What is the astringent taste in coffee? Is astringent taste or taste? How to adjust the sourness and bitterness of hand-brewed coffee?

"astringent" is a resident "player" in coffee. It is a taste, not a taste. The sour and bitter we often talk about is a feeling produced by the astringent feeling combined with the taste of coffee. Whether the coffee is mellow or not, we may not be able to tell it in the first place. But the coffee is not astringent, we can detect it directly. Because the astringency and other aspects of the taste, there is a big difference!

Taste descriptions such as mellow and light describe the amount of coffee liquid in the mouth. Astringency, on the other hand, refers to the rough feeling caused by the coffee liquid in the mouth. Negative feelings such as numbness, dryness, or unsmoothness of the tongue can be classified as astringency. The reason for the astringency of coffee is mainly due to the release of too many polyphenols from coffee beans. Chlorogenic acid, tannic acid and other substances are the main contributors to astringency (chlorogenic acid is the most important). When these substances come into contact with our saliva, they react with proteins in the saliva membrane, which in turn reduces the lubricity of the saliva itself. Lubricity mainly plays a role in reducing friction! So when the lubricity of saliva attached to the tongue is reduced, the friction of the tongue will increase, and when the coffee enters the mouth, it will have more friction with the tongue, and then be perceived by us, and this is the so-called astringency.

In addition to astringency, chlorogenic acid is also a contributor to sour and bitter taste, so most of the time the astringency does not appear alone, it will evolve into sour or bitter together with bitter or sour taste. Because most of the substances that cause astringency belong to macromolecules and the dissolution rate is relatively slow, generally speaking, when there is an obvious negative astringency in the coffee, it means that the cup of coffee is in a state of underextraction or overextraction. In most cases, astringency will be caused by over-extraction, such as overbrewing green tea, which will have a terrible sense of astringency. We can solve the problem by reducing the extraction efficiency.

Of course, the astringency is not all bad. High-quality astringency will not hide the flavor and taste of coffee, it will appear shallowly after the flavor performance, so that we can feel the existence of astringency but does not affect other feelings, so it is quite a multi-level performance, but often this kind of astringency is very few.

In addition to the effect of brewing, the astringency may also come from the coffee bean itself. In addition to the excessive release of polyphenols from coffee due to brewing errors, the coffee bean itself may also have an astringent taste because of too many of these substances. There are two situations that can lead to excessive polyphenols in the coffee bean itself. one is to pick the coffee bean when it is not ripe, then the coffee bean it handles will not be able to produce too many other substances because it is not ripe. Lead to astringent substances "stand out".

The other is that the degree of coffee roasting is too shallow, the internal development is insufficient, and there is a state of entrainment. In the same way as sour and bitter taste, the shallower the baking, the more astringent substances will be retained. Both cases will make the coffee itself astringent, because the beans themselves are rich in polyphenols, and the coffee will naturally behave accordingly. So you can know why the coffee fruit is picked all red, and why the beans can't be roasted too shallow (low fault tolerance rate) ~

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