What's wrong with my caffeic acid? why does coffee turn sour? what is good coffee?

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Coffee contains all kinds of acids, most of which can be found in agricultural products:

Amino acids such as asparagic acid, glutamic acid and leucine; when the concentration of amino acid exceeds the normal value, it will produce sweetness.

Carbolic acids such as caffeic acid, chlorogenic acid and quinic acid; when the concentration of carbolic acid exceeds the normal value, it will produce bitterness.

Fatty acids such as acetic acid, lactic acid, citric acid, fumaric acid, oxalic acid, phosphoric acid and tartaric acid; when the concentration of fatty acid exceeds the normal value, it will produce sour taste.

Fatty acids make coffee taste bright and fragrant, which is why high-priced coffee has high acidity (low PH 4.8-5.1).

. the strength of acids in coffee are tartaric acid, citric acid, malic acid, lactic acid and acetic acid.

. the strength of the acid affects other flavors of coffee, especially sweetness.

. each acid has its own unique taste, such as lemon flavor of citric acid, cream flavor of lactic acid, apple flavor of malic acid, etc.

. the aroma caused by acid is easier to feel through the sense of smell than the sense of taste.

* Acid > base value order: lemon > beer > Arabica coffee beans > Robska coffee beans > milk > water

It doesn't hurt to drink more coffee, but it's okay to drink more water!