title: Extraction Kinetics of phytochemicals and antioxidant activity during black tea (Camellia sinensis L.) brewing.
abstract: BACKGROUND
  Tea is the most consumed beverage in the world which is second only to water. Tea contains a broad spectrum of active ingredients which are responsible for its health benefits. The composition of constituents extracted to the tea brew depends on the method of preparation for its consumption. The objective of this study was to investigate the extraction kinetics of phenolic compounds, gallic acid, caffeine and catechins and the variation of antioxidant activity with time after tea brew is made.
  
  
  METHODS
  CTC (Crush, Tear, Curl) tea manufactured in Sri Lanka was used in this study. Tea brew was prepared according to the traditional method by adding boiling water to tea leaves. The samples were collected at different time intervals. Total phenolic and flavonoid contents were determined using Folin ciocalteu and aluminium chloride methods respectively. Gallic acid, caffeine, epicatechin, epigallocatechin gallate were quantified by HPLC/UV method. Antioxidant activity was evaluated by DPPH radical scavenging and Ferric Reducing Antioxidant Power (FRAP) assays.
  
  
  RESULTS
  Gallic acid, caffeine and catechins were extracted within a very short period. The maximum extractable polyphenols and flavanoids were achieved at 6-8 min after the tea brew is prepared. Polyphenols, flavanoids and epigallocatechin gallate showed a significant correlation (p < 0.001) with the antioxidant activity of tea.
  
  
  CONCLUSIONS
  The optimum time needed to release tea constituents from CTC tea leaves is 2-8 min after tea is made.
authors.affiliation: Department of Biochemistry & Molecular Biology, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo 08, Sri Lanka. dilankafdo86@gmail.com.|Institute of Chemistry Ceylon, College of Chemical Sciences, Adamantane House, 341/22, Kotte Road, Welikada, Rajagiriya, Sri Lanka. dilankafdo86@gmail.com.
authors.forename: Chamira Dilanka
authors.initials: CD
authors.lastname: Fernando
authors.affiliation: Department of Biochemistry & Molecular Biology, Faculty of Medicine, University of Colombo, Kynsey Road, Colombo 08, Sri Lanka. indunilsree@gmail.com.
authors.forename: Preethi
authors.initials: P
authors.lastname: Soysa
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002110:Caffeine / Q000032:analysis; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005504:Food Analysis; D005707:Gallic Acid / Q000032:analysis; D064209:Phytochemicals / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry; D059808:Polyphenols / Q000032:analysis; D013188:Sri Lanka; D013662:Tea / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000975:Antioxidants; D064209:Phytochemicals; D059808:Polyphenols; D013662:Tea; D002110:Caffeine; D005707:Gallic Acid; D002392:Catechin; C045651:epigallocatechin gallate