| Literature DB >> 26593628 |
Abstract
The effect of oxygen on the two separate one-electron reactions involved in the oxidation of ascorbic acid was investigated. The rate of ascorbate radical (Asc(-)) formation (and stability) was strongly dependent on the presence of oxygen. A product of ascorbic acid oxidation was measurable levels of hydrogen peroxide, as high as 32.5 μM from 100 μM ascorbic acid. Evidence for a feedback mechanism where hydrogen peroxide generated during the oxidation of ascorbic acid accelerates further oxidation of ascorbic acid is also presented. The second one-electron oxidation reaction of ascorbic acid leading to the disappearance of Asc(-) was also strongly inhibited in samples flushed with argon. In the range of 0.05-1.2 mM ascorbic acid, maximum levels of measurable hydrogen peroxide were achieved with an initial concentration of 0.2 mM ascorbic acid. Hydrogen peroxide generation was greatly diminished at ascorbic acid levels of 0.8 mM or above.Entities:
Keywords: Ascorbate radical; Ascorbic acid; Ascorbyl radical; Dehydroascorbate; Hydrogen peroxide
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Year: 2015 PMID： 26593628 DOI： 10.1016/j.foodchem.2015.07.141
Source DB: PubMed Journal: Food Chem ISSN： 0308-8146 Impact factor: 7.514