What about the astringent coffee? why does the coffee have astringent boutique coffee cup test?

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The astringent taste of coffee is different from the sweet and sour taste, it is not a kind of taste.

Strictly speaking, it should be called "astringency", which is the "roughness" created by polyphenols in food in the mouth.

Polyphenols exist in many kinds of fruits, tea, red wine, chocolate and coffee. Chlorogenic acid, tannin and catechin all belong to polyphenols.

The main source of the astringency of coffee is the "dicaffeoylquinic acid" which is degraded into "dicaffeoylquinic acid" by the "chlorogenic acid" contained in raw beans.

The other part comes from the tartaric acid contained in coffee beans.

The astringency of coffee is related to the variety of coffee beans, the quality of raw beans and the quality of baking technology.

The content of chlorogenic acid in Robusta coffee beans is higher than that in Arabica beans, accounting for 7% of the soybean weight and 10% of the bean weight.

Arabica accounts for only 5.5% of the soybean weight, Murray 8%, so roasting produces more "dicaffeoylquinic acid".

Raw coffee beans of poor quality, especially immature coffee beans, also contain high levels of chlorogenic acid.

If the baking method is incorrect, it is easy to derive more "dicaffeoylquinic acid".

In terms of raw bean quality, there are two main reasons for astringency:

1. Raw bean varieties contain too much chlorogenic acid (such as Luodou and related hybrid varieties)

2. The defect rate of raw beans is too high (such as immature beans and heterogeneous beans)

Astringency is caused by special chemicals in coffee, which can make your mouth and teeth feel dry. The dryness of coffee is usually very similar to the feeling in the mouth when eating raw apples and bananas. But judging from experience, high-quality coffee will never make you feel dry after drinking it.

Generally speaking, the purpose of cup testing of coffee is to determine the flavor of the coffee and decide whether to buy it or how to bake the highest quality of the coffee.

Negative astringency will expose defects in the quality of coffee, but in fact, there is also a good astringency in coffee, and high-quality astringency is sometimes a symbol of coffee quality.

In the baking process, the reasons for astringency are complicated. It is generally believed that the "dehydration period" is too short, that is, the dehydration is insufficient, and the beans (bean core) are not ripe. In addition, according to Master Taguchi, chlorogenic acid stays too long in the process of "water decomposition" and produces excessive caffeic acid and quinic acid, resulting in bitterness.

So, what are the circumstances that usually lead to the astringency of brewed coffee?

In order to eliminate the effect of defective beans on cooking quality, we often encounter sour and bitter conditions in daily cooking. The main reasons are:

1. The water temperature is on the high side (or there is a heat source to heat the water temperature continuously)

2. The water temperature is too low (or the hot water loses temperature too fast)

3. Stirring too much (or too fast)

4. the grinding degree of coffee powder is too fine (or too much ultra-fine powder).

5. The grinding degree of coffee powder is too rough.

If you want to improve the astringency of coffee brewing, try lowering (raising) the water temperature or thickening (fine) the grinding scale. If there is no way to improve after the real adjustment, it may be a problem with the quality and baking methods of the beans.