Taming the Tang: Why Your Espresso Tastes Sour and How to Fix It
Espresso, when brewed correctly, is a beautiful balance of sweetness, bitterness, and just a touch of acidity. But when your shot leans too far into sour territory, it can be an unpleasant experience—one that leaves your taste buds puckering and your cup unfinished. A sour espresso is often a sign that something in the brewing process is off. The good news? It’s usually easy to fix once you identify the cause. Let’s explore what might be going wrong and how you can bring your espresso back into balance.
Under-Extraction: The Most Common Culprit
Sourness in espresso is typically the result of under-extraction—when the water doesn’t spend enough time in contact with the coffee grounds to pull out all the desirable flavors. The first compounds to extract are acidic ones, followed by sweet and bitter notes. If the process stops too early, you’re left with mostly acidity and very little balance. Short brewing time, too coarse a grind, or not enough pressure are all possible causes.
Grind Size: Too Coarse Means Too Sour
Espresso requires a fine grind to ensure the water extracts a full range of flavors. If your grind is too coarse, water flows through the puck too quickly, resulting in an under-extracted, sour shot. Try adjusting your grinder one step finer and test again. Small changes can make a big difference, and dialing in the right grind is one of the most important steps to improve flavor.
Brew Time: Too Fast Equals Too Tart
A good espresso shot typically takes about 25 to 30 seconds to extract. If yours is coming out in under 20 seconds, there’s a good chance it’s under-extracted. This can be due to grind size, but also tamping pressure or insufficient coffee dose. Watch the flow rate and aim for a slow, steady stream resembling warm honey.
Water Temperature: Too Cool to Extract Fully
Water that’s too cool—below 195°F (90°C)—won’t extract enough from the coffee, resulting in sharp, acidic flavors. Most espresso machines are calibrated to brew at around 200°F (93°C), but if yours isn’t heating properly or you’re using a manual method, it could lead to sourness. If possible, test the water temperature and ensure your machine is fully preheated before pulling a shot
Coffee Beans: Light Roasts Bring More Acidity
If you’re using a very light roast, especially a single-origin bean from regions like Ethiopia or Kenya, a bright, citrusy flavor is often part of the bean’s natural profile. In this case, the sourness may be intentional—but it shouldn’t be overwhelming. Consider trying a medium roast or a blend for a more balanced espresso, especially if you’re new to brewing.
Machine or Grinder Issues
Inconsistent pressure, temperature, or burr alignment in your grinder can cause uneven extraction. If you’ve tried adjusting the basics and sourness persists, it might be time to inspect your equipment. A poorly calibrated machine or grinder can sabotage even the best beans and techniques. Regular cleaning and maintenance are essential to consistent performance.
Conclusion
A sour espresso may seem like a mystery at first, but it’s almost always a sign of under-extraction or brewing imbalance. By refining your grind size, adjusting your brew time, checking water temperature, and choosing the right beans, you can transform that overly tangy shot into a rich, flavorful espresso. With a little experimentation and attention to detail, your next cup can hit the sweet spot—literally.
