Understanding Acidity in Espresso
Acidity is a complex and desired characteristic in high-quality coffee, contributing to its vibrancy and brightness. However, an unpleasant, sharp, or sour acidity is typically a sign of under-extraction, meaning that not enough of the coffee's flavor compounds have been properly dissolved into the water. The goal is to achieve a balanced extraction, where the pleasing sweetness and bitterness complement the coffee's natural acidity, rather than being overpowered by sourness.
7 Proven Methods to Make Espresso Less Acidic
1. Optimize Your Roast Level
One of the most direct ways to control acidity is by choosing the right coffee bean and roast profile. Lighter roasts tend to retain more of the bean's inherent organic acids, leading to a brighter, more acidic flavor profile. Darker roasts, which are roasted longer and at higher temperatures, have a significantly lower acid content because the roasting process breaks down more of these acids. For a less acidic espresso, opt for a dark roast or a blend specifically designed for espresso. Look for descriptors like "chocolatey," "nutty," or "caramel" instead of "fruity" or "bright".
2. Fine-Tune Your Grind Size
The size of your coffee grind is a critical variable. A grind that is too coarse allows water to pass through too quickly, leading to under-extraction and a sour taste. A finer grind, on the other hand, slows down the water flow, increasing the contact time between the water and coffee grounds. This longer extraction time allows for more of the soluble compounds to be dissolved, resulting in a more balanced and less acidic shot. Adjust your grinder one small step at a time, tasting the shot after each adjustment until you find the sweet spot. A good starting point is a grind slightly finer than table salt.
3. Dial-In Your Brewing Temperature
Water temperature is a key factor influencing extraction. Brewing with water that is too cool can cause under-extraction, amplifying sour notes. The ideal temperature range for espresso brewing is typically between 92°C and 96°C (198°F and 205°F). For darker roasts, a slightly lower temperature within this range may be suitable to prevent bitterness, while a higher temperature can be used for lighter roasts to counteract sourness. If your machine allows for temperature adjustments, experiment within this range. Preheating your portafilter and cups is also essential to maintain a stable temperature throughout the process.
4. Lengthen Your Extraction Time
As noted, a short extraction time is a primary cause of under-extracted, acidic espresso. For a balanced shot, aim for an extraction time of 25 to 30 seconds. A quicker shot means the water hasn't had enough time to extract the desirable sugars and oils, leaving you with a tart, underdeveloped flavor. If your shot is pulling too fast, adjust your grind finer to slow it down. Conversely, if it's running too slow and tasting bitter, a slightly coarser grind will help.
5. Check Your Water Quality
Since espresso is over 90% water, the quality of your water significantly impacts the final taste. Water with a low mineral content (soft water) is more likely to produce an acidic brew. The Specialty Coffee Association recommends water with a specific hardness and alkalinity for optimal brewing. If your tap water is too soft, consider using filtered water with a balanced mineral content. You can test your water's pH and mineral levels with simple strips or opt for a brewing-specific water blend.
6. Adjust Your Brew Ratio
Your brew ratio—the ratio of ground coffee to the liquid espresso output—is another tool for controlling acidity. A common starting ratio is 1:2 (e.g., 18g of coffee to 36g of espresso). If you find your shot is too sour, you can increase the ratio slightly to 1:2.5 or 1:3. This means using a little more water to extract more soluble compounds, which can help balance out the acidity. A longer ratio or a lungo shot can be a simple way to achieve this.
7. Practice and Consistency
Like any craft, making great espresso requires consistent practice. Each variable—bean, grind, temperature, and tamp—affects the others. The best approach is to change only one variable at a time when troubleshooting your shots. Document your adjustments and the resulting taste. This methodical approach will help you pinpoint the precise cause of the acidity and find your perfect settings for any given bean.
Under-Extracted vs. Properly-Extracted Espresso
| Characteristic | Under-Extracted (Acidic) | Properly-Extracted (Balanced) |
|---|---|---|
| Taste | Sharp, sour, and tart, often like lemon or green apple. | Sweet, balanced, with complex notes complementing the acidity. |
| Extraction Time | Too fast, typically under 20-25 seconds. | Optimal, usually between 25-30 seconds for a standard shot. |
| Crema | Thin, pale, and bubbly. | Rich, thick, and caramel-colored. |
| Grind Size | Too coarse, allowing water to pass through too quickly. | Fine enough to create resistance and proper extraction. |
| Body | Thin, watery, and lacking in body. | Full-bodied and rich, with a velvety texture. |
Conclusion: The Path to a Perfect Shot
Achieving a less acidic espresso is an exercise in fine-tuning your entire brewing process, from the initial bean selection to the final extraction. By systematically adjusting variables like grind size, water temperature, and shot time, you can move away from sour, under-extracted shots and towards a balanced, flavorful cup. Start with high-quality, dark-roasted beans and use the other techniques outlined here as a roadmap to your perfect, low-acidity espresso. The journey is part of the enjoyment, and the reward is a consistently delicious and satisfying shot every time.
Additional Resource
For further reading on the science of espresso extraction, check out the Specialty Coffee Association's comprehensive resources on brewing techniques and standards.
