4. Quality control and social impact

4.1 Quality control

The chemical composition of tea leaves has been extensively studied. Leaf constituents, as presented in the section on tea biochemistry, are divided for quality into 8 basic groups: A (polyphenols), B (methylxanthines, caffeine/theine and related compounds), C (proteins and amino acids), D (carbohydrates, pectins and fibers), E (organic acids and vitamin C), F (lipids, chlorophylls, carotenoids and related compounds), G (vitamins and minerals), H (aroma). Some of these compounds can therefore be used as quality markers. For example, grade can be checked, as the closer the tea leaf is to the bud, the richer it is in these components, and the faster and more intensely the infusion takes place.

It has also been shown that there is a correlation...