title: Catechin concentrates of garden tea leaves (Camellia sinensis L.): extraction/isolation and evaluation of chemical composition.
abstract: BACKGROUND
  Solid-liquid (SLE) and liquid-liquid (LLE) extraction techniques were applied to extract catechins and caffeine from quick mechanically expelled tea leaf juice (QMETLJ) and freeze-dried (FD)-QMETLJ of Camellia sinensis L. The concentrates obtained were analyzed for total polyphenol content and antioxidant activity (DPPH(•) inhibition, FRAP and phosphomolybdenum assay). Catechins were identified and quantified using HPLC.
  
  
  RESULTS
  Overall, 95% (v/v) ethanol was the best solvent system for extracting total polyphenols (355.26 ± 23.68 to 457.89 ± 28.94 g GAE kg(-1) extractable solid yield (ESY)) and antioxidants (DPPH(•) inhibition, 16.97 ± 0.52 to 20.83 ± 3.11%; FRAP, 4.15 ± 0.32 to 6.38 ± 0.57 mmol TE g(-1) ESY; Mo(V) reduction, 2.47 ± 0.19 to 3.84 ± 0.39 mmol AAE g(-1) ESY) from FD-QMETLJ. Similarly, in LLE, ethyl acetate showed the best results for recovering polyphenols (960.52 ± 7.89 g GAE kg(-1) ESY) and antioxidants (DPPH(•) inhibition, 42.39 ± 0.91%; FRAP, 11.39 ± 0.83 mmol TE g(-1) ESY; Mo(V) reduction, 6.71 ± 1.14 mmol AAE g(-1) ESY) from QMETLJ.
  
  
  CONCLUSIONS
  It was found that 95% ethanol can be used to increase the total polyphenols and antioxidants in extracts from FD-QMETLJ, while ethyl acetate can be effectively employed for concentrating catechins from QMETLJ.
authors.affiliation: Department of Food Engineering, CSIR (Council of Scientific and Industrial Research, India), Central Food Technological Research Institute, Mysore, 570 020, India; Academy of Scientific and Innovative Research, New Delhi, 110 001, India.
authors.forename: Pravin Vasantrao
authors.initials: PV
authors.lastname: Gadkari
authors.forename: Udaya Sankar
authors.initials: US
authors.lastname: Kadimi
authors.forename: Manohar
authors.initials: M
authors.lastname: Balaraman
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry*; D059625:Liquid-Liquid Extraction; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry*; D059808:Polyphenols / Q000737:chemistry; D052616:Solid Phase Extraction
chemical_list: D010936:Plant Extracts; D059808:Polyphenols; D002392:Catechin
keywords: Camellia sinensis L; antioxidant activity; catechins; liquid-liquid extraction; solid-liquid extraction