6533b86dfe1ef96bd12c94c4
RESEARCH PRODUCT
Ascorbic Acid Oxidation in Sucrose Aqueous Model Systems at Subzero Temperatures
Martine Le MesteEleni KalogianniPhilippe CayotD. SimatosDominique Championsubject
SucroseSucroseReactionDiffusionAnalytical chemistryAscorbic Acid010402 general chemistry01 natural scienceslaw.inventionCyclic N-OxidesReaction rate[SPI]Engineering Sciences [physics]chemistry.chemical_compoundViscosityReaction rate constantlawFreezing0103 physical sciencesVitamin CElectron paramagnetic resonanceAqueous solution010304 chemical physicsdiffusionElectron Spin Resonance SpectroscopyTemperatureWaterTempolNegative temperaturesGeneral ChemistryAscorbic acid0104 chemical sciencesSolutionsKineticschemistryBiochemistrySpin LabelsElectron paramagnetic resonanceGeneral Agricultural and Biological SciencesOxidation-ReductionCryoconcentrationdescription
The reduction of Tempol by ascorbic acid in concentrated sucrose solutions was measured by electron paramagnetic resonance (EPR) at temperatures ranging from 16 to −16 °C. This method allowed the determination of the rate constants (k) of this fast reaction, by recording the Tempol reduction as a function of time. The two reactants were initially separated and had to migrate for the reaction to occur. The experimental findings were compared with predicted values according to the equation for diffusion-controlled reaction proposed by Atkins. The experimental reaction rate constants were observed to be lower than the calculated ones. However, the experimental values were found to be controlled by the temperature and viscosity changes of the reaction media, as expected for a diffusion-controlled reaction. Keywords: Vitamin C; Tempol; electron paramagnetic resonance; negative temperatures; reaction; cryoconcentration; diffusion
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2004-06-01 | Journal of Agricultural and Food Chemistry |