Title: Methodology for the measurement of antioxidant capacity of coffee : a validated platform composed of three complementary antioxidant assays
Authors : Opitz, Sebastian
Smrke, Samo
Goodman, Bernard A.
Yeretzian, Chahan
Published in : Processing and Impact on Antioxidants in Beverage
Pages : 253
Pages to: 264
Editors of the parent work: Preedy, Victor R.
Publisher / Ed. Institution : Academic Press
Publisher / Ed. Institution: London
Issue Date: 2014
License (according to publishing contract) : Licence according to publishing contract
Type of review: Not specified
Language : English
Subjects : Antioxidants; Coffee; Health
Subject (DDC) : 663: Beverage technology
Abstract: A platform composed of three complementary and validated antioxidant assays is proposed for the routine and fast assessment of the antioxidant capacity of coffee brews. Firstly, a brief review of the principles underlying antioxidant measurements in foods, and the rationale behind the development of an analytical platform for measuring the antioxidant capacity of coffee is given. A range of complementary methods is described based on either hydrogen atom or electron transfer reactions. Secondly, three total antioxidant capacity (TAC) assays are recommended for the platform. Two are based on electron-transfer reactions—the Folin–Ciocalteu (FC) assay for total phenols, and the ABTS assay, which on oxidation forms the cationic chromophore, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) (ABTS•+). The third, which is based on hydrogen-atom transfer, is the oxygen radical absorbance capacity (ORAC), in which the antioxidant and the substrate fluorescein compete for thermally generated peroxyl radicals after their formation by decomposition of 2,​2′-​azobis-​2-​amidinopropane,​dihydrochloride (AAPH). Finally, validated protocols for conducting these three assays, using flow injection analysis (FIA), are presented along with actual results to illustrate their reproducibility and robustness. The three assays are combined into an analytical platform to profile and compare the antioxidant potential of a series of roasted coffee samples. Antioxidant values obtained with the same dark-roast coffee are 2103, 710, and 5868 gallic acid equivalents (GAE) for the FC, ABTS, and ORAC assays, respectively. These numbers thus reflect the different types of chemical reaction that are performed, and illustrate the fact that assays for TAC are actually selective (and hence complementary) for specific types of antioxidant molecule.
Departement: Life Sciences und Facility Management
Organisational Unit: Institute of Chemistry and Biotechnology (ICBT)
Publication type: Book Part
DOI : 10.1016/B978-0-12-404738-9.00026-X
ISBN: 978-0-12-404738-9
URI: https://digitalcollection.zhaw.ch/handle/11475/5472
Appears in Collections:Publikationen Life Sciences und Facility Management

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