Knowledge of grinding fineness of popular science coffee

Freshness is the first element of good coffee, and the second important task is to master the roughness and fineness of coffee beans, which directly affects the extraction effect, that is, the quality and intensity of coffee flavor. In principle, the finer the coffee powder, the longer the brewing time, the stronger the coffee flavor; on the other hand, the thicker the coffee powder, the shorter the brewing time, the lighter the taste. The longer the extraction time, the thicker the beans will be ground, so as not to cause excessive extraction and bitterness; the shorter the extraction time, the finer the beans will be ground, so as to avoid insufficient extraction.

For example, the extraction time of a French filter kettle is about three or four minutes, so it is appropriate to grind it roughly, and a household hand-pressed bean grinder (commonly known as a bean chopper or propeller grinder) can be pressed for seven to ten seconds. If it is ground too fine, it is easy to drink coffee grounds and taste bitter. Filter paper or plug bubble cooking method, because the extraction time is relatively short, about one or two minutes, coffee beans have to be ground a little finer than the French filter kettle, about 10 to 15 seconds, but it is best to use a grinder to grind.

Mocha pot is more complex, and the use of heating energy, if it is a gas stove, the heat is more fierce, it is best to grind a little thicker, so as to avoid excessive extraction. It is recommended to use an induction cooker or alcohol lamp, the firepower is easier to control, otherwise the mocha pot is easy to make bitter and strong choking coffee. The extraction time of the mocha kettle is shorter than that of the French filter kettle, filter paper or plug, so the coffee powder should be a little finer, and the grinding time is about 15 to 20 seconds. If the fire source is larger, it can be thicker, the fire source is smaller, and the elastic space is quite large. Summing up the above key points, each bubble method has different extraction time, and the thickness of coffee powder is also different. in principle, the shorter the extraction time is, the finer the particles are, and the longer the extraction time is, the thicker the particles are.

Espresso is served by a double-gear bean grinder.

French filter press, plug air, drip filter or mocha pot do not require high fineness of coffee powder. Knife milk grinder (commonly known as bean chopper or propeller grinder) can not adjust the scale, but to adjust the size of coffee powder according to the length of time, the size of coffee powder is uneven, so it is not suitable for making espresso. It is generally believed that as long as you have an espresso machine, you can make delicious Italian coffee, which is only half right, and the other half depends on a more sophisticated double-gear bean grinder. The lower gear of this bean grinder is connected to a powerful motor, providing a force for high-speed rotation, while the upper gear is connected to the scale and twisted in the reverse clockwise direction, the reading of the scale is getting smaller and smaller, and the upper gear is falling, narrowing the distance between the upper gear and the lower gear. This means that the finer the coffee powder is ground. If the upper gear is twisted in the clockwise direction, the larger the scale value is, the higher the upper gear is and the larger the distance between the upper gear and the lower gear is, so the coffee powder is thicker.

The double-gear bean grinder sets the size of the coffee powder by adjusting each other's height, but don't underestimate this kind of bean grinder. Its structure is extremely precise. Without the double-gear bean grinder, it is impossible to make thick, authentic espresso.

Visual observation of the quality of espresso

Whether espresso is successful or not can only reach 51% accuracy by looking at the flow rate, color or the number of seconds of reading, and it must be tested in person before it is safe. Although the visual method is not very accurate, there is a visual table for reference:

Special features

Insufficient extraction

Perfect extraction

Extraction excess

Extraction time

4-19 seconds

20-25 seconds

26-45 seconds

Fluid pattern

Coarser water injection

It's sticky all the time.

In the shape of water droplets

The color of Klima

Pale to pale

From gold to brown.

Dark brown to scorched black

Klima thickness

Very thin

It is more than 1x3 thick.

Very thin to nothing

Klima firmness

Easy to break

High degree of fit

Easy to break

Aroma and flavor

Lack of energy

Strong, numerous and complex

Sour and bitter