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If your morning coffee tastes more like sour fruit than a rich and smooth cup of joe, you may be wondering why it's so acidic. In this blog post, we'll unravel the culprits behind this unpleasant taste and explore the possible causes, from the type of beans used to the brewing method. Get ready to discover solutions to transform your brew and enjoy a more balanced and flavorful cup of coffee!

Understanding Sour Coffee

Sour Vs Bitter Coffee

Sour coffee and bitter coffee are two different experiences that can sometimes be mistaken for one another. Sour coffee is characterized by higher acidity and tanginess, which can be perceived as a zing on your tongue. On the other hand, bitter coffee has a sharp, strong, often unpleasant taste that is usually associated with over-extraction or over-roasting of the beans.

Components of Coffee Flavor

Coffee is a complex beverage with a wide variety of flavors, and understanding its flavor components can help identify the reasons for a sour taste. The main components of coffee flavor include:

  • Acids: Acids are essential in coffee as they contribute to its brightness and liveliness. While good acidity is desirable, an imbalance can lead to sourness. Light roast coffees, for example, often have higher acidity levels, which can lend a pleasant tang but can also create a sour taste if not properly brewed.

  • Sweetness: Primarily derived from the natural sugars in coffee beans, sweetness can balance out acidity and bitterness. An absence or deficiency in sweetness can amplify sourness.

  • Bitterness: Bitterness is an essential part of coffee flavor, balancing the acidity and sweetness. However, excess bitterness can mask sourness or be mistaken for it.

  • Body: The mouthfeel or texture of coffee, body can range from light and delicate to thick and heavy. A strong body can help support and balance sourness.

Causes of Sour Coffee

A sour coffee taste can result from several factors, including:

  • Under-extraction: If coffee is brewed too quickly, the acidic compounds are extracted first, leading to under-extraction and a sour taste. This can be caused by using the incorrect grind size (too coarse) or brewing method.

  • Bad beans: Many factors affect the taste of coffee, including the quality of the beans themselves. Under-roasted beans can taste grassy and sour, while old and stale beans develop a sharp, lemony flavor.

  • Grind size: Using the wrong grind size for the brewing method can greatly impact the taste of the coffee. Coffee that is too coarse for the brew method can result in sour flavors, while coffee that is too fine can lead to bitterness.

  • Brewing technique: Improper brewing techniques such as incorrect water temperature, brewing time or equipment can contribute to sour coffee. Ensuring that each variable is suited to the specific coffee beans and brewing method is essential for a balanced cup.

To prevent sour coffee and achieve a more balanced and enjoyable flavor, experiment with adjusting grind size, brewing methods, and coffee bean quality.

Causes of Sour Coffee


Under-extraction occurs when not enough flavors are extracted from the coffee grounds during the brewing process. This results in an imbalance in the extraction, causing a sour taste. Several factors can lead to under-extraction, including water temperature, brewing time, and grind size. A proper extraction should balance the flavors, resulting in a well-rounded cup of coffee.

Grind Size and Consistency

Grind size has a significant impact on the extraction process. When the grind size is too coarse for the brewing method, the coffee grounds will not adequately release their flavors. This under-extracts the fats and acids, leading to a strong sour taste. To reduce sourness, a finer grind might be necessary. However, a grind that is too fine will lead to over-extraction and bitterness.

Consistency in grind size is also essential for achieving a balanced flavor. When coffee grounds aren't uniform in size, some particles might over-extract, leaving a bitter taste, while others under-extract, causing sourness. Using a high-quality burr grinder ensures consistent grind size and better extraction.

Incorrect Brewing Methods

Choosing the right brewing method plays a crucial role in determining how sour your coffee tastes. Each brewing process has specific parameters for water-to-coffee ratio, water temperature, and brewing time. Incorrectly following these guidelines may lead to under-extraction, which results in sour coffee.

  • Espresso: A typical espresso recipe requires a 1:2 ratio of coffee to water within 25-30 seconds of brewing time. Using a lower water temperature, shorter brewing time, or higher water ratio can cause sour flavors.

  • Drip or Pour Over: For a drip or pour-over coffee, it is essential to use the correct grind size, usually medium-fine to medium. Maintaining a water temperature between 195-205°F (91-96°C) and brewing time of 3-4 minutes is vital to prevent sourness.

  • French Press: A coarse grind is necessary for this brewing method. A proper water-to-coffee ratio, typically around 1:15, along with water temperature between 195-205°F (91-96°C), ensures a balanced cup. Brewing time should be around 4 minutes.

Light roast coffee beans are often more acidic compared to darker roasts, contributing to sour flavors. If you prefer a less acidic coffee, consider using a medium or dark roast coffee bean. Finally, using fresh coffee beans and ensuring they aren't under-roasted can also help minimize sourness in your coffee.

Effects of Roast Profile

Light Roast Coffee

Light roast coffee is typically roasted at a lower temperature and for a shorter amount of time when compared to darker roasts. This results in a retention of more natural acids and complex flavors, giving light roast coffee a brighter taste with higher acidity. Under-roasted beans can sometimes taste grassy or sour, which can be one possible reason for sour-tasting coffee.

When brewing light roast coffee with a French press, it is essential to ensure that the grind size is appropriate for this method, which usually calls for a coarser grind. Additionally, the extraction time should be regulated, as under-extracted coffee may lead to an increase in acidity and a sour taste.

Dark Roast Coffee

Dark roast coffee has a deeper, bolder flavor profile that is achieved through a higher roasting temperature and longer roasting time. This process allows the sugars within the coffee beans to caramelize, which may decrease the acidity when compared to a lighter roast profile. However, if the beans are over-roasted, the oils within the beans can diminish, resulting in a less flavorful and potentially sour-tasting coffee.

Brewing dark roast coffee with a French press may require a slightly finer grind size than light roast coffee, but it is still essential to avoid very fine grinds that can lead to over-extraction and a bitter flavor. Maintaining proper extraction time is also vital to ensure that the coffee does not become sour or overly acidic.

In conclusion, the roast profile can significantly impact the taste of coffee, including the perceived sourness. By understanding the differences between light and dark roasts and adjusting brewing techniques, such as grind size and extraction time, coffee enthusiasts can achieve a desired flavor profile that is balanced and enjoyable.

Water Temperature and Brewing Time

Pour Over Coffee

In pour over coffee, water temperature plays a significant role in extracting the right flavors. It is suggested to use water at a temperature between 195°F and 205°F (90°C and 96°C) for proper extraction. Using water that is too hot or too cold can lead to sour or bitter flavors in the final brew, respectively.

To achieve the ideal brewing time for pour over, it is crucial to control the pouring speed and water ratio. Generally, a coffee-to-water ratio of 1:15 to 1:17 (coffee in grams to water in milliliters) is recommended for optimal extraction. The total brewing time should roughly be between 3 to 5 minutes. If the brewing time is too short, under-extraction occurs, leading to sour-tasting coffee.

Immersion Brewing Methods

Immersion brewing methods, such as French press or Aeropress, also require precise control over the water temperature and brewing time. For these methods, maintaining the water temperature at 195°F to 205°F (90°C to 96°C) is essential, just as it is for pour over methods.

The coffee-to-water ratio for immersion brewing often varies slightly from the pour over method. Generally, a 1:12 to 1:16 ratio works well. However, it's essential to experiment and find the ratio that works best for your preferences.

Brewing time is critical in immersion methods, as it directly impacts extraction. For a French press, a brewing time of about 4 minutes is generally recommended, while the brewing time for an Aeropress varies more, ranging from 1 to 3 minutes, based on the desired coffee strength.

Key Points

  • Maintain water temperature between 195°F and 205°F (90°C and 96°C) for proper extraction in both methods.
  • For pour over coffee, use a coffee-to-water ratio of 1:15 to 1:17 and a brewing time of 3 to 5 minutes.
  • For immersion brewing methods, use a coffee-to-water ratio of 1:12 to 1:16 and a brewing time of 4 minutes for French press, and 1 to 3 minutes for Aeropress.

By following these guidelines, you can prevent sour-tasting coffee and enjoy a well-balanced, flavorful brew.

Improving the Taste of Your Coffee

Choosing Fresh, Quality Beans

One of the primary factors that contribute to sour coffee is the use of stale or low-quality coffee beans. To fix sour coffee, start by selecting fresh, specialty coffee beans from a reputable source. Fresh beans have a richer flavor profile, and their oils have not yet become stale or rancid. Additionally, make sure to store your beans in an airtight container, away from heat, light, and moisture, to help maintain freshness.

Adjusting Grind Size and Extraction

Another reason your coffee may taste sour is due to incorrect grind size and extraction. Under-extraction occurs when water does not have enough contact time with the coffee grounds, which can lead to sour taste. Here are some tips to adjust grind size and extraction:

  • For coarse grinds, such as cold brew or French press, increase the brewing time.
  • For medium grinds, like drip or pour over coffee, ensure you have the right grind size for your specific brewing method.
  • For fine grinds, such as espresso or Aeropress, use a coffee grinder with adjustable settings to ensure the proper grind size.

Note that over-extraction can lead to bitterness in the coffee, so adjust grind size and brewing time accordingly to find the perfect balance.

Refining Your Brewing Method

Each brewing method (e.g., pour over, cold brew, Aeropress) has its own unique characteristics that can affect the taste of your coffee. To improve the taste of your coffee, try refining your brewing technique as follows:

  1. Water temperature: Ensure that the water temperature is within the recommended range for your chosen brewing method (usually between 195°F and 205°F).
  2. Water quality: Use filtered water whenever possible, as tap water can contain minerals and impurities that affect the taste of your coffee.
  3. Brewing time: Experiment with different brewing times to find the ideal balance between under-extraction (sour taste) and over-extraction (bitter taste).
  4. Coffee-to-water ratio: Use a digital scale to measure your coffee-to-water ratio accurately. Generally, a 1:15 to 1:18 ratio (coffee: water) is recommended, but this can vary based on your specific brewing method and personal taste.

By following these tips and experimenting with different brewing techniques, you can significantly improve the taste of your coffee and eliminate the sourness often associated with bad beans, incorrect grind size, and improper brewing methods.

Common Coffee Brewing Mistakes

Using Bad Ingredients

One of the primary reasons your coffee might taste sour is due to bad ingredients, such as poor-quality coffee beans or water with high acidity levels. Make sure to use freshly roasted coffee beans and grind them just before brewing for the best flavor. Dark roasts tend to have lower acidity levels, which could be a preferable option for those sensitive to sour tastes. The freshness of beans is essential since old, stale beans may result in a sharp, lemony flavor that is unpleasant.

Incorrect Brewing Techniques

Another major contributor to sour-tasting coffee is incorrect brewing techniques. For instance, using an immersion brewer for cold brew recipes can result in a subpar flavor. Adjusting the grind size, brewing method, and brewing time can help ensure you get a balanced, satisfying cup of coffee. An under-extracted coffee, caused by too short a brewing time, will lead to a sour taste as the sugars in the beans have not had sufficient time to dissolve in the water. The Specialty Coffee Association suggests there is an ideal water temperature for brewing, which, if not adhered to, can also affect the taste of your coffee.

  • Cold brew: This method requires a longer steeping time with coarse coffee grounds to extract the right flavor compounds.
  • Immersion brewing: For this technique, make sure to use the correct grind size for optimal extraction, generally medium to coarse.

Furthermore, using an incorrect grind size for your brewing method can lead to sour coffee. A finer grind size offers more surface area for the water to extract flavor compounds, while a coarser grind size will require more water or a longer brewing time. Dialing in the grind size and method for your particular taste preferences is crucial for achieving a perfect cup of coffee.

Adjusting to Personal Taste Preferences

It's essential to take personal taste preferences into account when troubleshooting sour coffee. Every individual has unique preferences for their ideal cup of coffee, so consider making the following adjustments to your brewing method:

  • For those who prefer a less acidic taste, try using dark roast coffee beans or adding a little more water to the brewing process.
  • Immersion brewing methods, such as the French Press or AeroPress, can help control extraction time and taste preferences for a more balanced cup.
  • Experiment with the grind size, brewing time, and water temperature until you find the right balance of flavor compounds that satisfy your palate.

By addressing common coffee brewing mistakes, such as using bad ingredients, incorrect brewing techniques, and accounting for personal taste preferences, you should be able to achieve a delicious and balanced cup of coffee that suits your taste buds. Remember, attention to detail and experimentation are key to avoiding a sour-tasting brew.

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Tony Barlow

Tony Barlow

Majesty Coffee Technical Sales Expert - Meet the Team

Tony Barlow, with over a decade of experience in the coffee industry, is the go-to technical sales expert at Majesty Coffee. He's passionate about helping businesses find the right espresso equipment for their needs.

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