How to Fix Under Extracted Espresso

As a coffee enthusiast, there's nothing more disappointing than pulling an espresso shot only to realize it's under-extracted. You know the one — it tastes sour, thin, and lacks the rich, complex flavors that make a perfect espresso so satisfying. If you’ve ever found yourself frustrated with your espresso machine, don’t worry — I’ve been there, and I’m here to help you fix under-extracted espresso. Here’s everything I’ve learned through trial, error, and countless shots of coffee.

What is Under Extraction?

Before diving into how to fix under-extracted espresso, it’s crucial to understand what under-extraction is and why it happens. Under extraction occurs when water passes through coffee grounds too quickly and doesn't extract the full range of soluble flavors. This results in a shot that's weak, acidic, and often unpleasantly sour. On the other hand, over-extraction results in bitterness and an overly strong flavor. The goal is to find a perfect balance.

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

• Sour or sharp acidity: This is usually the most obvious indicator. Under-extracted espresso tastes sour, but not in a pleasant citrus way—it’s more of a cringeworthy sourness.
• Thin body: A good espresso should have a rich, syrupy body. If your shot feels watery and lacks depth, it's likely under-extracted.
• Pale crema: Crema should be thick and golden-brown. If it's pale and thin, that's another sign your espresso is under-extracted.

Now that we know the issue, let’s focus on how to fix it by adjusting various factors that impact extraction.

Adjust the Grind Size

Grind size is one of the most critical elements in espresso extraction. Espresso requires a fine grind, but if the grind is too coarse, the water flows through it too quickly, causing under-extraction.

When I began making espresso, I underestimated how much even slight changes in grind size could affect the shot. If your shot tastes sour or thin, the first step is to grind your coffee finer. A finer grind increases the surface area of the coffee, allowing the water to extract more flavors. However, be cautious—too fine of a grind can lead to over-extraction.

Quick Tip: Make small adjustments, one notch finer at a time, and test each shot. You’ll notice a shift in flavor as the grind size gets closer to the sweet spot.

2. Tweak Your Brew Ratio

Another key to fixing under-extracted espresso is adjusting the brew ratio. The brew ratio refers to the amount of coffee grounds compared to the amount of water used. A typical espresso brew ratio is 1:2, meaning 18 grams of coffee should yield around 36 grams of espresso. Under-extraction might result from using too little coffee or too much water.

Experimenting with your dose—the amount of coffee you’re using—can make a big difference. Try slightly increasing the dose to give the water more coffee to work through, which enhances flavor extraction. Alternatively, you can reduce the yield (the amount of espresso extracted) for a more concentrated shot.

When I struggled with under-extraction, adjusting the brew ratio provided remarkable results. If you’re not already weighing your coffee and espresso, now is the time to start. Using a small scale ensures consistency and helps fine-tune your espresso-making process.

Check Your Water Temperature

Water temperature plays a pivotal role in espresso extraction. If the water is too cool, it won’t fully extract the flavors from the coffee grounds, leading to under-extraction. Ideally, the water should be between 195°F and 205°F (90°C to 96°C).

When I first learned about water temperature, I discovered my espresso machine wasn’t hot enough, which explained the sourness in my shots. If your machine doesn’t allow temperature adjustments, ensure it warms up completely before pulling a shot. Some machines take longer to reach the right temperature, so patience is key.

If your machine does have adjustable temperature settings, try raising the temperature a few degrees to improve flavor. However, don’t overdo it—too hot, and you risk over-extraction.

4. Dial in Your Tamp Pressure

Tamping—pressing down the coffee grounds in the portafilter—greatly impacts espresso extraction. If you tamp too lightly, the water will flow through too quickly, causing under-extraction. On the flip side, excessive tamp pressure can lead to over-extraction.

When I first started, I didn’t pay much attention to tamping, but uneven or light tamping can ruin a shot. Ideally, you should apply around 30 pounds of pressure while tamping. It should be firm and even, creating a flat, compressed surface for the water to flow through evenly.

A simple trick is to practice tamping with a bathroom scale. Place your portafilter on the scale and press down with your tamper until you reach 30 pounds of pressure. With practice, you’ll develop a natural feel for the right amount of force.

5. Adjust Your Shot Time

Shot time is another factor that affects extraction. The ideal espresso shot time is typically between 25 and 30 seconds. If your shot is pulling too fast (less than 20 seconds), it’s a clear sign of under-extraction.

If your shot is pulling too quickly, try grinding your coffee finer, increasing the coffee dose, or tamping more firmly. These changes will slow down the water flow, allowing more time for extraction.

Early on, I rushed my shots, unaware that pulling for a few more seconds could make such a noticeable difference. Now, I closely monitor the timer to ensure my shot pulls within the recommended range.

Fresh Coffee Matters

One factor that’s often overlooked in espresso extraction is the freshness of the coffee beans. Coffee begins to lose flavor shortly after roasting, and stale beans won’t yield good results, no matter how perfect your technique is.

I used to hang on to my coffee beans for far too long, not realizing that freshness was critical. Now, I make sure to use beans roasted within the last two weeks, and the improvement is significant. Freshly roasted beans contain more oils and soluble compounds that enhance extraction and flavor.

Conclusion: The Perfect Shot is Within Reach

Fixing under-extracted espresso involves fine-tuning multiple variables: grind size, brew ratio, water temperature, tamp pressure, and shot time. While it can feel overwhelming at first, practice makes perfect, and with time, you’ll understand how each factor influences your shot.

From my own espresso journey, I’ve learned that small adjustments can yield significant improvements. By paying attention to details and practicing regularly, you’ll soon be pulling rich, balanced espresso shots that can rival those from your favorite café. Happy brewing!