Over extraction occurs when too many compounds are extracted from the coffee beans, resulting in a loss of flavor and increase in bitterness.
The Extraction Process
The extraction process consists of dissolving sugars, fats, fibers and finally tannins into the water. Too much tannin causes the coffee’s taste to become harsh. As the chemicals have different melting points, controlling timing and temperature during brewing is key.
To avoid over extraction, follow the recommendations for your brew method. Under extraction is the opposite problem, with weak flavor caused by too little dissolution of beans.
Signs of Over Extraction and Solutions
Signs of over extraction include very slow drips, dark uneven frothy crema, dry mouthfeel and bitter taste. The solution is adjusting the grind size or brew time to optimize extraction. Finding the right balance results in a flavorful, aromatic cup highlighting the best qualities of the beans.
Common Mistakes Leading to Over Extraction
- You brew for too long.
- Using water that is too hot.
- Incorrect grind size for your brewing method.
The goal in coffee extraction is balance, aiming for a harmonious interaction of all the parts of a coffee beverage.
Example of Over Extraction
An example of over extraction is a coffee that makes you feel like something is lightly scratching the back of your tongue as you swallow. It’s a clear indication of a bitter taste caused by too many bitter compounds extracted from the beans.
Fixing an Over-Extracted Brew
To fix over extracted coffee try a coarser grind setting or reducing the brew time.
What Causes Over Extracted Espresso?
Too much extraction pressure extracts undesirable compounds from the coffee beans into the espresso. To prevent over-extraction, ensure you have the right grind size, control the brew time, maintain the correct water temperature, adjust the pressure, and use the appropriate coffee-to-water ratio.
Adjustments to Avoid Over Extraction
- Try a coarser grind size.
- Reduce brew time by 30 seconds.
- If using a French press or immersion brewer, reduce brew time.
- Calibrate your equipment regularly.
- If the result is too bitter, dilute with more water or shorten the brewing time.
- Extract more to pull out lower notes for a balanced flavor profile.