If you’ve ever sipped your espresso and thought, “Why does this taste weird?” — you’re not alone. Sour, bitter, thin, or overly strong coffee is almost always a brewing issue, not a bean issue.
And more often than not, it comes down to one thing: extraction.
In this article, we’ll walk through what extraction is, how to tell the difference between under-extracted and over-extracted coffee, and how to fix both with simple adjustments.
What is Coffee Extraction?
Extraction is the process of using hot water to pull flavours, oils, acids, and solubles out of ground coffee. Ideally, you want to extract the right amount — not too little, not too much.
When you hit that sweet spot, you get a smooth, balanced cup with great body and clarity.
But when extraction is off? The flavours fall apart.
What is Under-Extraction?
Under-extraction happens when you don’t pull enough out of the coffee grounds. The water either moves too quickly through the puck or doesn’t spend enough time extracting key compounds.
How to Identify It:
- Tastes sour, acidic, or sharp
- Feels thin or watery
- Sometimes has a salty or metallic edge
- Sourness hits the sides of your tongue
Common Causes:
- Grind size is too coarse
- Shot time is too short
- Dose is too low or not properly distributed
- Water flows through too quickly
How to Fix It:
- Grind finer to slow the flow
- Increase brew time slightly
- Check that your puck is evenly distributed and tamped
What is Over-Extraction?
Over-extraction is the opposite — you’ve taken too much from the coffee, including the compounds that taste dry, bitter, or unpleasant.
How to Identify It:
- Tastes bitter, harsh, or burnt
- Feels chalky, drying, or overly strong
- Bitterness lingers on the back of your tongue
Common Causes:
- Grind is too fine
- Shot runs too long
- Dose is too high or puck is over-compressed
- Water sits too long with the grounds
How to Fix It:
- Grind coarser to speed up flow
- Reduce your brew time
- Keep your dose within your portafilter’s limits
The Goal: Balanced Extraction
Dialing in isn’t about chasing perfection — it’s about achieving balance.
A properly extracted espresso:
- Has clarity and sweetness
- Feels smooth and full-bodied
- Leaves a clean finish
- Doesn’t lean too bitter or too sour
If you can consistently hit that zone, your espresso will taste noticeably better — no matter what gear you’re using.
Not Sure Which Way You're Off?
Here’s a quick cheat sheet:
| Symptom | Likely Cause | Adjustment |
|---|---|---|
| Sour & sharp | Under-extracted | Grind finer, slow shot |
| Bitter & dry | Over-extracted | Grind coarser, speed up shot |
Tip: What you taste matters more than what the timer says. Trust your tongue.
Want to Go Deeper?
We cover extraction fundamentals — including practical guides, visual cues, and ratio recipes — in our free Sub Club extraction eBook.
Sub Club members also get:
- Free express shipping
- Priority handling
- Bonus resources like this one
Still not sure if your shot is sour, bitter, or beautifully balanced? Shoot us a message — we’re always happy to help.