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Separation of catechins from green tea (Camellia sinensis L.) by microwave assisted acetylation, evaluation of antioxidant potential of individual components and spectroscopic analysis.

Selvi, I. K. and Nagarajan, S. (2018) Separation of catechins from green tea (Camellia sinensis L.) by microwave assisted acetylation, evaluation of antioxidant potential of individual components and spectroscopic analysis. LWT - Food Science and Technology, 91. pp. 391-397. ISSN 0023-6438

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Abstract

Separation of individual green tea catechins has the limitation due to their structural resemblance and unequal distribution. Hence, the objective of this study was to develop separation methods based on 1.Preparative Thin Layer Chromatography (TLC) using oxalic acid impregnation and 2. Microwave (MW) mediated acetylation followed by classical silica gel column chromatography separation. The yield of total catechins by different extraction techniques was, conventional (7.3%), liquid-liquid (7.8%), Soxhlet (8.3%) and microwave (8.8%). Acetylation of total catechins under various MW conditions explored with acetic anhydride, triethylamine and standardized at 15 min at 1g scale and subjected to separation. Subsequently, the individual catechin acetates deacetylated under MW conditions and characterized by TLC, High-Resolution Mass Spectrometry (HRMS), Fourier Transform Infrared Spectroscopy (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic studies. The total polyphenol content of the extract was 931.17 ± 0.67 g GAE kg−1. The antioxidant activity of deacetylated catechins was evaluated by Ferric-Reducing Antioxidant Potential (FRAP) in terms of Trolox equivalence (TE) and % inhibition of 1, 1-diphenyl-2-picryl-hydrazyl (DPPH). Accordingly, the TE and DPPH % inhibition was epigallocatechingallate (12.3 and 71.9%), epicatechingallate (11.5 and 55.5%), epigallocatechin (9.10 and 46.0%), epicatechin (7.40 and 35.1%) respectively.

Item Type: Article
Uncontrolled Keywords: Green tea catechins Chromatography Microwave acetylation Antioxidant activity
Subjects: 600 Technology > 07 Beverage Technology > 08 Tea
600 Technology > 08 Food technology > 32 Antioxidants
Divisions: Plantation Products Spices and Flavour Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 04 Jul 2018 10:59
Last Modified: 04 Jul 2018 10:59
URI: http://ir.cftri.com/id/eprint/13583

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