What does hand-brewed coffee mean? How to judge the freshness of coffee beans? How long is the best time to steam with your hands?

"stuffy steaming" can be understood as the preparation for the production of hand-brewed coffee. Because the coffee powder can be better extracted by hot water after steaming. Therefore, steaming is a necessary step for most cooking methods. In addition to allowing beans to be better extracted, the drum phenomenon caused by steaming is also used by many friends as a measure of bean freshness. How do you measure it? For example, in steaming, the bigger the drum bag in the powder bed, the fresher the beans; conversely, the smaller the drum bag in the powder bed, it means that the beans are not so fresh. (the powder bed on the left expands very little)

But! Did you know that the freshness of beans is not the only factor that can affect the size of bulging bags when steaming? For example, in the picture on the front street above, at first glance, the beans on the left are not as fresh as those on the right (because the drum bags are not that big), but in fact, they are both beans baked on the same day! Not only that, their grinding time is only different from that before and after, or steaming at the same time! Then the question arises: apart from the freshness, is there any other reason for the change in the size of the drum bag?

Before answering this question, in order to prevent many beginners from not understanding why the freshness of beans has something to do with drum buns, first of all, let's share the specific role of steaming and why the powder bed bulges when steaming.

What is the specific function of steaming? Coffee beans accumulate carbon dioxide during roasting, which is slowly excreted after the coffee beans are roasted. But before it is fully discharged, the presence of a large amount of carbon dioxide will hinder the hot water's extraction of coffee powder, which is equivalent to an obstacle. Therefore, we need to discharge it through the behavior of steaming. And we have a waiting time after injecting a small amount of hot water, which is a node for carbon dioxide emissions. When the discharge is about the same, we inject a lot of hot water for extraction, which will be better able to extract the flavor substances in the coffee because of the "barrier" (carbon dioxide) loss.

When we understand the above, it is easy to understand why freshness can be linked to the size of drum bags! Carbon dioxide should have dissipated in the air after it was emitted, but because the powder and the powder were linked by hot water, forming a closed space, a large amount of carbon dioxide did not dissipate after it came out of the coffee powder. so you can only be imprisoned in the space formed by the powder bed! Just like balloons, as more and more carbon dioxide is discharged, the whole powder bed gets bigger and bigger! And because the fresh beans contain the most carbon dioxide, the more gas is released during steaming, and the drum bags are therefore bigger. However, when the beans are placed for a period of time, the carbon dioxide dissipates, and then steaming again, it will naturally be unable to form a huge "hamburger" because of the lack of carbon dioxide content (more is the expansion of coffee powder after absorbing water).

To sum up, the size of the steaming drum is related to the freshness of coffee beans because of the amount of carbon dioxide. But! The size of the drum bag can definitely not only be used as a measure of the freshness of beans, because in addition to the freshness, there are many factors that affect the degree of the drum bag, such as extraction efficiency. The reason why we can see the "big bag" standing out of the powder bed in a short time is that the coffee powder gets enough "stimulation". Simply put, there is enough contact between coffee powder and hot water, so that a large amount of carbon dioxide is released in a short period of time.

When we do not use the right parameters, such as coffee beans are not ground fine enough, the water temperature is not high enough, and the flow rate is too fast, which leads to incomplete contact between hot water and coffee powder, these will be because the coffee powder is not "stimulated" enough. as a result, it is impossible to exhaust the gas quickly. Then it will lead to that even a very fresh coffee bean cannot bulge a big "hamburger", just like the picture in front of the street at the beginning! Because the beans on the left use thicker grinding, lower water temperature and faster flow rate of the filter cup, even if the beans are very fresh, they still can't afford big packs! As we often say, the drum bag of shallow baked beans is not as big as that of deep baked beans, and it is also for this reason! Because shallow baked beans are harder, higher extraction efficiency is needed to "stimulate" coffee beans and then achieve a large amount of exhaust, otherwise they will not be able to bulge large bags. At the same time, because the degree of baking is shallow and the coefficient of expansion is not enough, even if it is rich in carbon dioxide, it cannot bulge the same big bag as deep-baked beans.

Then, I believe you can clearly know that the freshness of beans is not the only index that determines the size of the drum bag, as well as the extraction efficiency and the depth of baking.

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