title: Effects of enzymatic action on the formation of theabrownin during solid state fermentation of Pu-erh tea.
abstract: BACKGROUND
  Theabrownin (TB) is a main bioactive component in Pu-erh tea, and the total amount is between 100 and 140 g kg(-1). However, reports on the mechanism of formation of TB are sparse because it has a high molecular weight and complex composition. Hence, the mechanism of formation of TB in Pu-erh tea during solid state fermentation was investigated using an exogenous enzyme method.
  
  
  RESULTS
  It was found that, in the presence of exogenous enzymes, the tea liquor prepared from the resulting leaves changed considerably in colour. In addition, the TB, total carbohydrate, polysaccharide, amino acid and protein contents were all increased, while the tea polyphenol content decreased sharply; the surfaces of leaves before fermentation appeared to be smooth and intact, and the structures of the cell, cellulose and lignin were complete, while after fermentation their surfaces were covered by microorganisms and the structures of the cells were largely disrupted.
  
  
  CONCLUSIONS
  The enzymatic actions are closely related to the compositional changes occurring during Pu-erh tea manufacture, and its quality. Enzymes produced by microorganisms were found to be the main cause of TB formation during the fermentation of Pu-erh tea.
authors.affiliation: Faculty of Food Science and Technology, Yunnan Agricultural University, Kunming, China.
authors.forename: Qiuping
authors.initials: Q
authors.lastname: Wang
authors.forename: Chunxiu
authors.initials: C
authors.lastname: Peng
authors.forename: Jiashun
authors.initials: J
authors.lastname: Gong
mesh_terms: D044946:Biflavonoids / Q000378:metabolism; D028241:Camellia sinensis / Q000737:chemistry / Q000382:microbiology / Q000648:ultrastructure; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism; D004156:Catechol Oxidase / Q000378:metabolism*; D002480:Cellulase / Q000378:metabolism*; D002681:China; D004032:Diet / Q000208:ethnology; D005285:Fermentation; D005511:Food Handling; D055951:Functional Food / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D010636:Phenols / Q000378:metabolism; D010858:Pigmentation; D018515:Plant Leaves / Q000737:chemistry / Q000382:microbiology / Q000648:ultrastructure; D011096:Polygalacturonase / Q000378:metabolism*; D059808:Polyphenols / Q000378:metabolism; D013499:Surface Properties; D013662:Tea / Q000737:chemistry*
chemical_list: D044946:Biflavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea; C569455:theabrownin; C086701:thearubigin; C056068:theaflavin; D002392:Catechin; D004156:Catechol Oxidase; D011096:Polygalacturonase; D002480:Cellulase