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How to Adjust Pour-Over Coffee When It's Too Sour or Bitter? What Causes Overextraction in Black Coffee?

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, In the cupping and tasting system, if a coffee's acidity, sweetness, flavor characteristics, cleanliness, mouthfeel, and aftertaste are all perceived as harmonious, then its balance must be high. This also indicates that the coffee bean's quality is excellent, ultimately earning a remarkable score. When it comes to the brewing process,

In the cupping evaluation system, if a coffee's acidity, sweetness, flavor, cleanliness, mouthfeel, and aftertaste all feel quite harmonious, its balance score will definitely not be low. This also indicates that this bean's quality is excellent, ultimately earning an impressive score.

However, during the brewing process, many influencing factors exist, such as grind size, ratio, water temperature, and others. A slight misstep can disrupt this "balance," resulting in coffee that's either too acidic or excessively bitter. While we may not know which step went wrong, we can be certain that extraction problems occurred. In this article, FrontStreet Coffee will discuss how to quickly adjust when encountering this situation.

Why is Coffee Too Acidic/Too Bitter?

Actually, the taste of coffee we experience is primarily determined by the proportion of acidic, sweet, and bitter flavors—that is, the taste differences caused by the ratio of soluble flavor compounds. For instance, when you drink a very acidic coffee, it doesn't necessarily mean it contains too many acidic compounds; it could be that sweet and bitter soluble components are insufficient to create balance.

What Should You Do if Coffee is Too Bitter?

For most beginners, cases of overly bitter coffee are often related to incorrect grind size. After all, ground coffee exists in a microscopic world measured in millimeters. Unlike other parameters, it's difficult to express with intuitive numerical values, nor can it be compensated for through diligent practice. Therefore, for beginners with limited brewing experience, achieving the right grind is even more challenging.

When the grind is too fine, water encounters greater resistance, making it difficult to flow downward, thereby extending the steeping time and releasing excessive bitterness. Secondly, smaller particles have higher dissolution efficiency, making coffee more prone to overly bitter flavors. For example: when the flow rate is uniform in the first half but becomes increasingly slow in the latter half, with water accumulating in the filter cup, it indicates that the holes are clogged by fine particles. In this situation, the simplest solution is to appropriately adjust the grind to be coarser, using extraction time as reference.

Under ideal conditions, the flow rate of coffee liquid should be consistent, with extraction time around 2 minutes (for 15g of coffee grounds). Of course, some filter cups are designed with inherently slower flow rates, which can lead to longer steeping times during extraction, resulting in predominantly bitter flavors. You can also switch to a faster-draining filter cup, such as a V60.

Unlike sharp acidity in coffee, bitterness is often influenced not just by brewing methods but also by roast degree. Everyone's tolerance for bitterness varies; some find Mandheling not bitter at all, while others think it tastes like "traditional Chinese medicine." Therefore, friends who are naturally more sensitive to bitterness should avoid dark roast coffees described on labels with terms like caramel, dark chocolate, hazelnut, cocoa, or cream. Instead, prioritize light to medium roasts that feature prominent floral and fruit flavors (with acidity).