For coffee lovers, few things are more disappointing than sipping a shot of under-extracted espresso. A thin, sour brew that lacks the depth and richness of a well-made shot can ruin the entire coffee experience. If you’ve encountered this issue, you’re not alone. Fortunately, by making a few adjustments and experimenting with your technique, you can fix this problem. Based on my personal experiences, here’s a comprehensive guide to help you craft the perfect espresso shot every time.
What Causes Under-Extraction?
Before we dive into solutions, it's important to first understand what under-extraction is and why it happens. Under-extraction occurs when water passes through the coffee grounds too quickly, failing to extract enough of the coffee's natural flavors. The result is an espresso that lacks complexity, often tasting flat or sour.
When brewing espresso, water needs to be in contact with the coffee grounds for a sufficient amount of time to extract the oils, acids, and other compounds that contribute to a balanced and flavorful shot. If the water passes through too quickly, it pulls out only the more acidic, unpleasant flavors, leaving behind the full-bodied sweetness and richness we crave in a perfect espresso shot.
How to Identify Under-Extraction
There are several ways to identify under-extracted espresso, and paying attention to these details can help you troubleshoot the issue and find solutions quickly.
1. Excessive Sourness
One of the first signs of under-extraction is overpowering sourness. While espresso does have an inherent acidity, it should be balanced, not sharp or unpleasant. If your shot tastes excessively sour, it’s a sign that the water didn’t extract enough of the coffee’s soluble compounds. Instead, you’re left with the more acidic notes, which dominate the flavor.
2. Watery Texture
Espresso should have a full, creamy consistency with a velvety texture. If your shot feels thin or watery, this is another clear indicator of under-extraction. When espresso is under-extracted, the water doesn’t have enough time to interact with the coffee grounds, resulting in a weak and watery brew rather than a rich, concentrated shot.
3. Faint Crema
The crema on top of a well-made espresso should be thick, golden, and stable, indicating a rich and balanced extraction. In contrast, an under-extracted shot will have a weak, pale crema that fades away quickly. This happens because there are fewer oils and solids extracted from the coffee, leaving the crema to be thin and short-lived.
How to Fix Under-Extracted Espresso
Now that we understand what under-extraction is and how to identify it, let’s explore some practical solutions. The key to fixing under-extracted espresso is making small adjustments to several variables that influence the extraction process. These include grind size, brew ratio, water temperature, tamping pressure, and shot time.
1. Adjusting Grind Size for Better Extraction
Grind size plays a crucial role in espresso extraction. If your grind is too coarse, water will flow through the coffee grounds too quickly, leading to under-extraction. The goal is to slow the water down just enough for it to extract the full range of flavors from the coffee.
When I first started making espresso, I didn’t realize how much a small change in grind size could impact the shot’s flavor. To improve a sour or watery espresso, experiment with a finer grind. A finer grind increases the surface area of the coffee, allowing the water to extract more flavor. This adjustment can make a significant difference in the taste and texture of your espresso.
Pro Tip: Make small adjustments to the grind size and test each shot to find the ideal balance. It’s important to understand that grinding too fine can lead to over-extraction, which can result in bitter flavors. So, you’ll need to find a grind size that’s just right for your espresso machine and your taste preferences.
Products to Try:
- Baratza Encore Conical Burr Coffee Grinder – A reliable, entry-level grinder that offers consistent grinds for espresso brewing.
- Capresso Infinity Conical Burr Grinder – Another excellent option for consistent grind sizes, especially for espresso brewing.
2. Adjusting Brew Ratio
Another factor to consider when fixing under-extracted espresso is the brew ratio—the amount of coffee grounds to water. If you’re using too little coffee or too much water, the result can be under-extracted espresso.
Typically, espresso is brewed using a ratio of 1:2 or 1:2.5, meaning for every gram of coffee, you should aim to extract between 2 to 2.5 grams of liquid espresso. If your shot is too thin or sour, it could be due to a ratio that’s out of balance.
To correct the brew ratio, start by using the recommended amount of coffee for your espresso machine, usually between 18 to 20 grams for a double shot. If you’re brewing a single shot, use around 9 to 10 grams of coffee. Ensure that your shot yields a proportional amount of espresso—this should ideally be around 36-50 grams of liquid for a double shot.
Pro Tip: If you consistently get under-extracted shots, try increasing the amount of coffee grounds or reducing the amount of water to get the balance right.
3. Water Temperature
Water temperature plays a significant role in espresso extraction. The optimal temperature for brewing espresso is between 190°F and 200°F (88°C to 93°C). If your water is too cold, it can lead to under-extraction, as the water won’t be able to dissolve the coffee’s soluble compounds effectively.
Most modern espresso machines have temperature controls, so make sure your machine is set to the right temperature range. If you’re using a machine without temperature controls, consider using an external thermometer to measure the water temperature before brewing.
Pro Tip: If you notice your espresso is consistently sour, try increasing the water temperature slightly, but be careful not to go too high, as this can lead to over-extraction and bitterness.
Products to Try:
- Breville BES870XL Barista Express Espresso Machine – A great home espresso machine with adjustable temperature controls and a built-in grinder.
- Rancilio Silvia Espresso Machine – A sturdy and reliable espresso machine for home use that maintains a consistent water temperature.
4. Tamping Pressure
Tamping is the process of compressing the coffee grounds into the portafilter to create an even puck. If your tamp is too light or uneven, it can cause uneven extraction, which leads to under-extracted shots. A proper tamp ensures that the water flows through the coffee grounds uniformly, which is essential for consistent extraction.
When tamping, apply firm, even pressure to compress the coffee grounds. I find it helpful to use a tamper that fits the portafilter well and provides a good grip. Aim for a tamping pressure of around 30 pounds of force, though this can vary depending on the specific grind and machine you’re using.
Pro Tip: After tamping, give the portafilter a gentle tap on the counter to settle the coffee grounds and eliminate any air pockets. This ensures a more even extraction.
Products to Try:
- Rattleware Espresso Tamper – A high-quality tamper with a flat base for an even tamp every time.
- Motta Professional Espresso Tamper – Known for its solid construction and ergonomic handle for consistent tamping pressure.
5. Shot Time
Shot time refers to the amount of time it takes for the espresso to be extracted. If the shot is too short, it may indicate that the coffee grounds are too coarse or that the tamping pressure is too light. On the other hand, if the shot takes too long, it could mean that the grind is too fine, leading to over-extraction.
A typical espresso shot should take between 25 to 30 seconds to brew. If your shot is pulling too quickly or too slowly, adjust the grind size, tamping pressure, or brew ratio accordingly.
Pro Tip: Use a timer to measure the extraction time for each shot. If your shot is under-extracted, increase the shot time by making the grind finer or increasing the tamping pressure.
Conclusion: Attaining Espresso Excellence
Fixing under-extracted espresso requires adjusting several variables, such as grind size, brew ratio, water temperature, tamping pressure, and shot time. While it may seem overwhelming at first, with practice and attention to detail, you can achieve consistency and master the art of espresso making.
From my own experience, it’s often the smallest adjustments that lead to the most noticeable improvements. By focusing on these key factors, you’ll soon be able to pull espresso shots that are rich, well-balanced, and as satisfying as those from your favorite coffee shop.
The key is experimentation, patience, and continuous learning. Don’t be discouraged if your first few attempts aren’t perfect. Keep refining your technique, and you'll be able to enjoy the perfect espresso shot in no time.
Happy brewing!