Why Your Coffee Tastes Bitter (and How to Fix It)

We've all brewed a cup of coffee that makes us grimace. A harsh, dry, astringent bitterness that coats the back of your throat.

While some bitterness is natural (it balances the sweetness and acidity), excessive bitterness is a brewing flaw known as over-extraction. It means you have pulled too many soluble compounds out of the coffee grounds.

Here is how to fix it.

1. Grind Coarser

This is the most common culprit. When you grind coffee very fine, you expose a massive amount of surface area to the water. The water extracts flavors much faster.

If your coffee is bitter, your grind is likely too fine. Solution: Adjust your grinder to a coarser setting. This reduces the surface area and slows down the extraction process.

2. Decrease Water Temperature

Coffee extracts faster in hotter water. If you are using water straight off a rolling boil (100°C), you are likely scorching the coffee and rapidly over-extracting the bitter compounds.

Solution: Let your kettle sit for 30-60 seconds after boiling, aiming for a temperature between 90°C and 96°C. Darker roasts extract very easily, so use cooler water (around 90°C) for them.

3. Shorten the Brew Time

The longer water sits in contact with coffee grounds, the more it extracts. If your French Press steeps for 10 minutes, or your espresso shot takes 50 seconds, it will be bitter.

Solution:

• Immersion (French Press/Aeropress): Plunge and pour earlier.
• Percolation (Pour-over/Espresso): This is tied to grind size. Grinding coarser will allow the water to flow through faster, naturally shortening your brew time.

4. Increase Your Dose (Use More Coffee)

This sounds counterintuitive, but if you use too little coffee for a given amount of water, that large volume of water will over-work the small amount of coffee, stripping out every last bitter compound.

Solution: Check your ratio. If you are using a 1:18 ratio (1 gram of coffee for every 18 grams of water) and it tastes bitter, try a 1:15 ratio.

Remember, always change one variable at a time so you know what fixed the problem!