How to Fix Under Extracted Espresso

As a coffee enthusiast, there's nothing more disappointing than pulling a shot of espresso only to find it under-extracted. You know the feeling—thin, sour, and lacking that rich, balanced flavor you were hoping for. If you've ever experienced this, don't worry! I've been there, too, and through trial and error, I've learned how to fix under-extracted espresso. Here's what I've discovered along the way.

What is Under Extraction?

Before we get into the solutions, let’s define under extraction and why it happens. Under extraction occurs when the water flows through the coffee grounds too quickly, not giving enough time to fully extract the flavors. This leads to a shot that tastes sour, weak, and lacks depth. In contrast, over-extracted espresso tends to be bitter and too strong. The key is finding the right balance between the two.

Signs of under-extracted espresso include:

• Sour or acidic taste: This is usually the most noticeable sign.
• Thin body: Instead of the rich, syrupy texture you expect, the shot feels watery.
• Pale crema: The crema is light and thin, rather than thick and golden-brown.

Now, let’s explore how to correct under-extraction by adjusting various factors in your brewing process.

1. Adjust the Grind Size

One of the most crucial factors in espresso extraction is the grind size. Espresso needs a fine grind, and if your grind is too coarse, the water will pass through too quickly, leading to under-extraction.

When I first started making espresso, I underestimated how much small changes in grind size could affect the shot. If your espresso is sour or thin, the first step is to make your grind finer. A finer grind increases the surface area of the coffee, allowing the water to extract more flavors.

Tip: Adjust your grinder in small increments, testing each shot as you go. Small changes can make a big difference, so take your time to find the sweet spot.

2. Tweak Your Brew Ratio

The brew ratio—the ratio of coffee grounds to water—plays a significant role in espresso extraction. For a typical espresso, the ratio is around 1:2, meaning you use 18 grams of coffee to pull about 36 grams of espresso. If your shot is under-extracted, you may be using too little coffee or too much water.

Try increasing the dose slightly or decreasing the yield. This gives the water more coffee to extract flavors from, leading to a more balanced shot.

I found that weighing both my coffee dose and my espresso yield helped me achieve more consistent results. A small scale can be a great investment to help you dial in the perfect shot.

3. Check Your Water Temperature

Water temperature is another crucial factor in espresso extraction. If the water is too cool, it won't extract enough flavor from the coffee grounds, resulting in under-extraction. The ideal water temperature for espresso is between 195°F and 205°F (90°C to 96°C).

If you’re using a machine without adjustable temperature settings, make sure to allow the machine to warm up fully before pulling a shot. If your machine does allow for temperature control, try increasing the temperature slightly to see if it improves your extraction.

When I first realized my machine was brewing too cool, increasing the temperature by just a few degrees made a big difference in the flavor of my espresso.

4. Refine Your Tamping Technique

Tamping is the process of compressing the coffee grounds in the portafilter before brewing. If the grounds are tamped too lightly, water will pass through them too quickly, causing under-extraction. On the other hand, tamping too hard can lead to over-extraction.

The ideal tamp pressure is around 30 pounds. You want to apply firm, even pressure to create a level surface for water to flow through evenly. If you’re unsure how much pressure you’re using, practice with a bathroom scale to get a feel for it.

Early on, I didn’t pay enough attention to my tamping technique, which caused inconsistent results. Once I developed a consistent tamp, my shots became much more reliable.

5. Adjust Your Shot Time

The ideal shot time for espresso is usually between 25 and 30 seconds. If your shot pulls too quickly, it’s likely under-extracted. A shot that pulls in less than 20 seconds often tastes sour and weak.

To slow down the shot, try grinding the coffee finer, increasing the dose, or tamping more firmly. These adjustments will give the water more time to extract the flavors from the coffee.

When I started timing my shots, I was surprised by how much just a few extra seconds could change the taste of my espresso. Keeping an eye on shot time is essential for consistent results.

6. Use Fresh Coffee Beans

One often overlooked factor in under-extracted espresso is the freshness of the coffee beans. As coffee beans age, they lose their flavor and oils, which are essential for good extraction. Stale beans can make it almost impossible to pull a well-extracted shot.

I used to keep my beans for too long, not realizing how much freshness impacted my shots. Now, I make sure to use beans roasted within the past two weeks, and the difference in flavor and extraction quality is significant.

Conclusion: Mastering the Perfect Shot

Fixing under-extracted espresso is all about making small adjustments to variables like grind size, brew ratio, water temperature, tamp pressure, and shot time. Though it can seem frustrating at first, with practice, you’ll start to understand how each factor impacts your final shot.

In my espresso-making journey, I’ve learned that these fine-tuning steps can lead to noticeable improvements. By paying close attention to these details and practicing regularly, you’ll soon be pulling rich, balanced shots of espresso that rival your favorite café. Don’t be discouraged by a sour shot—use it as a learning opportunity to improve your technique. Happy brewing!