Changes of Active Constituents and Antioxidant Properties of Four Kinds of Tea during Gastrointestinal Digestion in Vitro

In order to recognize the changes of active ingredients in tea in vivo,the four kinds of tea of Zijuan,Zhonghuang Yihao,Baiye Yihao and Fuding Dabai were selected. The changes of polyphenols,flavonoids,proanthocyanidins and antioxidant activity were determined through simulated gastrointestinal digestion in vitro. The results showed that the content of polyphenols and total flavonoids in Fuding Dabai tea was the highest,while the content of proanthocyanidins in Zijuan tea was the highest. DPPH free radical scavenging ability of Fuding Dabai tea was the highest,while the Zijuan ABTS free radical scavenging ability was the best. Compared the gastric digestion stage(0~2 h)with the intestinal digestion stage(2~4 h),it was found that the polyphenol content of the four kinds of tea decreased significantly during the gastric digestion stage,and the proanthocyanidins content did not decrease significantly. The content of flavonoids in Fuding Dabai,Zhonghuang Yihao and Baiye Yihao kinds of tea showed a downtrend,while Zijuan tea increased. In the intestinal digestion stage,the content of polyphenols and flavonoids in Fuding Dabai,Zijuan,Zhonghuang Yihao and Baiye Yihao increased,while the proanthocyanidin content decreased. The scavenging ability of DPPH free radical and ABTS free radical of the four kinds of tea in simulated gastrointestinal digestion decreased gradually.