Reexamination of the ORAC assay: Effect of metal ions

Nkhili Ezzorha, Brat Pierre. 2011. Reexamination of the ORAC assay: Effect of metal ions. Analytical and Bioanalytical Chemistry, 400 (5) : 1451-1458.

Quartile : Q1, Sujet : CHEMISTRY, ANALYTICAL / Quartile : Q1, Sujet : BIOCHEMICAL RESEARCH METHODS

Résumé : The oxygen radical absorbance capacity (ORAC) assay method has been employed extensively in the field of antioxidant and oxidative stress. It uses fluorescein as probe for oxidation by peroxyl radical. Hundreds of reports have been published on the use of this method to determine antioxidant capacity in food and biological samples. The question is whether the results of all these reports are influenced by antioxidant autoxidation, which occurs during the ORAC test. Indeed, the presence of metal ions in the studied matrix will influence antioxidant stability, thereby leading to the underestimation of their antioxidant properties. Ethylenediaminetetraacetic acid hydrate (EDTA) can be used as a metal complexation agent. This paper examines the effect of the addition of EDTA on the ORAC values of pure compounds (quercetin, ascorbic, and dehydroascorbic acid) and five food juices (kiwi, orange, tomato, red grape, and apple). Metal complexation by EDTA (80 ?M) clearly increased the ORAC values, given that the antioxidant was protected against rapid autoxidation incited by trace metal ions within samples and then by free radicals. Our finding also undoubtedly demonstrated that the number of literature values is potentially underestimated.

Mots-clés Agrovoc : jus de fruits, composé phénolique, antioxydant, élément métallique

Classification Agris : Q04 - Composition des produits alimentaires
U30 - Méthodes de recherche

Champ stratégique Cirad : Axe 3 (2005-2013) - Alimentation accessible et de qualité

Auteurs et affiliations

• Nkhili Ezzorha, CIRAD-PERSYST-UMR Qualisud (FRA)
• Brat Pierre, CIRAD-PERSYST-UMR Qualisud (FRA) ORCID: 0000-0003-0429-9575

Source : Cirad - Agritrop (https://agritrop.cirad.fr/559696/)

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