Why Does Pour-Over Coffee Often Become Over-Extracted and Bitter? Causes and Solutions for Coffee Over-Extraction

In the world of pour-over coffee, there are often friends who describe themselves as "masters of over-extraction" (meaning they've mastered various brewing methods that lead to over-extracted coffee).

Of course, if a cup of coffee is described as "over-extracted," it definitely means that some undesirable flavors have emerged in the coffee. Typically, an over-extracted coffee will exhibit burnt or harsh bitterness, but not all uncomfortable bitterness can be attributed to over-extraction. For example, brewing coffee too strong can also create an uncomfortably intense bitterness, which doesn't qualify as over-extraction.

Understanding Over-Extraction

Let's first understand the mechanism of over-extraction. This concept originates from the familiar Golden Cup extraction standards. Through research, Dr. Lock found that only 30% of substances in coffee beans are water-soluble, and when the extraction rate falls between 18-22%, coffee tastes best. When coffee develops unpleasant bitterness, extraction rates are typically above 22%. Gradually, "over-extraction" became the term used to describe coffee with that harsh, unpleasant bitterness.

To this day, research continues into whether improved coffee quality can allow extraction rates above 22% to still taste good. Therefore, when you hear someone mention over-extraction today, they're not necessarily saying the coffee extraction exceeded 22%, but rather that they've detected that burnt, harsh bitterness.

Causes of Over-Extraction

The primary reason for coffee over-extraction is excessively high extraction efficiency. When broken down into specific brewing parameters, this manifests as: water temperature too high, coffee ground too fine, too much water poured, extraction time too long, or overly vigorous water pouring and agitation.

Nearly any method that increases coffee extraction rate can potentially lead to over-extraction.

Ultimately, it comes down to either an unreasonable brewing recipe or a brewing method that demands high technical skill from the brewer, resulting in low fault tolerance. For example, when watching world-class pour-over competitions, you'll see some competitors using highly personalized brewing recipes. Some recipes pursue极致 coffee flavors and require considerable technical skill and understanding from the brewer, making them less fault-tolerant. Improper brewing can easily produce harsh bitterness.

Brewing Parameters and Balance

It's difficult to determine reasonableness from any single parameter alone. Take grind size, for instance: some people use a coarseness similar to raw sugar, while others use a fineness like table salt. With pouring techniques, some prefer gentle water pouring, while others like rapid circular agitation of the coffee bed. Looking at any single parameter in isolation, we can't say that raw sugar coarseness is correct and table salt fineness is wrong, or that gentle circular pouring always tastes good while rapid agitation causes over-extraction. All parameters must be considered together to determine whether the brewing approach is reasonable.

FrontStreet Coffee's Approach to Brewing

In developing brewing recipes, FrontStreet Coffee prefers to use methods with high fault tolerance. For example, in water temperature selection, FrontStreet Coffee typically uses 91°C. This temperature offers high fault tolerance for many coffee beans and can accommodate other harder-to-adjust parameters (such as grind quality). When there are fewer fine particles, brewing at 93°C can yield fuller, richer flavors. However, if there are many fine particles, continuing to use 93°C can easily develop harsh bitterness. By using 91°C, the flavors might not be as rich when there are fewer fine particles, but in situations with many fine particles, brewing at 91°C is less likely to produce over-extracted flavors. This demonstrates high fault tolerance.

The same principle applies to circular pouring, coffee grind size, and water ratio selection. Choosing parameters with high fault tolerance can maximize the avoidance of many undesirable flavors.

Important Notice :

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