Is it important to extract espresso powder? Does it have a great influence on the extraction of coffee liquid?

The thickness of the powder controls the speed at which water passes through the coffee powder, and when the thickness of the powder is the same, different states of the powder layer will produce different passing speeds.

The action of beating powder, beating powder will make the fine powder sink, and the distribution of coffee powder will be more hierarchical, coarse at the top and thin at the bottom.

And knock too much, even if the same thickness, the flow rate will become slower, fine powder accumulates at the bottom, the resistance becomes greater.

And the strength of the powder is a factor that determines that the water stays and then the coffee powder is of the same thickness. It does not determine the overall flow rate.

This is not easy to understand.

According to common sense, the greater the pressure, the stronger the pressure.

The actual coffee beans are naturally distributed and pressed after grinding, and the structure of the powder layer is not changed. Can only change the surface state of coffee powder.

Then why press it? Here I say that the extraction of espresso cannot be uniform. Because the water will always find a place with relatively little resistance to go down.

At present, no bean grinder is absolutely uniform, all relatively uniform.

Therefore, to press this action is actually to let her stay longer on the surface, so that the surface resistance is close to the same, so that the coffee can be extracted more evenly.

Rotating when pressing powder can change the structure of the powder layer.

It can make the powder stick together more closely to improve the water resistance of the coffee powder layer.

The beans are ground to Italian thickness, and the appearance of the powder is more irregular. Give it a rotating drive on the surface, and the powder that fits each other will get stuck in one place, resulting in increased resistance to water, making it more uniform when it passes through coffee.

So, do you think pressing powder is useful? I say it is useful to increase the time for the water to stay on the surface of the coffee.

But please think of this as a variable.

Baristas all know that when using an espresso machine, the hot water brewed has about 9 atmospheric pressure (of course, this is not a fixed value, there are 12 atmospheric pressure or higher), and the pressure is very high, when the water penetrates the coffee cake. the water is inert. What is inertia, that is, water will penetrate through the weakest part of the coffee cake, not from the thickest place.

Therefore, if you do not use a coffee powder press to compact and flatten the coffee (to make the density of the coffee powder in the powder bowl as uniform as possible), the essence of the coffee will not be extracted, or some parts will be overextracted.