Now I love drinking tea very much, but when I was little, I didn't like it because it is a bitter drink. Children naturally prefer sweet foods and dislike bitter tastes. After trying it out of curiosity back then, I kept my distance. So the question arises, why do we find tea so bitter?

We find tea bitter because tea leaves contain substances that impart a bitter taste. The main bitter substances in tea leaves are caffeine, theobromine, theophylline, anthocyanins, tea saponins, bitter amino acids, and some flavanols. If we find a tea very bitter, it indicates that alkaloids dominate the composition of the tea infusion.

Alkaloids refer to a class of nitrogen-containing organic compounds derived from living organisms. They have alkali-like properties and can combine with acids to form salts. Most are optically active and have a specific and significant physiological effect on the central nervous system of animals.

For example, I once discovered that the sun-dried green tea from Pare Village in Mengsong Township had an exceptionally bitter taste. Experimental research revealed that it contained particularly high levels of a bitter alkaloid. This bitter alkaloid is one type of alkaloid. Of course, this is a special case; most teas do not contain this specific bitter alkaloid.

Generally, the alkaloids in tea leaves are highest in caffeine content, usually 2%-4%. Caffeine has a bitter taste and a low threshold. Research by Chen Zongdao et al. (1992) showed that temperature and pH affect sensitivity to bitterness. As pH and temperature increase, the threshold decreases, and sensitivity increases. The caffeine content varies significantly in different parts of the tea plant, being highest in the leaves, lower in the stems, and decreasing in new shoots as the leaves age.

The overall sensation presented by the tea infusion refers to the synergistic and restrictive interactions among the internal substances in the tea soup. When we drink tea and find it bitter, it means that bitter substances are dominant in the tea infusion. Generally, this can simply be understood as caffeine overpowering the presentation of substances like catechins.