Why Does My Brewed Coffee Taste Sour? Why Is Pour-Over Coffee So Acidic? What Causes Under-Extraction in Coffee?

Recently, an increasing number of friends who previously only drank dark roast coffee have begun exploring acidic light roast coffees. As specialty coffee culture becomes more widespread, everyone wants to experience the graceful floral and fruity notes from their coffee.

However, unlike dark roast coffee, light roast coffee has a much higher probability of brewing failures, so friends often visit FrontStreet Coffee's stores to consult on related solutions. Among these issues, "the brewed coffee is too acidic" accounts for the majority of problems. The reason brewed coffee tastes acidic is primarily because coffee itself contains acidity—this is an undeniable fact. However, many friends report that their issue isn't just that the coffee has acidity, but that the acidity is too sharp and difficult to accept.

FrontStreet Coffee has shared many articles on this topic, but due to the unique characteristics of each coffee bean, universal solutions are not possible. But that's okay! Today, FrontStreet Coffee will share why brewed coffee can taste so sharply acidic. Once we understand the root causes, we can naturally find corresponding solutions!

The Balance of Flavors in Coffee

Besides acidic compounds, coffee also contains other tastes like sweetness, bitterness, and saltiness. Flavors exist in a state of mutual balance. When we feel that the acidity in a cup of coffee is too high, too sharp, or too prominent, this means that acidic compounds have too high a proportion in the coffee, or alternatively, that other flavors have too small a proportion. This causes other flavors to be masked while acidity is amplified, leaving us only able to detect the stimulating acidity from the coffee. As FrontStreet Coffee mentioned earlier, having excessive acidity in a cup of coffee is very common because acidic compounds dissolve fastest during the extraction process.

The Extraction Order of Coffee Flavors

Acidity, sweetness, and bitterness are the three main flavors we extract when brewing coffee, and each has a different dissolution speed! Acidic compounds dissolve fastest, so they dissolve in large quantities at the beginning of extraction, followed by sweetness, and finally bitter compounds. Let me use an example that FrontStreet Coffee often shares: take 5g each of granulated sugar, brown sugar, and rock sugar, corresponding to acidity, sweetness, and bitterness respectively. Then place them in the same cup of hot water simultaneously. Although they start dissolving at the same time, the granulated sugar will dissolve completely in water faster than the others due to its small size and larger total surface area. The brown sugar will be the second to dissolve completely, and finally, the rock sugar with the largest volume will dissolve last. (Cube sugar: pretending to be rock sugar)

Understanding and Solving Sharp Acidity

When we transform this example into coffee extraction and consider the relationship between flavors, we can clearly understand "why coffee tastes so sharply acidic" and "how to adjust it!" If we end the extraction very early, the proportion of acidic compounds in the coffee will definitely be very high, while sweet and bitter compounds will be very few, because the latter two didn't have time to dissolve in large quantities. Therefore, the coffee will taste prominently acidic. However, if we can wait a bit longer or extract more, then with the addition of more sweet and bitter compounds, the proportion of acidic compounds in the coffee will decrease, and the coffee won't taste so acidic!

Practical Solutions for Reducing Acidity

In summary, the solution is obvious: increase the coffee extraction rate. Grinding finer, increasing water temperature, extending extraction time, and increasing water volume are all ways to increase coffee extraction. Among these four methods, extending extraction time and increasing water volume are the most reliable improvement methods, because the former two (under certain specific conditions like very short extraction time or excessive color difference) can easily lead to more acidity in coffee. Therefore, FrontStreet Coffee still recommends prioritizing time adjustment.

For practical brewing operations, light roast, high-density beans can reference this article "How to Brew Light Roast Coffee?" which details how to brew easily clogged light roast beans. For medium-light roast or deeply fermented beans, you can reference this article "Three-Stage Brewing Method." As long as we can control the brewing time within their respective ranges, it will be difficult for the brewed coffee to taste sharply and prominently acidic.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473