Why did the powder bed break in two after making coffee? What information is hidden in the powder bed of hand-brewed coffee?

Including Qianjie, many friends have a habit when they first start, which is to observe powder pits after making coffee. Why? Because we can see from the "state" of the powder pit whether there is any part of our brewing that needs to be corrected. If the state of the powder pit is bowl-shaped and the powder wall is complete and has uniform thickness, it means that our water injection method during the brewing process is relatively standardized and there are no problems to pay attention to; if there is an "abnormality" in the powder pit, such as uneven and the powder wall is potholed, it means that our water injection method is relatively not standardized and may need to be corrected. Because although irregular water injection may not necessarily make the coffee difficult to drink, it also has a certain probability that it can reduce the quality of the coffee. For example, the powder pit state in the figure below is a good example.

We can clearly see that although the powder wall of this powder pit has been built to a sufficient height, a fault has appeared where the powder wall connects with the bottom of the powder pit. It looked like the entire powder bed had been cut in half and split into two. This is a phenomenon that many friends often complain about with Qianjie! Even if they follow the tutorial to brew and inject water, the final appearance of the powder bed will always appear in this state of being "cut in half". The coffee tasted slightly worse. It wasn't that it tasted bad, but it wasn't that good.

Usually this phenomenon occurs because water is directly injected on the powder wall, which leads to no coffee powder in the places where it is washed. This is exactly what many friends are curious about, because they obviously did not flush water directly onto this pink wall, but why would this happen?

Why did the powder bed break in two after making coffee? This is a quite interesting phenomenon. In the article "Hand-brewed Coffee Powder Pit Collection" shared before Qianjie, there is a pink wall in this form. There are two reasons for the appearance of this pink wall, which usually occurs at the end of multi-stage brewing. One reason is that hot water was directly injected on the powder wall mentioned above, causing the coffee powder on the powder wall to be washed down; the other reason is that the penetration of the water column is too high.

When the height of water injection is too high, or the water injection flow is too large, the water flow will have a strong penetration. In this case, even if we do not flush the water to the edge of the filter cup, the water will still have too high penetrating power and directly break through the powder wall hidden under the water, resulting in the phenomenon that the powder bed will be cut in two. The emergence of this phenomenon will reduce the extraction rate and concentration of the obtained coffee (probability, but not small), because part of the hot water that breaks through the powder wall will directly fall into the lower pot, forming bypass water. Not only does it reduce the amount of extracted substances, but it also directly dilutes the concentration of the already extracted coffee. Therefore, the appearance of this kind of pink wall not only means that we have not injected water reasonably, but also means that the quality of coffee has a probability of declining.

How to avoid powder bed faults? The adjustment method is very simple. There are two methods to choose from, and we can decide based on the current brewing situation. The first adjustment plan is to narrow the circle of water injection, so that no matter how hard the water injection is, you don't have to worry about breaking through the powder wall, because the hot water will rush to the thickest part of the powder bed. Take Qianjie as an example. When Qianjie uses three-stage brewing, it will concentrate the hot water from the last stage in the center and inject it into it. It also needs to be circled, but the width of the circle is only the size of a coin. The purpose of this is not only to ensure that hot water does not break through the powder wall to form bypass water, but also to increase the extraction rate of the coffee powder at the bottom, so that the extraction of coffee is more uniform and the flavor performance is more complete.

The other way is to reduce the intensity of the injected water flow. Since the powder wall is broken because the penetration power of the water flow is too strong, can't we just reduce the intensity of the water flow? As mentioned in the previous street, the penetration of the water flow is affected by the water injection height and the water injection rate. When the water injection height is higher and the water flow is greater, the penetration of the water flow will be stronger. On the other hand, if we want to reduce the penetration of water flow, we only need to reduce the height of water injection or reduce the water flow.

When making coffee, Qianjie usually maintains the height of the water column at about 3 to 4 cm (close to the height of a fist), but it is not because it is the best to make coffee at this height, but because it is the smallest chance of making coffee at this height. In other words, it is relatively conservative! This height not only ensures that the water column can provide sufficient stirring rate, but also does not have too strong penetration to promote the generation of bypass water. It is easier to use and is very suitable for novices when they are just getting started. Finally, Qianjie still needs to emphasize one point: whether the powder pit is beautiful or not does not directly prove whether the coffee is delicious. It can only show a general water injection path during the brewing process, so it is best not to rely solely on the powder bed. The appearance of the bed makes a judgment on the taste of coffee. However, when we found that the brewed coffee was not as delicious as usual, it could become another detail in addition to parameters that could determine the problem. So Qianjie means that everyone can drink coffee first, and when the taste of the coffee is not up to standard, we can find out the problem according to the parameters and the appearance of the powder bed ~

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