How to Fix Under Extracted Espresso
For a passionate coffee drinker, few things are as frustrating as an under-extracted espresso. That sharp, thin, and lackluster flavor lacks the depth and richness that make a well-crafted shot so enjoyable. If you’re struggling with under-extracted espresso, don't worry—I've been there too. After lots of trial and error, I’ve learned how to correct this issue. Here’s everything I’ve discovered, step by step, to help you achieve a perfect shot.
What Is Under-Extraction?
Before jumping into solutions, it's essential to understand what under-extraction is and why it happens. Under-extraction occurs when water flows through the coffee grounds too quickly, failing to extract the full range of flavors. This leads to a weak, overly acidic espresso that lacks complexity. On the flip side, over-extraction results in a bitter, overwhelming taste. The key is to strike the right balance between the two.
Here are some telltale signs of under-extracted espresso:
Sour Taste
The most common sign is a sour or sharp acidity, far from the bright, pleasant acidity that enhances a well-pulled espresso.
Thin Consistency
A properly extracted espresso should have a rich, syrupy texture. If it feels watery, it's likely under-extracted.
Pale Crema
A thin, pale crema is another indicator that your shot hasn’t been properly extracted. The crema should be thick and golden-brown.
Now that you know what under-extraction looks like, let's explore how to fix it. Several factors influence extraction, and tweaking these can help you pull the perfect shot.
1. Adjust the Grind Size
Grind size is one of the most crucial factors in espresso extraction. Since espresso requires a fine grind, a grind that’s too coarse will cause the water to pass through too quickly, leading to under-extraction.
When I first started, I didn’t fully appreciate how much a slight adjustment in grind size could change the taste. If your espresso is tasting sour or weak, start by grinding the coffee a little finer. This increases the surface area of the coffee, helping to improve extraction. Just be careful not to go too fine, as that can lead to over-extraction.
Pro tip: Make small adjustments, moving one notch finer each time, and test each shot. You’ll notice gradual improvements in the flavors as you dial in the right grind.
2. Balance the Brew Ratio
The brew ratio, or the balance between the coffee grounds and the water, is another key factor. A common espresso brew ratio is 1:2—for example, 18 grams of coffee should yield about 36 grams of espresso. If your shot is under-extracted, the ratio might need tweaking.
I recommend experimenting with your coffee dose. Start by increasing the amount of coffee slightly, which forces the water to work harder through the grounds and can improve extraction. Alternatively, reducing the amount of espresso in your shot (yield) can concentrate the flavor.
When I struggled with under-extraction, small tweaks to my brew ratio made a significant difference. If you’re not using a scale to measure your coffee and shot output, it’s time to start. Weighing everything ensures consistency and better results.
3. Fine-Tune Water Temperature
Water temperature is another critical component in espresso extraction. If the water is too cool, it won’t extract enough flavor from the coffee grounds, leading to 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 enough, resulting in sour shots. If your machine doesn't have adjustable temperature settings, make sure it's properly warmed up before pulling a shot—patience is key here.
If your machine allows you to adjust the temperature, try increasing it by a few degrees and see if it improves the shot’s flavor. Just be cautious, as too high a temperature can lead to over-extraction.
4. Improve Your Tamping Technique
Tamping, or compressing the coffee grounds in the portafilter, is another factor that affects extraction. If you tamp too lightly, the water flows through too quickly, causing under-extraction. On the flip side, tamping too hard can lead to over-extraction.
In the early days, I didn’t pay enough attention to tamp pressure, which led to inconsistent results. Ideally, you should apply about 30 pounds of pressure when tamping. This creates a compact, even coffee puck that forces the water to extract the flavors evenly.
To practice tamping, use a bathroom scale and press down with your tamper until you hit the 30-pound mark. With practice, you’ll get a feel for the correct pressure.
5. Extend Your Shot Time
Shot time also plays a major role in extraction. The ideal shot time for espresso is between 25 and 30 seconds. If your shot pulls in under 20 seconds, it’s likely under-extracted.
To slow down the shot time, try using a finer grind, increasing the coffee dose, or applying more pressure when tamping. These adjustments will give the water more time to extract flavors and balance the shot.
When I first started making espresso, I didn’t realize how important shot time was. By simply allowing the shot to pull for a few more seconds, I saw a major improvement in flavor.
6. Use Fresh Coffee Beans
One often overlooked factor is the freshness of your beans. Coffee begins to lose its flavor soon after roasting. If you’re using stale beans, no amount of tweaking your technique will save your shot from tasting flat and under-extracted.
In my early espresso-making days, I held onto beans far longer than I should have, unaware of the impact on flavor. Now, I make sure to use beans that have been roasted within the past two weeks. Fresh beans retain more oils and flavor compounds, which significantly improve extraction.
Conclusion: Mastering the Perfect Espresso Shot
Correcting under-extracted espresso is all about fine-tuning the variables—grind size, brew ratio, water temperature, tamping pressure, and shot time. While it may feel overwhelming at first, with practice and patience, you’ll gain a better understanding of how each factor affects your shot. Instead of feeling discouraged by a sour espresso, use it as an opportunity to learn.
In my experience, even the smallest adjustments can make a huge difference. With careful attention to detail and consistent practice, you’ll soon be pulling espresso shots that are rich, balanced, and every bit as good as your favorite café. Happy brewing!