Coffee extraction time is bitter and sweet-American coffee extraction time

In the usual Italian grinding case, the cube of 1cm will be crushed into hundreds of small particles, and you should be able to imagine how the extraction area of coffee will be multiplied. With the rapid increase in the surface area of coffee extraction, it becomes easier for water to dissolve most of the flavor substances in coffee.

In these hypothetical small cubes, there are a large number of flavor substances that can not be immediately touched by water. This is why thicker coffee powders take more time to extract than finer ones: it takes some time for water to get inside these thicker coffee powders, which are then dissolved and transported to external solvents. When it comes to fine powders, all the water has to do is touch them, and everything will be dissolved. With this comparison, you should be able to understand how important the extraction area is in increasing extraction.

The most important thing I want to tell you here is that the thickness of coffee powder does not change the substance being extracted. The only thing it does change is when these substances are extracted. All the flavor substances are there from beginning to end, and they have been preserved in coffee beans waiting to be extracted. Grinding finer or thicker just allows water to come into contact with more or less flavor substances in the first place.

We can also think differently about the extraction area: when we think about how to adjust the degree of grinding, we are actually thinking about "how many coffee flavor substances do you want to hide away from water contact?" or "what percentage of flavor substances do you want to be delayed?" . The finer powder can hide less flavor, which will reduce the delay effect, while the thicker powder will hide more flavor substances and enhance the delay effect.

Increasing the contact area between coffee and water makes it easier for water to extract flavor substances. When you grind the coffee into powder, the surface area of the coffee increases exponentially.

You can think of coffee beans as a cube with 1cm sides, with six faces, each with an area of 1cm ², so the surface area of this cube is 6cm ².

Cut the cube in half and then in half. Until you get eight small cubes. At this point, the side length of each small cube is 0.5cm, the surface area is 1.5cm ², and the total area of the eight small cubes will be 12cm ², which increases the surface area that water can contact. It didn't take long for us to double the extraction area.

Then let these small cubes undergo a rough grinding to get 64 small cubes with side length of 0.25cm. The surface area of a single small cube is 0.375cm2, and the total surface area becomes 24cm2. It's doubled again!