The origin and formation of the sour taste of roasted coffee

Raw coffee beans contain sour ingredients such as citric acid, malic acid, quinic acid and phosphoric acid, but these are not the main sources of sour taste when drinking coffee. The acid produced during baking is the main source of sour taste.

Raw beans produce a series of chemical reactions during baking to form new acids. The most important thing is that chlorogenic acid is decomposed into quinic acid, and oligosaccharides are decomposed into formic acid and acetic acid. During the baking process, the sour substances will continue to increase, but as the baking continues, the high temperature will cause these substances to decompose, after a certain stage, continue baking will only reduce the sour taste.

The most acid in roasted coffee beans is quinic acid produced during baking. There are also a lot of other citric acid, acetic acid, phosphoric acid and so on. The strength and concentration of each acid is different, so there is a complicated problem behind the sour taste of coffee.

The sour ingredients and specific gravity of coffee beans are also related to the ingredients contained in raw coffee beans, and what type of coffee beans you choose will also affect the production of sour taste to a certain extent. The content of oligosaccharides in Congo is relatively low, and oligosaccharides are the source of acetic acid, so it can not produce a volatile and refreshing sour taste after baking.

The appearance of sour taste will also be changed by the state of quinic acid. Quinic acid contains ingredients that show sour taste and inhibit sour taste. Brewed coffee will slowly become sour with the decrease of temperature. It is precisely because the ingredients that inhibit sour taste are losing their effectiveness, thus showing more sour taste.