Good espresso depends on precision. Small deviations in grind size, dose, brew ratio , espresso temperature , or tamping quickly add up – and suddenly the shot of espresso tastes too bitter or too sour . In this guide, you'll learn which espresso mistakes are most common, how they manifest in the taste, and which steps reliably help.
Classification: Why small deviations change the espresso
Espresso is an extraction process under pressure. Water successively extracts acids, sweetness, and bitterness from the coffee grounds. The order remains the same – but you control how much of each phase is extracted through grind size, dose, time, temperature, and pressure. Even a slightly too fine or too coarse grind, brewing at too high a temperature, or uneven tamping can throw off the balance.
The goal is consistency: By controlling variables, you can precisely taste the effects of a change. The reward is reproducible results instead of lucky guesses – and the assurance of quickly identifying errors.
The 5 most common mistakes – and how they affect the taste
1. Incorrect grind size: too fine/too coarse
The grind size is the most important factor for espresso . Too fine a grind leads to over-extraction: the shot flows slowly, is dark, dry, bitter, and astringent. Too coarse a grind means under-extraction: the shot flows too quickly, tastes thin, grassy, too acidic , or hollow.
- Too fine: Flow rate < 1 ml/s, extraction time > 35 s at the same ratio, taste bitter/dark.
- Too coarse: flow rate > 2 ml/s, extraction time < 20 s, taste sour/hollow, little body.
2. Inaccurate dosage and brew ratio
Without scales, there's no consistency: Even a dose of ±0.2 g changes the resistance. The brew ratio (e.g., 1:2) defines how much beverage you extract from the dose. Too high a ratio with the same grind size can emphasize watery, bitter notes; too low a ratio often results in a salty, unbalanced taste.
- Fluctuating dose = changing flow rate.
- Inappropriate ratio = incorrect balance of acidity, sweetness, and bitterness.
3. Uneven tamping and channeling
Uneven tamping, lumps in the portafilter, or coffee grounds on the edge of the portafilter create channeling espresso : water seeks the path of least resistance and extracts unevenly. The result: simultaneously under- and over-extracted areas, sputtering, tingling, and a disjointed taste.
- Symptoms: splashing discharge, blond stream, uneven flow.
- Causes: inadequate distribution, uneven pressure, screen edge not clean.
4. Incorrect brewing temperature and unstable pressure
The espresso temperature determines how quickly substances are extracted. Too high a temperature emphasizes bitterness, too low an acidity. Unstable pressure amplifies fluctuations. Espresso machines with PID (pulse-controlled temperature) maintain a more stable temperature; without PID, flushing routines and precise timing are necessary.
- Too hot: dark, burnt notes, dry finish.
- Too cold: sharp acidity, little sweetness, watery body.
5. Old or improperly stored beans
Coffee is a fresh product. Old or openly stored beans lose CO₂ and aromatic complexity, extract unevenly, and taste flat, woody, or bitter. Oily, very dark beans age even faster. For specialty coffee and espresso, what matters is: freshly roasted and stored correctly.
- Too fresh (under 5-7 days): strong crema, unstable flow, carbonated.
- Too old (open for over 8–10 weeks): flat, bitter-woody, little sweetness.
Step-by-step solutions: How to avoid these 5 mistakes
Finding the grind size (dial-in) using time and ratio
Start with a 1:2 ratio as a base (e.g., 18 g in, 36 g out in 25–30 s). Adjust the grind so that you achieve the target time in seconds with a constant ratio.
- Set a benchmark: Determine the dose and target beverage quantity.
- Stop the supply as soon as the target quantity is reached – not based on intuition.
- Sour? Grind finer. Bitter/dry? Grind a little coarser.
- Cost: discard at least 1-2 shots after each change; mills have a delayed response.
Precise dosing and constant reference quantity
Place scales under the grinder and under the cup. This eliminates fluctuations.
- Dosage: Weigh to the nearest 0.1 g (e.g. 18.0 g).
- Output: Stop at target grams using a timer/door scale (e.g., 36 g).
- Pay attention to the sieve size: An 18g sieve performs better with 18g than with 16 or 20g.
- Shot-by-shot protocol: Note dose, output, time, and taste.
Distribution, WDT and even tamp
Clean distribution prevents channeling. A short WDT (Weiss Distribution Technique) declumps and distributes the coffee grounds evenly.
- After grinding: Tap off the edge, loosen any lumps (WDT needle).
- Leveling: Make the surface flat with a distributor or gentle shake.
-
Espresso tamping : Vertical, centered pressure (approx. 10–15 kg). Consistency is key, not brute force.
- Clean the sieve rim: No flour between the seal and the portafilter.
Temperature and pressure control, flush, pre-infusion
Set your machine to a stable position and ensure reproducible starting conditions.
- Temperature: 92–96 °C at the brew group. Light roasts slightly higher, dark roasts lower.
- Use PID: Constant temperature; test small steps of 0.5–1.0 °C.
- Flush: For heat exchangers, perform a short cooling flush before use until the hissing stops.
- Pre-infusion: Wet for 2–6 seconds at low pressure/flow – helps against channeling and promotes sweetness.
- Pressure: 8–9 bar as a starting point; excessively high pressure can trigger channeling.
Fresh specialty beans and proper storage
Choose beans that match your taste goals and equipment.
- Freshness: 7–30 days after roasting as a starting window; many espressos show their optimum from week 2–6.
- Packaging: Valve bag, airtight after opening. Smaller packages are preferable.
- Storage: cool, dark, dry. Do not store glass containers in sunlight or in humid refrigerators.
- Batch: Weigh out daily portions and seal them tightly to minimize air.
Fine-tuning for Germany: Water hardness, climate and bean selection
Check water hardness and select filtration
The water hardness of the coffee water significantly impacts extraction and the lifespan of the machine. Hard tap water (KH > 6–8 °dH) reduces acidity and sweetness and promotes limescale buildup; very soft water can result in a flat taste and destabilize the extraction process.
- Target range: Total hardness 50–100 ppm, carbonate hardness 30–60 ppm, pH ~7.
- Test: Drop test or analysis by your supplier.
- Solutions: Brita/filter jug, inline filter, ready-made bottled water with moderate mineralization, or remineralization (e.g. bicarbonate/lactate).
Bonus: With stable water , espresso preparation and dial-in become significantly faster and more reproducible.
Humidity and seasons: Influence on grind size
In Germany, humidity and temperature fluctuate considerably. Beans absorb or release moisture – the flow properties of the ground coffee change. A typical consequence: drier in winter, more humid in summer – you need to readjust the grind occasionally.
- Humid days: It's advisable to adjust the settings slightly to a coarser setting (slower flow).
- Dry air from heating systems: Tends to be somewhat finer (faster flow).
- Rule: First check output and time, then adjust in 1-2 clicks.
Even changing beans (new roaster, new variety) requires a mini-dial-in. Note down starting values for each bean – this saves time.
Quick guide: Checklist for consistently good espresso
- Use a scale: dose is exact, output is exact.
- Starting point: 1:2 ratio, 25–30 seconds.
- Grind size: Sour = finer, bitter/dry = coarser.
- Distribution/WDT: Break up clumps, level the surface.
- Tamp: Straight, centered, even. Sieve rim clean.
- Temperature: 92–96 °C, stabilize PID, flush if necessary.
- Pre-infusion: 2–6 s against channeling.
- Water: Medium hardness, constant mineralization.
- Beans: Fresh, suitable for the sieve, and stored correctly.
- Log: Note dose, time, output, taste.
Frequently Asked Questions (FAQ)
Why does my espresso taste bitter?
Bitterness usually results from over-extraction: too fine a grind, too long an extraction time, or too high a temperature. Solution: grind slightly coarser, use a shorter ratio (e.g., 1:2), and check the temperature.
How can I recognize channeling and how can I avoid it?
Signs include splashing, uneven flow, and light streaks in the puck. Prevention: clean distribution (e.g., WDT), even tamping, and a clean shower screen area.
What brew ratio is a good starting point?
For espresso, a tried-and-tested ratio is 1:2 (e.g., 18 g in, 36 g out in 25–30 s). Light roasts often use 1:2.2–1:2.5, darker roasts more like 1:1.8–1:2. Then fine-tune to taste.
What is the optimal temperature for espresso?
The brew group temperature is typically 92–96 °C. Light roasts can tolerate slightly higher temperatures, dark roasts slightly lower. Machines with PID offer the most stable temperature control.
If you want to delve deeper: Try systematic tastings (same bean, three temperatures), keep a simple shot log, and test different water setups. Small, deliberate steps will get you to consistently good espresso faster than big leaps.
5 common mistakes when preparing espresso: causes, influence on taste and solutions
Good espresso depends on precision. Small deviations in grind size, dose, brew ratio , espresso temperature , or tamping quickly add up – and suddenly the shot of espresso tastes too bitter or too sour . In this guide, you'll learn which espresso mistakes are most common, how they manifest in the taste, and which steps reliably help.
Classification: Why small deviations change the espresso
Espresso is an extraction process under pressure. Water successively extracts acids, sweetness, and bitterness from the coffee grounds. The order remains the same – but you control how much of each phase is extracted through grind size, dose, time, temperature, and pressure. Even a slightly too fine or too coarse grind, brewing at too high a temperature, or uneven tamping can throw off the balance.
The goal is consistency: By controlling variables, you can precisely taste the effects of a change. The reward is reproducible results instead of lucky guesses – and the assurance of quickly identifying errors.
The 5 most common mistakes – and how they affect the taste
1. Incorrect grind size: too fine/too coarse
The grind size is the most important factor for espresso . Too fine a grind leads to over-extraction: the shot flows slowly, is dark, dry, bitter, and astringent. Too coarse a grind means under-extraction: the shot flows too quickly, tastes thin, grassy, too acidic , or hollow.
2. Inaccurate dosage and brew ratio
Without scales, there's no consistency: Even a dose of ±0.2 g changes the resistance. The brew ratio (e.g., 1:2) defines how much beverage you extract from the dose. Too high a ratio with the same grind size can emphasize watery, bitter notes; too low a ratio often results in a salty, unbalanced taste.
3. Uneven tamping and channeling
Uneven tamping, lumps in the portafilter, or coffee grounds on the edge of the portafilter create channeling espresso : water seeks the path of least resistance and extracts unevenly. The result: simultaneously under- and over-extracted areas, sputtering, tingling, and a disjointed taste.
4. Incorrect brewing temperature and unstable pressure
The espresso temperature determines how quickly substances are extracted. Too high a temperature emphasizes bitterness, too low an acidity. Unstable pressure amplifies fluctuations. Espresso machines with PID (pulse-controlled temperature) maintain a more stable temperature; without PID, flushing routines and precise timing are necessary.
5. Old or improperly stored beans
Coffee is a fresh product. Old or openly stored beans lose CO₂ and aromatic complexity, extract unevenly, and taste flat, woody, or bitter. Oily, very dark beans age even faster. For specialty coffee and espresso, what matters is: freshly roasted and stored correctly.
Step-by-step solutions: How to avoid these 5 mistakes
Finding the grind size (dial-in) using time and ratio
Start with a 1:2 ratio as a base (e.g., 18 g in, 36 g out in 25–30 s). Adjust the grind so that you achieve the target time in seconds with a constant ratio.
Precise dosing and constant reference quantity
Place scales under the grinder and under the cup. This eliminates fluctuations.
Distribution, WDT and even tamp
Clean distribution prevents channeling. A short WDT (Weiss Distribution Technique) declumps and distributes the coffee grounds evenly.
Temperature and pressure control, flush, pre-infusion
Set your machine to a stable position and ensure reproducible starting conditions.
Fresh specialty beans and proper storage
Choose beans that match your taste goals and equipment.
Fine-tuning for Germany: Water hardness, climate and bean selection
Check water hardness and select filtration
The water hardness of the coffee water significantly impacts extraction and the lifespan of the machine. Hard tap water (KH > 6–8 °dH) reduces acidity and sweetness and promotes limescale buildup; very soft water can result in a flat taste and destabilize the extraction process.
Bonus: With stable water , espresso preparation and dial-in become significantly faster and more reproducible.
Humidity and seasons: Influence on grind size
In Germany, humidity and temperature fluctuate considerably. Beans absorb or release moisture – the flow properties of the ground coffee change. A typical consequence: drier in winter, more humid in summer – you need to readjust the grind occasionally.
Even changing beans (new roaster, new variety) requires a mini-dial-in. Note down starting values for each bean – this saves time.
Quick guide: Checklist for consistently good espresso
Frequently Asked Questions (FAQ)
Why does my espresso taste bitter?
Bitterness usually results from over-extraction: too fine a grind, too long an extraction time, or too high a temperature. Solution: grind slightly coarser, use a shorter ratio (e.g., 1:2), and check the temperature.
How can I recognize channeling and how can I avoid it?
Signs include splashing, uneven flow, and light streaks in the puck. Prevention: clean distribution (e.g., WDT), even tamping, and a clean shower screen area.
What brew ratio is a good starting point?
For espresso, a tried-and-tested ratio is 1:2 (e.g., 18 g in, 36 g out in 25–30 s). Light roasts often use 1:2.2–1:2.5, darker roasts more like 1:1.8–1:2. Then fine-tune to taste.
What is the optimal temperature for espresso?
The brew group temperature is typically 92–96 °C. Light roasts can tolerate slightly higher temperatures, dark roasts slightly lower. Machines with PID offer the most stable temperature control.
If you want to delve deeper: Try systematic tastings (same bean, three temperatures), keep a simple shot log, and test different water setups. Small, deliberate steps will get you to consistently good espresso faster than big leaps.