Quality Component Analysis and Antioxidant Function of Theabrownins from Liupao Tea during Fermentation Process

This study investigated the changes of the sensory qualities of appearance, color, aroma, taste, leaf bottom and the chemical components of tea polyphenols, free amino acids, soluble sugar, caffeine, flavonoids, theabrownin (TB), theaflavin (TF) and thearubigin (TR) using the Liupao tea during processing and was produced by group species Zhongcha Tea Factory in Cangwu County, Wuzhou City, Guangxi, China. In addition, the chemical composition, and the antioxidant of the theabrownin (TB) that extracted from the Liupao tea were investigated. The results showed that the contents of water extract, tea polyphenols, thearubigin (TR), free amino acids and flavonoids were significantly decreased during the fermentation process (P<0.05), while the content of TB was significantly increased (P<0.05). The taste of tea had changed from strong and irritant to mellow and smooth. With the increasing of fermentation days, the contents of total sugar, total protein and total phenol in theabrownins all showed an increasing trend. In vitro antioxidant assays showed that the half maximal inhibitory concentration (IC₅₀) of each group were 10.09 μg/mL (V_C), 69.33 μg/mL (20 d), 49.95 μg/mL (40 d) and 51.85 μg/mL (60 d). The scavenging activity of DPPH free radical was as follows: V_C>40 d>60 d>20 d. The results of this study would provide a theoretical basis for the production and processing of Liupao tea.