Recognizing Bitterness
Not all bitterness is bad. Dark chocolate, roasted nuts, and caramel all contribute pleasant bitterness. The problem is harsh bitterness that dominates the cup and dries out your mouth.
Pleasant Bitterness
- • Smooth, rounded
- • Chocolate or nutty quality
- • Balanced with sweetness
- • Clean aftertaste
Harsh Bitterness
- • Sharp, metallic edge
- • Dries out your mouth
- • Tastes burnt or ashy
- • Lingers unpleasantly
Test: If the bitterness gets worse as the coffee cools, it is over-extraction. Pleasant bitterness stays balanced at all temperatures.
What Causes Bitterness
Bitterness is almost always caused by over-extraction. You have dissolved too much material from the coffee, including undesirable bitter compounds that extract last.
1. Grind Too Fine
High surface area combined with long contact time extracts everything from the coffee, including harsh tannins and bitter chlorogenic acids.
2. Water Too Hot
Excessively high temperatures (above 96°C) increase extraction efficiency and dissolve compounds you do not want. Especially problematic with darker roasts.
3. Contact Time Too Long
If your brew takes 4+ minutes for pour-over or you steep immersion too long, you extract past the sweet spot into harsh territory.
4. Hard Water / High Mineral Content
Water with high calcium and magnesium content increases extraction efficiency. Good for under-extracted coffee, bad if you are already extracting too much.
Important Note
Very dark roasts (French, Italian) will always taste somewhat bitter due to roast development. If your light or medium roast tastes bitter, it is an extraction issue.
How to Fix Bitter Coffee
Follow these steps in order. Make one adjustment at a time and taste before continuing.
Step 1: Grind Coarser
This is the most effective fix. Reduce surface area so less material extracts in the same time.
Try this: Go 2-3 clicks coarser. If you are on a Comandante at 15, go to 18. On a Baratza at 12, go to 15.
Step 2: Lower Water Temperature
If grinding coarser helps but does not eliminate bitterness, reduce temperature.
Try this: If brewing at 95°C, drop to 90-92°C. For dark roasts, you can go as low as 85-88°C.
Step 3: Shorten Contact Time
If your brew takes longer than 3:30 for pour-over, speed it up.
Try this: Pour faster and more aggressively. For immersion, draw down or plunge sooner (try 2:30 instead of 4:00).
Step 4: Check Your Water
If bitterness persists across all adjustments, your water might be too hard.
Try this: Brew with bottled water (like Crystal Geyser or reverse osmosis water) to see if bitterness improves.
Warning
If you grind coarser and coffee becomes sour, you had uneven extraction (some under, some over). Fix channeling with better distribution or agitation instead.
When It Is Not Over-Extraction
Occasionally bitterness comes from sources other than brewing. Here are edge cases to consider:
Stale or Defective Coffee
Old coffee (6+ months past roast) develops stale, cardboard-like bitterness. Defective beans (quakers, mold) also contribute harsh bitterness.
Dirty Equipment
Coffee oils build up in grinders and brewers, then go rancid. Clean your equipment regularly. Bitterness from rancid oils tastes stale and greasy.
Uneven Roast Development
Some roasters over-develop the surface of the bean while leaving the interior under-roasted. This creates simultaneous bitterness and sourness. No brew adjustment will fix this.