
handle: 10533/130251
Abstract A novel ORAC (oxygen radical absorbance capacity) assay to assess antioxidant capacity of phenolic compounds in near-gastric conditions (pH 2.0) is presented. AAPH (2,2′-azo-bis(2-amidinopropane)dihydrochloride) was used as peroxyl radicals source, and fluorescein, pyranine and pyrogallol red were employed as target molecules. Only pyrogallol red (PGR) showed a behavior compatible with an ORAC assay under acidic conditions (ORAC-PGR a ). Excepting Trolox and ascorbic acid, phenolic compounds protected PGR, giving kinetic profiles without the presence of an induction time. ORAC-PGR a values, which reflect the reactivity of the antioxidants toward peroxyl radicals, ranged from 0.2 (caffeic acid) to 29.1 (myricetin) gallic acid equivalents. The ORAC-PGR a method showed analytical parameters in agreement with other ORAC-like assays and was applied to wines, teas, commercial juices and herb infusions, peach juice being the sample with the highest ORAC-PGR a value (7.1 mM gallic acid equivalents). In addition, ascorbic acid concentration in complex mixtures can be determined from kinetic profiles.
570, Food analysis, 540, Pyrogallol red, Phenolic compounds, Antioxidant capacity, Beverages, Acid medium, Food composition, ORAC, Peroxyl radicals
570, Food analysis, 540, Pyrogallol red, Phenolic compounds, Antioxidant capacity, Beverages, Acid medium, Food composition, ORAC, Peroxyl radicals
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