How to solve the perforation phenomenon of Italian concentrated? What is the reason for unstable espresso? Why is the espresso machine extracting fast and slow?

As we all know, one of the most important tasks for baristas when they come to the store every morning is to correct the taste of espresso. Because after a night of standing, the state of the coffee beans has long been changed due to their constant venting characteristics, which will change the extraction time of espresso coffee, which may have an impact on the taste. So in order to keep today's coffee as delicious, baristas correct the concentrated flavor when they go to work in the morning.

In addition to being influenced by the characteristics of the coffee beans themselves, there are many other hidden factors that will affect the extraction of coffee. So not only can we see the change in the outlet status/extraction flow rate of espresso coffee just after a long span of one night, but every few hours, or tens of minutes, we can see the outlet status/extraction flow rate of espresso coffee. The flow rate has changed, either the outlet is fast or the outlet is very slow. However, relatively speaking, these factors do not have such a great impact on taste. But we still need to understand it anyway. After all, it can help us make better adjustments and avoid the emergence of useless efforts. So let's share with Qianjie what other hidden factors will affect the extraction of espresso, and what are their improvement plans. Whether it is a timed bean grinder or a quantitative bean grinder, every time after grinding coffee beans, part of the coffee powder will remain in the bean grinder due to static electricity or structural problems of the bean grinder. In the internal channel. Qianjie has specially measured it before, and the amount of residual powder will be about 1 to 4 g.

When coffee beans are ground into powder, their gas evaporation rate will increase exponentially because the complete structure is destroyed and the total surface area increases. If we do not grind and use this part of coffee powder in a short period of time, the carbon dioxide and aroma substances of the coffee powder remaining in the channel will evaporate over time. If the gas is put into use after it is completely evaporated, it will not only reduce the overall extracted aroma substances, but also affect the extraction flow rate due to the loss of carbon dioxide, causing deviations in the overall extraction.

Therefore, when the interval between grinding coffee powder is too long, it is best to remove the "old" coffee powder remaining in the channel first, and then use the subsequently ground "new" coffee powder for coffee production. This way, the residual powder will not affect the extraction and taste of the coffee ~

2. The water temperature of the coffee machine is the same as that of the bean grinder. When the extraction interval of the coffee machine is too long, it will also have a probability of causing some minor problems that affect the extraction. For example, the temperature of hot water.

In his article two days ago, Qian Jie shared that the temperature of hot water will directly affect the efficiency of coffee extraction. This efficiency not only refers to the dissolution rate of flavor substances, but also the release rate of carbon dioxide. When the water temperature is higher, the more carbon dioxide is released during the same time; when the water temperature is lower, the less carbon dioxide is released during the same time. The amount of carbon dioxide affects the pressure building speed of the coffee machine, so the amount of carbon dioxide released will also affect the extraction of espresso. When the extraction interval of the coffee machine is too long, the temperature of the hot water in the pipe will change, which will affect the extraction of coffee. Therefore, Qianjie recommends that you put hot water in the air before each extraction and concentration, not only to make the extraction more stable, but also to clean away the "coffee residue" attached to the brewing head.

3. In addition to the water temperature, the pressure of the coffee machine will also deviate due to the long extraction interval. Pressure is one of the important extraction parameters of espresso, and its fluctuations will also affect the outflow state of coffee. When we did not extract espresso coffee at an interval of more than 30 minutes, we could clearly feel that the concentrated flow rate of the first extraction would be quite different from the previous one. Even if you used "new powder", hot water was released before extraction, but the flow rate still changed a lot. This is caused by the fact that the water pump has just "woken up" and is still in a trance state.

Generally speaking, the second concentrated extraction will return to normal, but many friends often use the extraction time and taste of the first concentrated extraction as the standard and then make adjustments. As a result, after adjusting several versions, it was found that the coffee extracted from this parameter was the best (Design: I am familiar with this routine). So in this case, we can use the blind bowl to "wake up" the coffee machine's water pump in advance, and then extract the espresso. This will reduce the error caused by the first extraction and allow us to better judge whether the taste and parameters need to be adjusted.

4. Changes in the environment. There is a topic with a very high duplicate check rate in Qianjie's tweet, namely: Why is the concentrate adjustment not good on rainy days? It says that the extraction stability of espresso coffee will be affected by environmental factors, environmental temperature, humidity, air pressure, etc. Because it is described in detail in the blue link, I will briefly summarize it here.

Take environmental humidity as an example first! When the environmental humidity is high, the ground coffee powder will have more "stickiness" and will be more likely to gather together and agglomerate. If the agglomerated coffee powder is directly filled and pressed into the powder bowl without breaking it up, then the powder cake will be more likely to have "channels" due to the presence of agglomerated coffee powder, and the chance of uneven extraction will be greatly increased. Then the air pressure! The air pressure is usually low on rainy days, and coffee machines need pressure to assist in the extraction when extracting espresso. Pressure is generated by the coffee machine relying on a pressure pump, which is the pressure difference relative to atmospheric pressure. However, because the atmospheric pressure on rainy days is relatively low, the reduction in external pressure will reduce the actual extraction pressure generated by the pump. This will make it more difficult for us to steadily extract delicious espresso.

There are many such effects, not necessarily the effects of high humidity environments and rainy days. The impact of environmental change is difficult to control, so we can only correct it in time when there is a problem with coffee extraction (or follow the method in the link). Generally speaking, Front Street recommends correcting the taste of espresso every four hours to ensure continued stability of the product.

5. The warehouse pressure of the bean grinder For the products produced in stores, maintaining the warehouse pressure of the bean grinder is a very important thing. I believe that some friends who often read previous articles will know that the impact of warehouse pressure on extraction cannot be underestimated. The so-called bin pressure refers to the downward pressure formed by the accumulation of coffee beans in the bean bin.

When coffee beans are being ground, the existence of a certain chamber pressure will improve the grinding quality of the coffee beans, and the ground particles will be more uniform. If the coffee beans are not pressed by weight when being ground, then they will easily bounce when being crushed! This will greatly reduce the uniformity of grinding and reduce the quality. If stores want to maintain stable production, it is best to control the capacity in the bean warehouse to more than half. Or you can use other heavy objects (such as books) and press them on top of the coffee beans after sealing and dustproof packaging ~

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