What is the definition and purpose of steaming hand-brewed coffee? Why can't hand-brewed coffee steam make a big bag? What is the impact of steaming and steaming of hand-brewed coffee? Why is the steaming drum of deep-roasted coffee bigger?

Whenever Qianjie makes a customer's order by hand, as long as the bulge on the powder bed is relatively large during steaming, there is a certain probability that the guest and friend will ask: "Why is the bulge on the powder bed when I make coffee not so big? "

This is a topic that Qianjie often shares! To make sense, although the bulge size during steaming does not directly reflect the taste of coffee, we can read a lot of other information from its status, such as the status of the coffee beans or the parameters used during brewing, because it is they that determine the bulge degree of the flour bed. So today Qianjie will come to share with you how these factors affect the degree of bulging, and then why the size of the bulging cannot directly reflect the taste of coffee.

1. The freshness and roasting degree of coffee beans First of all, we need to know that the main reason for the bulging phenomenon when steaming coffee is caused is carbon dioxide. Coffee beans accumulate a large amount of carbon dioxide during roasting, which will be slowly released after the coffee beans are roasted. If coffee ground comes into contact with hot water, the emission rate of these carbon dioxide will be greatly accelerated. What we call steaming is a step specifically designed to emit carbon dioxide. By using a small amount of hot water to wet the coffee powder, carbon dioxide will quickly transfer outward, which allows the hot water we inject later to better extract the flavor substances in the coffee.

In the process of carbon dioxide emission, the surface tension of water molecules and the capillary action between coffee powder particles will weave an airtight "barrier." The reason why it is airtight is that this "barrier" will "confine" carbon dioxide in the powder bed and cannot be discharged. Due to being "imprisoned," carbon dioxide will accumulate more and more in the powder bed, and then the powder bed will bulge bigger and bigger like a balloon due to the increase of air in the body. And this is the principle of powder bed bulging. Through this principle, we can know that the main reason for the bulging of the powder bed is the influence of carbon dioxide, and the carbon dioxide content of coffee beans is one of the factors that determines the size of the bulging. With the same extraction parameters, the more carbon dioxide the coffee beans contain, the greater the degree of bulging during steaming; the less carbon dioxide, the less the degree of bulging.

In fact, it is easy to understand, because the more carbon dioxide content of beans, the more carbon dioxide will be emitted during steaming, so the bulging of the powder bed will naturally be improved due to the increase of carbon dioxide. There are two main factors that determine the carbon dioxide content of coffee beans: roasting degree and freshness. As the coffee beans are fresher/deeper they are roasted, the more carbon dioxide content will be, and vice versa.

So if the coffee beans we use are roasted deep enough or fresh enough, then we can see relatively larger bulges when steaming. But careful friends should have discovered that Qianjie has always emphasized a premise in the above, that is,"under the condition that the extraction parameters remain unchanged." Why? -- Because extraction parameters are another factor that affects the size of the drum!

2. The extraction efficiency during brewing should be accurately the extraction efficiency! The more efficient the extraction we use when brewing, the more quickly the substances in coffee will be dissolved, including carbon dioxide. Therefore, the higher the extraction efficiency, the faster the carbon dioxide will be released, and the greater the degree of swelling of the powder bed will be at the same time.

The reason why many friends 'powder beds cannot bulge when steaming is because the extraction efficiency during steaming is not high enough, which prevents carbon dioxide from being released quickly in a short time. So even if the beans used are very fresh or deeply baked, the degree of bulging is not that outstanding. What everyone needs to know is that although there are many factors that affect the extraction efficiency, such as time, grinding, stirring, water temperature, etc. However, when steaming, the main factors affecting the size of the drum are the water temperature and the thickness of the grinding. The higher the water temperature and the finer the grinding, the greater the degree of bulging during steaming, and vice versa.

To sum up, you can know that the main factors that affect the size of the bulge during steaming of the coffee powder bed are the freshness, roasting degree, and extraction efficiency during brewing. But again, the size of the drum does not directly reflect the taste of coffee! For example, the Qianjie Boundary Estate·Xizhao in the Qianjie Bean List last time, Qianjie used the same parameters to compare the Xizhao that was brewed and baked for 2 days and the Xizhao that was baked for 25 days. Although fresh Chinese claw baked for 2 days will have a larger bulge than Chinese claw baked for 25 days, its flavor is not as rich.

Although the Chinese claw baked for 25 days does not bulge when steaming, its layers are rich and prominent. In terms of flavor, in addition to the flavors of grapes, passion fruits, apricot peaches, and wine aroma, Qianjie also drank a little floral fragrance and a more rounded fruit wine aroma. The reason for this difference is that excessive carbon dioxide, which is often mentioned in the front street, hinders extraction, but since it is not the main content of this article, I will not go into it too much here. Therefore, it is best not to use the bulging size of the powder bed during steaming as a measure of the taste of coffee, because this does not directly reflect the taste of coffee. It still reflects the status of the coffee beans mentioned earlier on the street., brewing parameters, it will be more appropriate for us to regard the bulging degree as a "file" of these two pieces of information to read ~

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