How to make coffee? a guide for liberal arts students to understand the principle of segmented extraction of hand-made coffee

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Introduction to Qianjie-hand-made Coffee extraction

The first stage of hand-brewing coffee is called pre-soaking or steaming, in which a small amount of hot water is injected to wet the coffee powder, and then wait about 30 seconds. The purpose of this is to remove carbon dioxide.

The gas produced when the coffee beans are roasted will be trapped in the coffee beans, and the coffee will be discharged slowly after baking and when the coffee is brewed. When the coffee powder comes into contact with hot water, the remaining gas will be released, and this process is steaming. The more gas is discharged, the greater the expansion of the steam will be.

There are two main points that steaming contributes to the development of coffee flavor: first, carbon dioxide itself is irritating and sour, which is not pleasant when incorporated into coffee (the sour taste here is different from fruit acid and lively acidity).

Second, when the coffee powder releases gas, the gas interferes with the contact between the coffee powder and water, causing the extraction process to be affected by the gas, which you want to occur in the pre-steaming stage, not in the later stage of the extraction process. Pre-impregnation can reduce the flavor inconsistency of extraction.

2. Extraction

The next stage of hand-brewing coffee is to begin to control the flavor of the brewed coffee. Different chemicals are extracted at each stage of brewing, first the acidity of the fruit, then sweetness, and finally bitterness. (but it is worth noting that not all acids are as pleasant as the acidity of fruit, such as chlorogenic acid produces astringency, dryness and bitterness In this article, we only look at acids that produce positive acidity.

Since different chemicals in coffee can be extracted at different times by hand, you can create your favorite coffee flavor by adjusting brewing methods, and the best way is to control the water temperature and brewing time. Generally speaking, the ideal hand temperature is about 90-96 degrees, which is the most suitable water temperature according to the degree of baking, flavor characteristics, solubility, freshness of beans and grinding thickness.

At this stage, it is very important to cut off the water, that is, the brewer injects the water multiple times. When brewing coffee by hand, it is suggested to reduce the number of times of water cut off and improve the stability of each brew, which removes the human error caused by the barista.

Water cut-off is very important because he believes that water cut-off can lead to more stable and efficient extraction. Because the larger flow and fewer times of water injection will shorten the extraction time, however, multiple injections with small water flow can make the coffee powder bed flatter. The number of times the water is cut off varies according to the nature of the coffee and the grinding thickness.

3. Wrap up

The end of hand-brewed coffee is defined here as the last 40% of the water. Patrik said that this part should be carefully controlled, because the last stage of the extraction will easily release the bitterness and other unpleasant flavors in the coffee, and even if it is done well, the cup of coffee will be ruined by the final over-extraction.

It is suggested that the brewing time and water temperature should be carefully adjusted. In the final stage, fewer substances may be extracted due to the drop in water temperature. Similarly, if you can master the brewing water temperature at this stage, you can create a cup of coffee with a good sense of balance, sweetness and acidity.

If it is a hand flush, the water temperature will certainly drop naturally, but if you are using a coffee machine or a hand machine, you may be able to set the water temperature in stages. It is suggested that different brewing parameters should be set for different coffee, and the water temperature is still the key to affect the sweetness, fruit aroma and balance of coffee.

Knowledge point: it is richer than a knife stream, and it can clarify the flavor of the front, middle and back of the coffee. The method is to increase the amount of water injection each time after steaming, usually when the coffee liquid is about to drop to the surface of the powder layer, and use small, medium and large water flow to do three-stage extraction.

In short: Qianjie is a coffee research hall, happy to share the knowledge about coffee with you, we share unreservedly just to make more friends fall in love with coffee, and there will be three low-discount coffee activities every month. The reason is that Qianjie wants to make more friends drink the best coffee at the lowest price, which has been Qianjie's tenet for 6 years!

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