Grindability and extraction Progress of hand-brewed Coffee

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Earlier on, I saw a Taiwanese barista in Youtube explain why the coffee powder is thicker but the coffee brewed is more bitter. Contrary to the theory, I think it is worth thinking and discussing and tidying up the article. Sorry, I forgot to keep a record of the clip. You are welcome to supplement the video link.

In the film, the barista sifted the coffee powder with two degrees of grinding, divided it into three kinds of coarse and young degrees, and compared the cloth of the coarse young powder under the two degrees of grinding. In contrast, the group with rougher grinding degree, as expected, had more coarse particles, but there was no significant decrease in fine powder. The distribution can be understood as shown in the following figure:

The first group is called Reference Grind Size, the red part is fine powder, which is the main source of bitterness, green is medium thick, can be understood as contributing sweet part, yellow is coarse powder, the more this part, the more sour the coffee.

The second group was thicker (Coarser Grind Size), green medium powder decreased, instead of yellow coarse powder increased, red fine powder did not significantly decrease.

The taste of coffee requires a balance between sweet, sour and bitter. It can be inferred that, by comparison, the coffee made by the second group of coffee powder is more sour and less sweet than the first group, even though the objective bitterness (assuming it can be measured by machine) is about the same, but due to the lack of sweetness balance, the coffee of the second group will be more sour and bitter than the first group. This phenomenon runs counter to the theory of "adjusting roughness to acid, adjusting youth to thickening". The next step should be to explore the principle of fine powder formation, in order to explain why adjusting the degree of grinding can not reduce the amount of fine powder.

It can be seen that coffee brewing is true by taste, and the scientific nature of coffee lies in the experiment. The correct direction should be to refine the theory from the experiment and promote new fields based on the theory, rather than clinging to the theory and sticking to the rules.

Text: knowledge of Ken

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