The bitterness of coffee. How did coffee bitterness come from?

Caffeine is the most well-known bitter ingredient in coffee, but caffeine actually accounts for only 10% of the bitter taste. This can be understood from the fact that the concentration of caffeine in roasted beans is not affected by the degree of baking, and that decaffeinated coffee also has a bitter taste.

So where does the remaining 90% of the bitterness come from?

One of the sources of coffee bitterness is brown pigment.

Brown pigments can be classified according to molecular size, and the larger the molecule, the stronger the bitterness. In the case of coffee, deep roasting increases the brown pigment, and so does the pigment with larger molecules (the more bitter). When you boil deeply baked beans in daily life, you will find that the bitter taste is stronger and the taste is more rich.

In fact, the bitterness intensity and taste of Arabica and Robusta are not the same. This is also due to the difference between the amount and molecular size of brown pigment. Robusta species have lower oligosaccharide content than Arabica species, do not caramelize, and are easy to produce larger molecular pigments, so even light baking tends to taste rich bitterness.

Another source of bitterness is the seven diamino acid cyclized derivatives produced when amino acids and proteins are heated. This is a material formed by the combination of two amino acids, and the intensity of bitterness varies with different ways of binding. In addition to coffee, part of the bitterness of cocoa, black beer and so on is also made up of this substance.

So, is the intensity and intensity of bitterness uncontrollable? Yes, of course. The bitterness can be changed as long as the type, baking degree, baking method and extraction method of coffee beans are changed.