Why Is Extraction Time So Important for Pour-Over and Espresso Coffee?

The Importance of Time in Coffee Extraction

Many coffee beginners, when first starting out, focus intensely on controllable factors like grind size, water-to-coffee ratio, water temperature, and brewing techniques. However, "time"—this uncontrollable factor—is often overlooked. In reality, it plays a crucial role in crafting a great cup of coffee.

Soluble Substances in Coffee Beans

Let's first discuss the soluble substances contained in coffee beans. In a single coffee bean, only 30% consists of soluble flavor compounds, while the remaining 70% is insoluble woody fiber. It's similar to chewing gum—when you've extracted all its soluble flavor, what remains is tasteless "woody residue"!

Although there are 30% soluble flavor compounds, we don't need to extract all of them! We only need to extract 18-22% to achieve optimal results.

The Three Types of Soluble Flavor Compounds

We can categorize the soluble flavor compounds in coffee beans into three types: acidic substances, sweet substances, and bitter substances. Each substance has different dissolution rates—simply put, each substance reaches its peak release at different time periods during extraction.

Acidic substances have the fastest dissolution rate, so they reach their peak release at the beginning of extraction, emerging in large quantities! Next come sweet substances, whose dissolution rate is slightly slower than acidic substances. When acidic substances are being released in large quantities, sweet substances dissolve gradually, only reaching their peak release during the middle stage of extraction. Bitter substances have the slowest dissolution rate. As we can see from the graph, initially, the release of bitter substances is nearly parallel to the horizontal axis—extremely slow. It only begins to increase its dissolution speed when sweet and acidic substances reach their peak release!

Therefore, in general, the longer the extraction time, the more substances are dissolved, resulting in coffee with richer flavors and more distinct layers!

The Importance of Timing in Extraction

The reason we need to pay attention to time is to control the amount of these substances being released! This ensures balance between different flavors. For example: when extraction time is too short, before reaching the point where sweet substances are released in large quantities, the entire cup of coffee will lack the support of sweet and bitter flavors, becoming thin and sharply acidic—resulting in "under-extraction." On the other hand, if extraction continues until bitter substances are released in large quantities, bitterness will dominate, and the entire cup of coffee will be immersed in negative, astringent flavors—resulting in "over-extraction"!

Therefore, we need to stop the extraction of soluble substances after sweet substances have been released in large quantities but before bitter substances reach their peak release. This way, we can achieve a cup of coffee with balanced acidity, sweetness, and bitterness!

The best method is to control the timing. For pour-over coffee using 15g of beans, with normal parameters, simply controlling the extraction time between 1 minute 50 seconds and 2 minutes 25 seconds will yield a coffee with balanced acidity, sweetness, and bitterness!

Common Misconception

Now that we've covered the main topic, let's address an important misconception regarding the release of acidic, sweet, and bitter substances! People often mistakenly believe that these substances are released sequentially! In reality, acidic, sweet, and bitter substances are released simultaneously from the beginning. However, due to their different dissolution rates, they have different peak release points—and this is where the misconception lies.

For instance, when we drink coffee extracted from light roast beans, although it's difficult to perceive bitterness, bitter substances are indeed present—they're just masked by the acidic and sweet substances due to their relatively small quantity!

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