What is the reason why espresso extraction is fast or slow? What is the difference between pressing and not pressing? What are the consequences of overheating the cutter head?

One quick, one slow, one good, one bad. Yes, the front street is talking about the occasional instability of espresso when it comes out of the cup. Not only the extraction time is sometimes fast and sometimes slow, but also the taste of the coffee is changeable.

This is a problem that many friends will feel perplexed, obviously the use of grinding, powder are the same, why there is such a big difference in extraction? If this happens to you, it is likely to be caused by the following three reasons! Let's listen to the front street slowly.

First, there is no pressure position "pressure position" and "no pressure position" are two terms that we can often hear! The so-called pressure warehouse is to put more pressure on the coffee beans to be ground, which can be caused by the accumulation of the weight of a large number of coffee beans or from other materials. The non-pressure warehouse refers to only a small amount of beans, the amount of beans is only enough to extract once or several times, and the ground coffee beans will not be suppressed by any pressure during grinding. (for reference only, the left side is the pressure position, the right side is the non-pressure position)

The difference between pressing and non-pressing is not the theme, so Qianjie simply explains here: if you grind the coffee beans after pressing, the coffee beans will not jump at will because of the pressure, and the particles will be more uniform. If the coffee beans are not pressed into the warehouse for grinding, the coffee beans will be easily ejected when they are squeezed and ground by the cutter head, and then fall back and grind again. Over and over again, a coffee bean may be put into grinding many times, and the final grinding particles will be less uniform and thicker. Due to the non-pressure chamber grinding out of the particles are not uniform, and each is different, that for the extraction of extremely sensitive pressurized type is a big change! Then naturally, the state of extraction and the taste of concentration will be affected accordingly.

Therefore, if we need to extract more cups, then it is best to choose to press the position! Put a certain amount of pressure on the coffee beans, the ground particles can be more uniform, so the extraction state is stable. And the pressure warehouse does not necessarily use coffee beans, but also other objects with weight, as long as the package is tight, it is OK.

Second, the cutter head is hot when you continuously produce too many cups and the cutter head works frequently, it will cause the cutter head to get hot. A hot cutter head will crisp the coffee beans you come into contact with, in other words, easier to grind. But this will also make the grains of coffee beans thicker, resulting in a change in flow rate.

In addition, the hot knife plate will also accelerate the loss of flavor substances of coffee powder, because of its high temperature, so the high temperature as the natural enemy of flavor will naturally accelerate the oxidation rate of coffee powder. Therefore, if we are friends who extract at home, in order to ensure the stability of the extraction, then we can choose to slow down the pace of extraction appropriately. If we are friends from the coffee shop, then we'd better adjust the extraction parameters accordingly. (however, dynamic grinding is not recommended, just add and reduce the amount of powder)

Third, another reason for the boiler problem of the coffee machine is the coffee machine. The boiler of the coffee machine chosen by many friends does not support sending milk bubbles and extraction concentration at the same time! Even if it can, it will make the pressure / water temperature provided by the coffee machine during extraction extremely unstable, resulting in a great deviation in the extraction time and the taste of the coffee.

Then the solution to a situation like this is very simple and rough: just do it step by step! First extract and concentrate, and then dispense the foam! In this way, the boiler will not have too much burden in the extraction, and the performance of the extraction will be stable.

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