Catechin

Catechin is produced from tea leaves through processes such as alcohol extraction, concentration, separation, extraction, enzymatic hydrolysis, concentration, and drying.
Its main components are catechins, including epicatechin (EC), epigallocatechin (EGC), hydrated epicatechin gallate (ECG·H₂O), hydrated epigallocatechin gallate (EGCG·H₂O), gallocatechin gallate (GCG), and catechin (dl-C). The total catechin content (on a dry basis) is ≥90 g/100g, with EGCG content ≥50 g/100g.
Studies have shown that catechins in green tea can inhibit the growth and reproduction of most pathogenic bacterial strains, with ECG and EGCG exhibiting the strongest effects. Research has found that catechins have inhibitory effects on both bacteria and fungi, though the effectiveness varies. The antibacterial effect is stronger than the antifungal and antimold effects. Zeng Liang et al. studied the antibacterial efficacy, stability, and mechanism of catechins. Through the inhibition zone test, they found that catechins have a higher inhibitory rate against Gram-positive bacteria than against Gram-negative bacteria, with a more pronounced effect. Thermal stability tests revealed that catechins exhibit the best antibacterial effect at temperatures between 25–80°C, unaffected by temperature conditions. pH stability experiments indicated that catechins are more stable under acidic conditions than under alkaline conditions.

In addition, catechin compounds also have effects such as inhibiting obesity, preventing cardiovascular diseases and diabetes, regulating gut microbiota, and preventing dental diseases. Research on catechins is the most prominent among the four major components of tea polyphenols. Undoubtedly, the various important functions of catechins that have been confirmed are a major reason why they have become a research hotspot.