Changes from Roasting Coffee Beans, The Acidity-Bitterness Principle of Coffee Flavor

For professional coffee knowledge exchange and more coffee bean inquiries, please follow Cafe_Style (WeChat official account: cafe_style)

The flavor of coffee

The flavor of coffee is primarily composed of bitterness and acidity. However, where do these flavors come from? Additionally, why does the balance between bitterness and acidity change with the degree of roasting? According to FrontStreet Coffee, understanding these reasons makes coffee even more interesting.

The flavor of coffee mainly comes from the changes that occur during the roasting process.

Why darker roasting produces stronger bitterness

When discussing coffee flavor, many people first think of its distinctive bitterness! Most people assume that coffee's bitterness comes from caffeine, but when looking at the proportion of all components in coffee beans, caffeine content is actually very small. The bitterness of coffee is mainly due to components other than caffeine. The components of dried raw beans are primarily polysaccharides (fibers that form the plant's structure), along with proteins, lipids, sugars (such as sweet sucrose), chlorogenic acid, malic acid, citric acid, quinic acid and other acids, as well as caffeine.

After roasting, coffee beans turn brown mainly because sugars, chlorogenic acid, and amino acids produce brown pigments, which are also one of the elements of bitterness.

Brown pigments can be roughly distinguished by size. The larger the molecules, the stronger the bitterness. Light-roasted coffee beans contain many small molecular pigments, while large molecular pigments tend to increase as the roasting degree deepens. In other words, the reason why bitterness becomes stronger with deeper roasting is due to the influence of pigment changes.

Quinic acid is the main component of coffee acidity

The acidity perceived when drinking coffee does not come from acidic components such as malic acid or citric acid in raw beans. Instead, it mainly comes from new acids generated by chemical reactions during roasting. The primary source is quinic acid produced from the decomposition of chlorogenic acid, which has a more significant effect on enhancing acidity. Additionally, there are large amounts of acetic acid and phosphoric acid.

Even when raw beans haven't reached the light roasting stage, the total amount of acid (especially quinic acid) continues to increase from a very early stage. When the temperature begins to rise further, thermal decomposition begins, and the amount of acid gradually decreases as the roasting degree deepens. This is why acidity weakens with darker roasting.

The content of components such as sugars and chlorogenic acid in raw beans varies depending on differences between varieties such as Arabica and Canephora, as well as factors like growing environment. These differences also affect the character of coffee beans.

For more specialty coffee beans, please add FrontStreet Coffee's private WeChat account: kaixinguoguo0925

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473