How to Fix Under Extracted Espresso
For true coffee enthusiasts, few things are as disappointing as an under-extracted espresso. That sharp, watery, and lackluster flavor doesn’t deliver the depth and richness a perfectly brewed shot should offer. If you're struggling with under-extraction, don’t worry—you’re not alone. After plenty of trial and error, I’ve learned how to remedy this common issue. Here’s everything I’ve discovered to help you perfect your espresso shots.
Understanding Under-Extraction
Before diving into solutions, it's important to understand what under-extraction is and why it occurs. Under-extraction happens when water flows through the coffee grounds too quickly, extracting too few flavor compounds. This results in a weak, overly acidic espresso that lacks complexity. On the flip side, over-extraction can lead to an overly bitter, harsh shot. The goal is to find the perfect middle ground.
Here are some clear indicators of under-extracted espresso:
Sour or Tart Flavor
One of the most common signs of under-extraction is a sour, sharp acidity. This is not the balanced acidity of a well-brewed shot but an unpleasant, harsh tang.
Watery Texture
A properly extracted espresso should have a syrupy, full-bodied texture. If your shot feels thin and lacks viscosity, it’s likely under-extracted.
Pale Crema
The crema on top of your shot should be thick and golden-brown. A thin, pale crema usually indicates that the espresso wasn’t extracted properly.
Now that you know what under-extraction looks like, let’s explore the steps to fix it. Various factors influence extraction, and adjusting them can help you pull the perfect shot.
1. Fine-Tune the Grind Size
Grind size is one of the most critical factors in espresso extraction. Since espresso needs a fine grind, a grind that's too coarse will cause water to pass through the grounds too quickly, leading to under-extraction.
When I first started, I underestimated how much a small adjustment in grind size could affect the shot. If your espresso is tasting sour or weak, the first thing to do is grind your coffee a little finer. Finer grounds increase the surface area exposed to water, improving extraction. However, be cautious—grinding too fine can lead to over-extraction.
Pro tip: Make minor adjustments, moving the grind just one notch finer, and test each shot. You’ll notice subtle improvements in flavor as you approach the perfect grind size.
2. Optimize the Brew Ratio
Another key factor in espresso extraction is the brew ratio—the balance between the amount of coffee grounds and water used. The standard espresso brew ratio is 1:2, meaning that 18 grams of coffee should yield about 36 grams of espresso. If your shot is under-extracted, adjusting this ratio can help.
I recommend experimenting with the dose of coffee you’re using. Start by slightly increasing the coffee amount, which forces the water to extract more flavor from the grounds. Alternatively, try reducing the amount of liquid yield to concentrate the flavor.
When I struggled with under-extraction, making small tweaks to my brew ratio had a big impact. If you’re not already using a scale to measure both your coffee and shot output, now’s the time to start. It ensures consistency and better results.
3. Adjust the Water Temperature
Water temperature plays a crucial role in espresso extraction. If the water is too cool, it won't extract enough flavor from the grounds, resulting in under-extraction. Ideally, the water temperature should range between 195°F and 205°F (90°C to 96°C).
In my case, I discovered that my espresso machine wasn’t heating the water sufficiently, which was causing sour shots. If your machine doesn’t have adjustable temperature controls, make sure it's fully warmed up before pulling a shot. A little patience goes a long way.
If your machine allows you to control the temperature, try increasing it by a few degrees and see how it affects the flavor. Just be careful not to go too hot, as this can lead to over-extraction.
4. Refine Your Tamping Technique
Tamping—compressing the coffee grounds in the portafilter—is another essential factor. If you tamp too lightly, water will flow through too fast, causing under-extraction. On the other hand, tamping too hard can slow down extraction, potentially leading to bitterness.
In the early days of making espresso, I didn’t focus enough on tamping pressure, and this led to inconsistent results. The ideal pressure is about 30 pounds when tamping. The goal is to create a compact, level coffee puck that allows water to flow through evenly.
To perfect your tamping pressure, you can practice using a bathroom scale. Press down with your tamper until you reach 30 pounds of force, and you’ll quickly develop a feel for the right amount of pressure.
5. Increase the Shot Time
The shot time, or the amount of time it takes for the espresso to brew, also impacts extraction. The ideal shot time for espresso is typically between 25 and 30 seconds. If your shot pulls too quickly—under 20 seconds—it’s likely under-extracted.
To slow down the shot time, try using a finer grind, increasing the coffee dose, or tamping more firmly. These adjustments give the water more time to extract flavors and result in a more balanced espresso shot.
When I first began making espresso, I didn’t realize the importance of shot time. By allowing the shot to pull for just a few more seconds, I saw a significant improvement in flavor.
6. Use Freshly Roasted Beans
An often overlooked factor in espresso extraction is the freshness of your coffee beans. Coffee beans start losing their flavor shortly after roasting, and stale beans can cause even well-prepared shots to taste flat and under-extracted.
In my early espresso-making days, I held onto beans for much longer than I should have. Now, I make sure to use beans that have been roasted within the past two weeks. Fresh beans have more oils and flavor compounds, which contribute to better extraction.
Conclusion: Mastering the Art of Espresso
Fixing under-extracted espresso comes down to fine-tuning a few key variables—grind size, brew ratio, water temperature, tamping pressure, and shot time. While it may seem overwhelming at first, with some practice and patience, you’ll develop a clear understanding of how each factor impacts the quality of your shot. Rather than being discouraged by sour espresso, view it as an opportunity to learn and refine your technique.
In my experience, even small adjustments can yield big results. With careful attention to detail and regular practice, you’ll soon be pulling rich, balanced espresso shots that rival your favorite café. Happy brewing!