Why is the source of astringent coffee astringent? how to solve the problem of sour and bitter coffee

When we drink coffee with astringent taste, we first think that it is caused by excessive extraction of coffee as a whole... but this is not 100%, and it may be caused by one of the too long steams/post-extraction ~

Why does coffee taste bad?

What kind of feeling is astringency? When we taste a food, as if there is something rough through the tongue surface (tongue numbness/dry feeling) and produce a smooth feeling, it is astringent performance. When we feel coffee astringent/astringent, most of the time it comes from polyphenols or acids in coffee.

The former is the majority ~ When polyphenols (chlorogenic acid, tannic acid and other antioxidant compounds in coffee beans) come into contact with our saliva, these compounds will cause proteins in the saliva film to react, which will reduce the lubricity of saliva. Loss of saliva lubrication, coffee substances will be more friction with the tongue surface, so there is a tingling/dry feeling ~ and acid compounds (citric acid and other organic acids) will reduce the pH value of the oral cavity, thus stimulating the nerves on the oral mucosa and feedback to the brain: "Hey! This guy's got a bad rap."

How can we tell which extraction stage coffee astringency comes from?

Everyone will feel the astringency of coffee, but they will not judge whether the astringency comes from excessive extraction in the front or excessive extraction in the back, so when there is astringency, we need to carefully judge the feeling of tongue and throat ~

If you feel a rough feeling on your tongue and a dry throat at the same time, most of the time it is caused by excessive extraction. When the concentration of polyphenols and acids is too high, both will stimulate the organs and tissues used in the whole swallowing process. This situation is probably caused by the long extraction time. We can shorten the coffee extraction time by adjusting the coarse grinding degree/changing the water injection size/changing the number of water injections.

If only one of the tongue roughness/throat dryness is felt, it may be the unpleasant feeling caused by the high concentration of one of the polyphenols/acids, so that one compound stays in the tongue/throat for a longer time. In this case, we need to consider adjusting the extraction time of the previous stage or the latter stage, that is, shortening the steaming time/pinching the tail stage.

In addition to brewing effects, astringency may come from coffee beans ~

Of course, the above is only on the level of coffee brewing, and the appearance of astringency may also be a problem with the coffee beans themselves. One is that coffee beans themselves produce more polyphenols/acids due to variety and planting environment;

One is that coffee beans are underdeveloped when roasted, just like fried steak. The outside is charred and the inside is tender ~ the surface of coffee beans has begun to caramelize, but the inside of coffee beans is still medium ripe, so that coffee tastes green.

There is also a situation that has nothing to do with coffee beans and brewing.

Your tongue is dehydrated!

When dehydration occurs on the tongue surface, you will feel numb/rough on the tongue after drinking water. Most of this happens after you have eaten salty foods (such as soy sauce, fish sauce, etc.)/drunk a lot of alcoholic drinks before you taste coffee. This causes the oral epithelium to contract so that whatever passes through the tongue "rubs relentlessly" against the surface.