Sour vs Bitter Espresso — How to Fix Your Shot

Sour espresso is caused by under-extraction — the water didn't dissolve enough of the good flavour compounds from the coffee. The acids are extracted first, so a fast, under-extracted shot tastes sharp, sour, and one-dimensional. Common causes: grind too coarse, dose too low, shot time too short, water temperature too low.

Bitter espresso is caused by over-extraction — the water pulled too many compounds from the coffee, including harsh, bitter ones that come out last. The shot tastes ashy, dry, and unpleasantly strong. Common causes: grind too fine, dose too high, shot time too long (over 35 seconds), water temperature too high, or stale/dark-roasted beans.

To fix sour, under-extracted espresso: 1. Grind finer — this is the most impactful change 2. Increase your yield (let more liquid through) — e.g. go from 30g to 36g out 3. Check your water temperature — it should be between 92-96°C 4. Make sure your machine is fully heated (15-20 min warmup) 5. Use fresh beans (7-21 days off roast)

To fix bitter, over-extracted espresso: 1. Grind coarser — one step at a time 2. Reduce your yield — stop the shot earlier (e.g. 34g instead of 40g) 3. Reduce dose slightly (e.g. 17g instead of 19g) 4. Check your beans — very dark roasts extract faster and bitter more easily 5. Clean your machine — old coffee oils cause rancid bitter flavours

The universal starting point for espresso is a 1:2 ratio: • 18g of ground coffee in → 36g of liquid espresso out • Target time: 25-30 seconds If it tastes sour, grind finer or increase yield. If it tastes bitter, grind coarser or decrease yield. Adjust one variable at a time.

Taste is subjective and every setup is different. If you're going in circles trying to balance your shot, our AI barista can guide you through the process in real time — or talk to our expert for hands-on advice.