coffee will as well.

To avoid this, use filtered or spring water for brewing. This will help remove any chance of impurities that could cause bitterness.

Your brewing equipment is dirty 

If you don’t clean your coffee maker on a regular basis, oils and residue from previous brews can build up and make your coffee taste bitter. To clean your coffee maker, simply run a cycle with vinegar and water (equal parts) instead of just water.

Don’t forget to rinse afterward with just water to remove any residual vinegar taste!

You should also be sure to clean or replace your permanent filters regularly as well—old or clogged filters can also contribute to bitter-tasting coffee. 

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You’re using the wrong type of coffee beans

Finally, it’s worth noting that different types of coffee beans can taste more or less bitter. For example, Arabica beans are more mellow and balanced, while Robusta beans are often described as more aggressive and bold.

So, if you’re finding that your coffee is always bitter, it might be worth trying a different type of coffee bean. You may also want to experiment with other brewing methods to see if that makes a difference.

Light roast specialty coffee can be harder to brew and lead to more bitterness if you’re not careful. If you’re new to brewing coffee, it might be worth sticking to a medium or dark roast. These coffees are typically more forgiving and easier to brew.

Final thoughts on why coffee tastes bitter

There you have it! There are a number of different factors that can contribute to bitterness in coffee. By troubleshooting each of these potential problems, you should be able to pinpoint the issue and fix it.

In general, the best way to avoid bitter flavor is to start with fresh beans and use filtered water. From there, be sure to clean your brewing equipment regularly and experiment with different brewing methods to find the perfect cup of coffee for you. Happy Caffeinating!

About the Author Kris Silvey

About the Author Kris Silvey

As a semi-professional at-home barista and full-time software engineer, my love for coffee borders on obsession. By combining my passion for coffee with an engineering mindset, I strive to perfect my brewing process and share that knowledge with each of you.

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