What makes coffee bitter

Here’s What Makes Coffee Bitter [Top Reasons + Fixes]

Coffee features a certain level of bitterness by default, but sometimes, it can simply be excessively bitter. And a harsh dose of bitterness can only ruin your mornings. Yet, what is it that violates your taste buds that much? What makes coffee bitter?

Here are some of the most common factors that can make your coffee bitter:

  • Using old or stale beans
  • Dirty brewing equipment
  • Going to extremes with the coffee-to-water ratio
  • Applying wrong brewing methods
  • Over-steeping 

But what if you try your best to make a burst of awesome flavor but end up frowning?

Then check out the top 8 reasons that can mess up your coffee routine, as well as 8 easy-to-apply fixes!

Top 8 Reasons Your Coffee Taste Bitter & 8 Easy Ways to Fix it!

Keep in mind that each of these factors can affect how bitter your java is, so make sure to try our 8 neat fixes to improve your cups and make your bitter coffee… less bitter!

1. Over-Steeping

The longer your coffee steeps in hot water, the more bitter it’s going to be.

This is especially common if you have one of the “press” coffee makers – the AeroPress or the French Press.

Basically, if you push the plunger down and leave the coffee in the press, this will inevitably result in over-extraction.

Also, coffee residue can make your next cups even bitterer.

It is a bit of a challenge to get the extraction just right so that you manage to retain the oils and original flavors in your cups, while not going overboard.

The biggest catch with the “press” coffee is that you can end up with either harsh or sour cups.

Over-steep your coffee and your cups will taste burnt, period.

Yet, if you don’t extract it enough, it will taste weak and almost watery.

However, over-steeping is practically impossible with drip coffee makers or automatic espresso machines so keep that in mind.

The Fix

If you are brewing coffee with a French press, reduce the steeping time for 1 to 2 minutes, or set a timer.

Additionally, you can transfer the content to a glass or thermal carafe once you’re done brewing.

What makes coffee bitter, wrong brewing temeprature

2. Wrong Brewing Temperature

Over-boiling water (to temperatures of 212 F degrees and higher) will bring out the bitter compounds in your coffee.

And this is typically a problem of drip coffee makers since most don’t have temperature control settings.

While with the French press and pour-over coffee makers, you can control the temperature of the water more easily.

What makes coffee bitter, thumbs up

The Fix

Don’t boil the water at temperatures higher than 205 F degrees and this obviously applies to brew methods such as pour-over.

Once the water reaches the rolling boil stage, just take it off the heat source to prevent your coffee from getting burnt.

Let the water simmer down for 30 to 45 seconds before pouring it over the grounds.

However, be careful not to leave the water stay in contact with the coffee grounds for longer than 1 minute.

Otherwise, your cup of Joe will be too bland.

What makes coffee bitter, over-steeping

3. Wrong Brewing Method

Applying wrong brewing methods can affect how the flavor compounds in your cups dissolve.

This in return can make your coffee bitter or sour.

For instance, under-extraction will make a coarse grind flat.

While over-extracting finely ground coffee will make your cups more bitter.

What makes coffee bitter, thumbs up

The Fix

Different grind sizes require different brewing methods.

Here’s which method works best with the various grind sizes.

  • Medium grind – Regular coffee maker and flat filters
  • Coarse grind – French press or a percolator
  • Fine grind – Coffee maker with a cone-shaped filter
  • Extra-fine grind – Steam espresso machine

And if you have a burr grinder, you can experiment with grind sizes until you discover the right one.

So if your cups are overly bitter, then go for a little coarser grind.

What makes coffee bitter, old coffee residue

4. Old Coffee Residue

If you are not cleaning your brewing equipment regularly, then coffee residue will slowly build up.

And this can definitely make your cups bitter and unappetizing.

As a general rule of thumb, the more old coffee residue found in your brewer, the bitter and staler your java will be.

What makes coffee bitter, thumbs up

The Fix

Rinse your gear after each use (if possible, while the filter cone and carafe are still hot) to neutralize any acidity.

Use a long-handled brush and baking soda to scrub any leftovers in the filter.

Even better, you can apply this method to various brewers including drip coffee makers, French press and pour-over makers.

And if you have an automatic drip coffee maker, just run fresh water through it as that should suffice.

What makes coffee bitter, stale beans

5. Stale Beans

There’s no doubt that stale beans can add up to the bitterness of your cups.

If you are a coffee enthusiast, you will notice an odd smell even before brewing.

Roasted beans will typically “go bad” after 5 to 6 months, even if you store them in a cool and dry place.

But this doesn’t apply to green beans since they can stay good for a few days max.

And coffee beans start losing their peak flavor in just a couple of hours after your roast them.

What makes coffee bitter, thumbs up

The Fix

Buy only as many coffee beans you can use within a week.

Grind the approximate amount of coffee you need per day or per portion.

And you should store your beans in a container to keep them fresher for longer.

What makes coffee bitter, dark roasts

6. Dark Roasts

It’s not only about which grind size you go for, but also what roast type you are using.

Darker roasts such as French, Italian, Continental, Viennese, or Espresso varieties are stronger and bitterer than medium-dark or light roasts.

If your cups taste like charcoal, then you most likely went for the wrong roasting profile.

What makes coffee bitter, thumbs up

The Fix

Try a couple of the light roasts such as Half City or Cinnamon to eliminate the dreaded bitterness.

Or if you’re after more defined roasts you can also try Breakfast or American roasts.

Most roasters print indicators on each bag related to how light/dark their coffee is, which can help you find that sweet spot easier.

What makes coffee bitter, Robusta coffee beans

7. Robusta Coffee Beans

Using Robusta beans will translate in coffee that’s quite bitter, especially when compared to Arabica.

The specific Robusta coffee plants produce beans that are way bitter than their Arabica counterparts.

However, Robusta features higher levels of caffeine and it is also more affordable, which is why it is so popular.

Arabica beans, on the other side, require more care and cost more but they boast a better flavor profile as well.

What makes coffee bitter, thumbs up

The Fix

Instead of using Robusta, try looking for more balanced coffee beans such as Arabica.

Especially Costa Rican or Brazilian beans as they are known for their balanced flavor profiles and lack of profound bitterness.

What makes coffee bitter, water-to-coffee ratio

8. Water-to-Coffee Ratio

If you add too much coffee and not enough water, you will end up with a cup of bitterness.

That’s why utilizing the correct and adequate water-to-coffee ratio is essential if you want great tasting coffee that’s not as bitter.

But don’t assume that just adding lots of water will suffice as that will only make your java taste bland and watered down.

You need to measure things precisely for the best results.

What makes coffee bitter, thumbs up

The Fix

Add 1 gram of coffee per 18 grams of water if you are sensitive to bitterness.

But if this seems too bland, go for 16:1 water-to-coffee ratio for a stronger drink.

Alternatively, you can also opt for 19:1 ratio if you can still feel the bitterness – feel free to play around with different ratios.


So, what makes coffee bitter?

Here are some of the main factors to consider:

  • Dark roast profiles
  • Over-steeping
  • Stale beans
  • Leftovers
  • The amount of coffee you add per cup

Anyway, you’re now familiar with the top 8 reasons for bitter java and more especially, you now know how to make coffee less bitter.

Now – do you mind unbalanced, overly bitter types of coffee?

And how do you get rid of the bitter taste in your mouth?

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