Guide · As of October 2026
Bitter espresso has two common causes. Either it is over‑extracted because the grind is too fine, it was brewed too hot, or the shot was pulled for too long. Or the machine is dirty and old coffee oils give a rancid‑bitter taste. The second cause is most often overlooked.
A little bitterness belongs to espresso, especially with dark roasts. It becomes a fault when it covers everything else, dries out the mouth and lingers for a long time.
Step 1: Clean machine and grinder
Coffee contains oils. They deposit in the group head, in the portafilter and in the grinder and become rancid over time. Every fresh shot then runs through old residues.
- Backflush the group head. With a blind basket and a coffee‑fat cleaner like Puly Caff. With clear water at the end of each day, with cleaner in household use about every one to two weeks. This applies to machines with a solenoid valve. Check the manual to see if your machine may be backflushed.
- Soak baskets and portafilter. In hot water with cleaner, then rinse thoroughly.
- Brush the shower screen. With a group brush, for example the group head cleaner from Pallo.
- Clean the grinder. Old fines and oil in the burrs also taste bitter. There are grinder cleaners for that.
If the espresso tastes noticeably better after cleaning, that was the cause.
Step 2: Measure the shot
Weigh what goes into the basket and what comes out, and time the shot. Target values for our beans in a double basket:
| Bean | In | Out | Time | Temperature |
|---|---|---|---|---|
| Ätna, Vesuv | 17 to 18 g | 34 to 38 g | 25 to 28 s | 91 to 92 °C |
| Hausblend N°1, Bergkraft | 17 to 18 g | 36 to 40 g | 28 to 32 s | 93 to 94 °C |
If your shot lasts significantly longer, it is over‑extracted.
Step 3: Grind coarser
Too fine a grind slows the water. It stays in contact with the coffee too long and extracts the bitter compounds that come late. Set the grinder coarser in small steps until the time is right.
Step 4: Brew cooler
Dark roasts tolerate less heat. We brew Ätna and Vesuv at 91 to 92 °C, two degrees cooler than our medium roasts. For both: brew cooler and shorter, otherwise the espresso becomes bitter.
On machines without temperature control, a short blank shot before the espresso helps. It flushes overheated water from the brew group.
Step 5: Shorten the shot
The last grams of a shot mainly bring bitterness. Stop earlier: instead of 40 g only 34 to 36 g. With very dark beans a ristretto can also be the better choice. More on this: Ristretto, Espresso, Lungo.
Step 6: Bean and water
- Old beans. Coffee that has stood open for months tastes flat and bitter. How to store correctly: How to store organic coffee beans properly.
- Too dark for your taste. Very dark roasts are naturally more astringent.
- Limescale. Machines with limescale heat unevenly. Descale regularly, for example with Decal40, and follow the manufacturer's instructions. A water filter in the tank delays limescale buildup.
Which bean if you want low bitterness?
Hausblend N°1: dark chocolate, nougat, a hint of citrus. Medium roasted, more forgiving than a dark roast.
Hochlandblüte: washed Ethiopian, floral, red berries, clear and sweet. Hardly any roast bitterness, more acidity instead.
Nachtgold Decaf: forest honey, fig, milk chocolate. Round and sweet, without caffeine.
Those who love dark roasts and still want no bitterness should stick to Ätna and keep to 91 to 92 °C and at most 28 seconds.
Frequently asked questions
Why does my espresso taste bitter?
Most often it is over‑extracted, i.e. too finely ground, brewed too hot or pulled too long. Equally common are old coffee oils in the group head, portafilter or grinder.
What helps fastest against bitter espresso?
Clean the machine and backflush. Then grind coarser until the extraction time is 25 to 32 seconds.
What temperature to avoid bitter espresso?
Lower. Dark roasts at 91 to 92 °C, medium roasts at 93 to 94 °C.
How often do I have to clean the portafilter machine?
With clear water after each day, with coffee‑fat cleaner in household use about every one to two weeks. More often with several shots per day.
Are dark beans always bitter?
They are more astringent, but not necessarily unpleasantly bitter. Brewed cooler and shorter they taste chocolaty.
Bitter or sour, how do I tell the difference?
Bitterness sits at the back of the tongue and lingers. Sour pulls at the front and sides and disappears quickly. What helps with sour espresso: Espresso too sour.
Read more: Espresso too sour · Espresso runs too fast or has no crema · Do I need a water softening system?
