How to Fix an Under-Extracted Espresso

For coffee lovers, few experiences are as disheartening as pulling an under-extracted espresso shot. That sharp, thin, and unappealing flavor lacks the depth and richness that a well-crafted espresso should offer. If you’re facing issues with under-extraction, don’t fret—I’ve been there too. After extensive trial and error, I’ve learned effective methods to address this problem. Here’s a comprehensive guide based on my experiences to help you achieve the perfect espresso shot.

Grasping Under-Extraction

Before we delve into solutions, it’s important to understand what under-extraction is and what causes it. Under-extraction occurs when water flows through the coffee grounds too quickly, failing to extract the full range of flavors. This results in a weak and overly acidic shot that lacks complexity. On the flip side, over-extraction leads to bitterness and an overpowering taste. The key is finding the right balance between the two.

Here are some telltale signs that your espresso is under-extracted:

Sour Taste

One of the most noticeable indicators is a sour or sharp acidity, which is far from the bright and pleasant acidity that enhances a well-made espresso.

Watery Consistency

A properly extracted espresso should have a rich, syrupy mouthfeel. If your shot feels thin or watery, it’s likely under-extracted.

Weak Crema

The crema on your espresso should be thick and golden-brown. A thin, pale crema is a clear sign that the extraction process was inadequate.

Now that we know how to identify under-extraction, let’s discuss how to remedy it. Several factors influence extraction, and adjusting these can help you pull the perfect shot.

1. Adjust the Grind Size

Grind size is one of the most critical elements of espresso extraction. Since espresso requires a fine grind, using a coarser grind will allow water to pass through too quickly, leading to under-extraction.

When I first started making espresso, I didn’t realize how much a slight adjustment in grind size could impact the flavor. If your espresso tastes sour or weak, start by grinding the coffee a little finer. This increases the surface area of the coffee, promoting better extraction. Just be careful—not grinding too finely 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 flavor as you hone in on the right grind.

2. Reevaluate the Brew Ratio

The brew ratio, which is the balance between coffee grounds and 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, this ratio may need adjustment.

I suggest experimenting with your coffee dose. Start by slightly increasing the amount of coffee, which forces the water to work harder through the grounds and can improve extraction. Alternatively, reducing the volume of espresso produced can concentrate the flavor.

During my own struggles with under-extraction, I found that small tweaks to my brew ratio made a significant difference. If you’re not already weighing your coffee and shot output, it’s time to start. Weighing ensures consistency and enhances results.

3. Optimize Water Temperature

Water temperature plays a crucial role in the extraction process. If the water is too cool, it won’t extract enough flavor from the coffee, leading to under-extraction. Ideally, the water temperature should range from 195°F to 205°F (90°C to 96°C).

I discovered that my espresso machine wasn’t heating the water adequately, resulting in sour shots. If your machine doesn’t have adjustable temperature settings, make sure it’s fully warmed up before pulling a shot—patience is essential.

If your machine allows temperature adjustments, try increasing it by a few degrees and observe how it affects the flavor of the shot. Just be cautious, as too high a temperature can lead to over-extraction.

4. Perfect Your Tamping Technique

Tamping, or compressing the coffee grounds in the portafilter, is another factor that influences extraction. If you tamp too lightly, water will flow through too quickly, causing under-extraction. Conversely, tamping too hard can slow down the extraction process.

In the early days, I didn’t pay enough attention to tamping 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 allows the water to extract flavors uniformly.

To practice tamping, consider using a bathroom scale and pressing down with your tamper until you hit the 30-pound mark. With practice, you’ll develop a feel for the correct pressure.

5. Extend the Shot Time

Shot time also plays a major role in extraction. The ideal shot time for espresso typically falls between 25 and 30 seconds. If your shot pulls in under 20 seconds, it’s likely under-extracted.

To lengthen the shot time, consider using a finer grind, increasing the coffee dose, or tamping with more pressure. These adjustments will give the water more time to extract flavors, resulting in a more balanced shot.

When I first started making espresso, I underestimated the importance of shot time. By allowing the shot to pull for just a few extra seconds, I noticed a significant improvement in flavor.

6. Ensure Your Beans Are Fresh

One often-overlooked factor is the freshness of your coffee beans. Coffee begins to lose its flavor shortly after roasting. If you’re using stale beans, no amount of technique adjustment will rescue your shot from tasting flat and under-extracted.

In my early espresso-making days, I held onto beans for longer than I should have, unaware of the impact on flavor. Now, I ensure that I use beans roasted within the past two weeks. Fresh beans retain more oils and flavor compounds, significantly enhancing extraction.

Conclusion: Achieving the Perfect Espresso Shot

Correcting under-extracted espresso involves fine-tuning several variables: grind size, brew ratio, water temperature, tamping pressure, and shot time. While it may seem overwhelming initially, with practice and patience, you’ll gain a clearer understanding of how each factor influences your shot. Instead of feeling discouraged by a sour espresso, consider it a valuable opportunity to learn and grow.

In my experience, even minor adjustments can lead to significant improvements. 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 those from your favorite café. Happy brewing!