Where did the sour in the coffee come from? Why is the coffee so sour?

Coffee contains a variety of ingredients, extraction is not to extract all of these ingredients, there is usually such a rule: if the amount of coffee powder is fixed, the amount of extraction of soluble ingredients is determined by grinding degree and time.

The finer the grinding degree of coffee powder is, the longer the extraction time is, the more ingredients will be obtained. According to the experiment, if all the ingredients that can be extracted from the quantitative coffee powder are extracted, up to 30% of the ingredients can be extracted. But not all of these ingredients are what we need. Coffee has ingredients that we need as well as ingredients we don't need, and the longer it takes to extract, the easier it is to extract bad ingredients that we don't need.

One of the most important ingredients we do not need is "tannin", the correct name should be called tannic acid. Raw coffee beans contain 8%-9% and roasted raw beans contain 4%-5%. Like caffeine, it has the property of being decomposed at certain baking degrees. When baked to a depth around French or Italian baking, 90% of the tannins are broken down.

Most people will think that deep-roasted coffee is strong and light-roasted coffee is weak, this idea is completely wrong, mistakenly thinking that light-roasted coffee is less irritating, and if you quote it before going to bed, it will make you open your eyes until dawn! The deeper the baking degree, the less caffeine and tannin. The irritation will also diminish. Don't be fooled by the appearance color of the coffee.

The tannins we don't want to extract are responsible for the astringency of coffee. Tannins are angels and demons, a small amount of tannins can play the sweet and mellow thickness of coffee, a small amount of coffee tannic acid also has a wide range of antibacterial effects! But the finer the grinding and the longer the extraction time, the devil will play a role, making the coffee full of astringency!

In order to prevent excessive extraction of tannins, the key is that coffee beans are ground in roughness, with less powder and slowly extracted at a lower water temperature (below 90 °).

Preventing excessive extraction of tannins is also a great rule for making delicious coffee! Often used to adjust the taste of coffee, so that coffee becomes smooth and delicate, less irritating! (this article is reproduced)