Difference Analysis of Bioactive Components of Yunnan Large-leaf Tea by Different Processing Technologies

To investigate the differences in the composition and content of bioactive components within Yunnan large-leaf tea (green tea, Pu-erh raw tea, black tea, Pu-erh ripe tea), key characteristic components were mined. In this study, 57 green teas, 52 raw Pu-erh teas, 23 black teas, and 18 ripe Pu-erh teas were used as test samples to analyze the active components and physicochemical indexes in tea, such as gallic acid, catechin, epicatechin, kaempferol, myricetin, quercetin, caffeine, theophylline, theaflavin, thearubigin, theabrownin, water extract, and water. Correlation analysis (CA), principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) were used to statistically analyze the content of active ingredients. The results showed that green tea had the highest average contents of water extract and kaempferol, with contents of 47.89% and 1.596 mg/g respectively. The average contents of catechin, epicatechin, quercetin and myricetin in Pu'er raw tea were the highest, which were 0.555%, 1.332%, 2.628 mg/g and 0.46 mg/g, respectively. The average contents of theaflavin, thearubigin and caffeine in black tea were the highest, which were 0.25%, 6.75% and 3.278%, respectively. The average contents of theabrownin, gallic acid, water and theophylline were the highest in ripe Pu'er tea, which were 15.294%, 0.433%, 9.34% and 25.583 mg/kg, respectively. The contents of water extract, catechin, epicatechin, myricetin and quercetin were higher in unfermented tea, while the contents of gallic acid and theabrownin were higher in fermented tea, indicating that the processing technology had a influence on the active ingredients. Correlation analysis showed that different processing technology led to different correlation between active components, but there was a extremely significant positive correlation between catechin and epicatechin in all four kinds tea. PCA and OPLS-DA further identified theaflavins and thearubin were the key characteristic components of black tea, theabrownin and gallic acid were the key characteristic components of Pu-erh ripe tea, catechins, epicatechin, myricetin, quercetin could be used as the characteristic components of green tea and Pu'erh raw tea. This study provides scientific basis for the utilization of tea functional components and the development of new products.