The study of antioxidant capacity of varieties of nalewka, a traditional Polish fruit liqueur, using EPR, NMR and UV-vis spectroscopy

The antioxidant properties of various kinds of the traditional Polish alcoholic beverage nalewka were investigated using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-vis) spectroscopy. The antioxidant capacity was measured by EPR spectroscopy in μmol Trolox (TE) in a 100 mL nalewka sample. The total phenolic content was measured by Folin-Ciocalteu (FC) assays while aromatic proton content (Har) was determined by NMR spectroscopy; subsequently the correlation among these values was explored. All of the investigated nalewkas exhibited antioxidant properties. The values of Trolox equivalent antioxidant capacity (TEACDPPH) were in the range 45-1045 μmol TE/100 mL. It was found that the value of the TEACDPPH corresponded to the TP (r = 0.96) and Har (r = 0.95). Moreover, the TEACDPPH values depended on the kinds of fruits used for nalewkas' preparation.