What is the silver crust of coffee? Does coffee silver skin affect the flavor of a cup of coffee?

I do not know if you have ever encountered, after grinding coffee powder, in addition to brown and black coffee powder, there are also some yellow and white flake debris, these are silver skin. In the face of silver skin, should we remove it or keep it?

What is silver skin?

Silver skin is the last "protective film" of coffee beans. Usually when the coffee beans are processed, the sheepskin (endocarp) will be shaved off, leaving only a thin layer of silver skin wrapped in the coffee beans, which will not fall off until baking.

Different treatment methods for coffee bean silver skin residue is also different, so we can also judge the coffee bean treatment method according to the number of silver skin. The silver skin of sun-treated coffee beans remains more intact in the raw bean state, so the whole piece of silver skin falls off more thoroughly when baking, so there will be less debris of silver skin when grinding. On the other hand, the silver skin of the washed coffee beans is not complete when they are raw, and the silver skin is fragmented and shedding when baking, and some of the silver skins in the middle of the coffee beans are more difficult to fall off, forming a "white line" in the ripe beans. When grinding, these silver skins are also ground into crumbs and mixed into coffee powder.

What does silver skin taste like?

In order to explore the taste of silver skin, Qianjie soaked the silver skin of coffee that fell off during baking in hot water. when soaked, the aroma of the liquid surface is the sweet smell of sweet corn and wheat. The soup is yellowish and transparent. The taste is light sugarcane sweet, and there is no bitterness.

Is it necessary to remove the silver skin?

Although by trying silver skin water, silver skin did not appear too negative taste. So will silver crumbs have an effect on coffee? In this regard, Qianjie intends to make a comparison in the form of a cup test, using coffee beans washed by the Yega Sheffield Ding Ding Cooperative for cup testing, in which one cup blows away the lighter silver skin with an air pump, while the other cup does not do any treatment.

Through the cup test, we found that the two coffee beans, the cup without silver skin did reduce the rough taste, while the control group without silver skin had a rough taste, especially the increase in the number of sips would make the rough taste obvious.

Let's take a look at the comparison of hand brewing, which is also done with Yega Xuefei Ding Ding coffee beans, and one group is treated with silver peel removal. Both groups were cooked in the same way. 15 grams of coffee powder, grindness is 20 standard sieve pass rate 80%, powder-water ratio is 1:15, water temperature 91 ℃. Using Qianjie three-stage cooking, the first stage was injected with 30g water for 30 seconds, the second stage was injected with 95g water, and the last stage was injected with 100g water for 2 minutes.

Through comparison, the flavor of the two groups is basically the same, and there is not much difference in taste, but compared with the two, the flavor of the group without silver dandruff is clearer. In this regard, in the daily brewing, a small amount of silver skin will not have much impact on the coffee, if you want to achieve the extreme, you can blow off the obvious silver skin slightly during grinding.