Effect of different additives on the theabrownin and its formation mechanism during Pu-erh tea fermentation.

Sun-dried green tea prepared from the fresh leaves of Camellia sinensis var. assamica was used as its starting materials by solid state fermentation. Results showed that the appearance color and soup color value of fermented tea leaves with different treatments showed significant difference. The content of theabrownin in fermented tea leaves in addition of glucose, gallic acid, pyrogallol, pyrocatechol, glycine and mixtures of glucose and gallic acid is 6.99%, 11.29%, 10.22%, 6.31%, 9.25% and 7.30% respectively, and their content is higher than that in dried tea sample (control 1, 1.76%) and fermented sample (2.78%) only added with distilled water (control 2). It is found that there is no significant difference between the samples treated with glucose, gallic acid, pyrogallol, pyrocatechol and glycine as well as administering with potassium sorbate and the control. The results also showed that the ascorbic acid reaction and the components within tea leaves also enhance theabrownin production.