How fine espresso coffee powder is correct | how fine it takes to make espresso powder.

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The thickness should be proportional to the extraction time.

The fineness of coffee grinding will directly affect the extraction time and extraction rate. The finer the coffee is ground, the denser the powder layer is, the more coffee powder is in contact with hot water, the greater the extraction resistance is, the easier it is to prolong the extraction time and increase the extraction rate, so it is easy to over-extract. On the contrary, the coarser the coffee powder is, the larger the gap in the powder layer is, the less coffee powder particles are in contact with hot water, and the weaker the extraction resistance is, the more difficult it is to prolong the extraction time, and reduce the extraction rate, which is easy to be insufficient. Therefore, the finer the coffee is ground, it will prolong the extraction time and increase the extraction rate; the coarser the coffee powder is, it will shorten the extraction time and depress the extraction rate.

Under normal conditions, the fineness of coffee is inversely proportional to the extraction time and extraction rate. This can be proved by hand brewing and espresso. The coarser the powder, the smaller the extraction resistance, the greater the coffee flow, the shorter the extraction time, the lower the extraction rate, and the lighter the taste. On the contrary, the finer the powder is ground, the greater the extraction resistance is, the smaller the flow rate is, and the longer the extraction time is, the higher the extraction rate is and the stronger the flavor is.

Deep baked beans are slightly thicker, shallow baked beans are slightly thinner.

In addition, before deciding on coffee bean grinding, coffee veterans will first look at the color and oil production of cooked beans. The lighter the roasted coffee, the more complete and hard the fiber is, the more difficult it is to extract. It is appropriate to use fine grinding, but it should not be too fine, so as not to highlight the sharp and sour taste. The deeper the roasting degree of coffee, the deeper the damage to the fiber, the easier to extract, it is appropriate to use slightly rough grinding, deep roasting grinding too fine will be bitter. Therefore, the degree of grinding of deep-roasted coffee is generally thicker than that of shallow roasted beans.

The thickness can control the bitterness

Roughness is a good way to control bitterness, because the finer the grinding, the higher the extraction rate, the easier it is to extract high molecular weight bitter substances such as chlorogenic acid, quinic acid, caffeine and carbonization. On the contrary, if the grinding is too rough, the lower the extraction rate is, the more difficult it is to extract the astringent bitter substance with high molecular weight, but the sweet taste with middle molecular weight may remain in the coffee grounds because of insufficient extraction, which is a waste. Therefore, baristas should pay attention to whether the thickness of the powder is normal every day. Too thick or too fine will cause abnormal extraction and affect the flavor of coffee.

The degree of grinding of all kinds of bubble cooking methods, from coarse to fine, in the following order:

French filter kettle (rough grinding) > electric trickling filter pot (medium) > hand punch pot, siphon pot (medium) > mocha pot (medium) > espresso (fine) > Turkish coffee (very fine).

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