title: Coulometric titration with electrogenerated oxidants as a tool for evaluation of cognac and brandy antioxidant properties.
abstract: Stoichiometric coefficients for reactions of cognac antioxidants with coulometric titrants (electrogenerated bromine and hexacyanoferrate(III) ions) have been found. Ellagic and gallic acids react with both titrants while aldehydes (vanillin, syringic and coniferaldehyde) - with electrogenerated bromine only. Furfurals do not show significant reactivity toward both oxidants. Cognac and brandy total antioxidant capacity (TAC) and ferric reducing power (FRP) based on reactions with electrogenerated bromine and hexacyanoferrate(III) ions, respectively, have been evaluated. Both parameters for cognacs are statistically significant higher than for brandies and grow with the age increase. Beverages under investigation has shown relatively high antiradical activity toward 2,2-diphenyl-1-picrylhydrazyl (7-92% and 5-93% for cognacs and brandies, respectively). Total phenolics content has been evaluated by Folin-Ciocalteu method. Older beverages represent the higher phenolics content caused by more time of extraction from oak barrels. Positive correlations (r=0.8077-0.9617) have been observed for TAC and FRP with antiradical activity and total phenolics content.
authors.affiliation: Analytical Chemistry Department, Kazan Federal University, Kremlyevskaya, 18, Kazan 420008, Russian Federation. Electronic address: Ziyatdinovag@mail.ru.
authors.forename: Guzel
authors.initials: G
authors.lastname: Ziyatdinova
authors.affiliation: Analytical Chemistry Department, Kazan Federal University, Kremlyevskaya, 18, Kazan 420008, Russian Federation.
authors.forename: Inna
authors.initials: I
authors.lastname: Salikhova
authors.affiliation: Analytical Chemistry Department, Kazan Federal University, Kremlyevskaya, 18, Kazan 420008, Russian Federation.
authors.forename: Herman
authors.initials: H
authors.lastname: Budnikov
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D017186:Titrimetry / Q000295:instrumentation / Q000379:methods*; D014920:Wine / Q000032:analysis*
chemical_list: D000975:Antioxidants; D016877:Oxidants; D010636:Phenols
keywords: Antioxidant properties; Cognac; Constant-current coulometry; Electrogenerated oxidants; Ferric reducing power; Food analysis; Total antioxidant capacity; Total phenolics