Espresso blockage, espresso channel effect, how to do extraction eruption

In general, when coffee machine extraction Italian concentration, the flow rate is a process from slow to fast. Qianjie noticed that some friends would encounter such a situation: after pressing the extraction button, the coffee liquid sprang up directly, and then immediately slowed down, the liquid column gradually became very thin, and the flow rate was completely reversed. Why did this happen?

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Extraction principle of espresso

The espresso machine is much the same as a pressure cooker in that it uses hot water and atmospheric pressure to quickly extract the finely ground coffee powder so that you can get a cup of espresso with rich oil. When we appear the flow rate from fast to slow as described at the beginning, the final probability is that the extraction rate is problematic and the flavor of espresso is general. So we need to find out the cause of this situation and correct it in time.

What are the possible factors that lead to the concentration flow rate "fast first and then slow"? 1. The amount of powder is more than the standard gram weight of the powder bowl when you use more than the standard gram weight of powder, the exhaust space reserved by the powder bowl is filled with powder, and the initial water flow can be carried out by pressure, but the subsequent liquid slows down due to the increase of pressure inside the powder bowl. So when we use the powder bowl, it is best to use the middle value of its standard powder quantity, such as 18-21g in the picture, then we will take 19mur20g of it to make room for its exhaust.

‍ 2, coffee powder filling uneven cloth powder, pressing force center of gravity shift will produce channel effect, let hot water flow out from the place with less resistance first, this will lead to, part of the coffee powder has not been wet, the coffee powder will expand rapidly after being soaked by the current, and the resistance will block the channel. The best solution is that when we fill the powder bowl, we can use auxiliary tools such as powder dispensers to distribute the coffee powder evenly, spread it out everywhere, and then press it evenly (balanced force pressing).

3. Stability of pressure pump

When your pressure setting is too high, it is easy to have a roller coaster extraction range, for example, when the bar value is set to 15, it will be suddenly discharged from the liquid under the pressure of 15bar at the beginning of the extraction, and then suddenly drop to about 9bar. Deep-roasted coffee beans will be easy to extract bad substances. We can solve this problem by adjusting the pressure. The first solution is to reduce the pressure setting and adjust it to the appropriate pressure for the use of beans, such as deep baking can use 9-10bar, shallow ones can be adjusted to a higher level; or we can use pre-soaking when conditions permit, and the details of pre-soaking can be moved to the previous article (how to make pre-soaking), the appropriate adjustment pressure can bring out the appropriate aromatic substances.

4. when the coffee beans are not fresh enough for more than two weeks after the roasting date, the carbon dioxide and volatile aromatic compounds contained in the beans have been gradually discharged, leaving only a small amount of flavor substances in the beans, without the hindrance of gas. water is easy to pass through pressed powder at the beginning, and the flow slows down as pressed powder absorbs hot water and increases resistance. Therefore, Qianjie suggests drinking the beans as much as possible when they are fresh. In the case of more beans, you can use stickers to seal the exhaust valve to reduce exhaust breathing exercise.

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