title: A comparison of antioxidative capacities of fruit juices, drinks and nectars, as determined by EPR and UV-vis spectroscopies.
abstract: The differences in the Trolox Equivalent Antioxidant Capacity (TEAC) values at the same incubation time obtained by two different techniques: electron paramagnetic resonance (EPR) spectroscopy and ultraviolet visible (UV-vis) spectroscopy, which use the same antioxidant-free radical reaction mechanism, were determined for fruit juices, nectars and drinks. For this study, the stable free radical 1,1-Diphenyl-2-picryl-hydrazyl (DPPH(•)) was used. The antioxidant capacity was presented in Trolox Equivalents, e.g., μM trolox per 100 ml of sample. All of the studied fruit juices, drinks and nectars showed antioxidative properties. Dependencies between TEAC values and the percent fruit content and sample color were observed for the studied beverages. It was found that EPR spectroscopy is the more adequate method for determining TEAC values for these kinds of samples.
authors.affiliation: Department of Materials Chemistry and Chemical Technology, Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice, Poland. Electronic address: mariola.bartoszek@us.edu.pl.
authors.forename: Mariola
authors.initials: M
authors.lastname: Bartoszek
authors.affiliation: Department of Materials Chemistry and Chemical Technology, Institute of Chemistry, University of Silesia, 9 Szkolna Street, 40-006 Katowice, Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Polak
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005638:Fruit / Q000737:chemistry*; D000067030:Fruit and Vegetable Juices / Q000032:analysis*; D057048:Plant Nectar / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D000975:Antioxidants; D057048:Plant Nectar
keywords: Antioxidant capacity; Drinks; EPR spectroscopy; Fruit juices; Nectars; UV–vis spectroscopy