The principle of step-by-step three-stage extraction of hand Coffee & the Flavor characteristics of Coffee

Guide reading

The joy of hand-brewing coffee is to use different brewing techniques to make coffee have a different soul, of which three-stage extraction is one of the most commonly used methods. When brewing coffee, have you ever thought about the meaning of three-stage water injection?

What is three-stage extraction?

Three-stage extraction is simply to divide the whole water injection process into three parts, including the first stage of steaming. The advantage of three-stage water injection is that the flavor substances of coffee can be extracted more fully during extraction, which can enhance the hierarchical sense of coffee. Why?

Variation of water temperature and powder layer temperature in segmented extraction

Let's think about a question first. Suppose you are using 90 ℃ of water for brewing, is it still 90 ℃ when the water is injected into the coffee powder layer? Qianjie did a segmented water temperature test for this purpose. When the water temperature is 90 ℃, the injection temperature of the first stage is about 86 ℃, the second stage is about 85.3 ℃, and the third stage is about 84.5 ℃.

When the water of different stages and different temperatures is injected into the powder layer, the temperature change of the powder layer is as follows: after the first stage of water injection, the powder layer at normal temperature will rise rapidly (about 86.2 ℃), and the powder layer will greatly cool down (about 78 ℃) after steaming for 30 seconds. After the injection of the second stage of water, the temperature will rise greatly again (about 84.5℃), then drop slightly (about 84 ℃), and the third stage of water will rise slightly again (about 84.3℃).

Seeing here, we can find that although the water temperature of each section is decreasing, the powder layer is heating up in stages. In other words, the powder layer will heat up when water injection, the powder layer will cool down when water injection is stopped, the powder layer will heat up again when water injection is again, and different coffee soluble flavor substances will be extracted at different water temperatures.

What flavor substances are extracted at different temperature stages?

The purpose of the first stage of steaming is not only to let the coffee powder be evenly soaked in hot water and release most of the carbon dioxide, but also the most important step in extracting the sour taste of coffee. Sour substances such as citrus fruits and berries will be released in the first stage.

The second stage is mainly responsible for extracting the sweetness of the coffee, at this stage, less flavor substances are extracted, and the remaining sour substances in the first stage will be extracted in this stage. Sweet substances such as the sweetness of sucrose, the sour and sweet of fruit, and the sweetness of tea will be released in the second stage.

The third stage is mainly the extraction of the mellow substance of coffee, because the water temperature of the third stage is not as high as that of the first stage, so it can effectively reduce some unpleasant flavors, such as wood flavor. The third stage of extraction is mainly to improve the overall mellow feeling of coffee, nuts, cocoa and other charred flavor substances will be released in the third stage.

Three-stage cooking method, how to carry on the section?

In the past, 15g coffee powder was used for daily production in the street, and the proportion of brewing powder and water was 1:15 as an example. First, steam for 30 seconds when using 30g, circle outward at an average [4g/s] speed of [4 seconds / circle] and then return to the center, water injection to 125g cut off water, wait for the powder layer to drop to 1pm, start injecting water to 225g cut off in the same way, remove the filter cup after all the coffee liquid of the filter cup flows into the pot, and then end the extraction.

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