Studies On Prodution Theaflavins By Using Enzymes And It’s Characterization

Theaflavins (TFs) is the key influence factor on the quality of black tea. It has many powerful pharmacological effects. There are extensive application prospects in the fields of functional foods and drink, natural medicine, daily chemical industry, etc. In order to solve the problems such as the lower contents of theaflavins in black tea and the lower yield of extraction from black tea, this based on the enzyme resources of the formation of theaflavins. The theaflavins was synthesized from tea polyphenol by using pear PPO and laccase enzyme-catalysing oxidation. This research also involved the study of vitro antioxidant activity and the stability of theaflavins.(1)The determination of the activity of the PPO from different enzyme resources (pear, apple, potato, banana, mushroom, fresh tea), the Suberase PPO and Denilite IIS laccase enzyme showed that the activity of them:pear PPO>Denilite IIS laccase enzyme>Suberase PPO>banana PPO>apple PPO>potato PPO>mushroom PPO>tea PPO.Enzymatic kinetic curve showed the PPO form different resources have very great differences. Pear PPO and Denilite IIS Laccase Enzyme have more advantages than other PPO to formatting theaflavins. In their reaction systems, the residual contents of catechins are far less. So Pear PPO and Denilite IIS Laccase Enzyme are reliable to product theaflavins.The study of the effect of the PPO activity and the formation of theaflavins from the metal ions showed that0.1mmol/L Cu2+could improved the PPO activity and the formation of theaflavins.(2)The theaflavins was synthesized from tea polyphenol by using pear PPO and laccase enzyme-catalysing oxidation. The results showed that the pH value of the present system is3.5, the optimum condition of theaflavins synthesizing by using pear PPO is30"Ctemperature, the addition of enzymes is10ml (the activity of the enzyme493.00u/min.mL), oxygen time is1.5h; the optimum condition of theaflavins synthesizing by using Denilite IIS Laccase Enzyme is50癈temperature, the addition of enzymes is1.5mg/ml (the activity of the enzyme194.13u/min.mg), oxygen time is1.5h. By using this method, the yield of theaflavins is more than the method by using single enzyme.(3)Theaflavins in vitro antioxidant activity of the study results showed that:in the DPPH scavenging ability of theaflavins, O2". scavenging ability,.OH scavenging capacity, reducing power and antioxidant activity to inhibit lipid body was stronger than tea polyphenols and positive reference substance.(4)The results show that the stability of theaflavins:high temperature and alkali will make a significant reduction in levels of theaflavins, theaflavin content of light on little effect on.