摘要：Antioxidant activity and free radicals were studied in various parts of Vitis vinifera plant in vivo and in wines using EPR spectroscopy. Antioxidative properties of polyphenolic substances play an important role for the evaluation of quality of natural products. Determination of antioxidant activity of experimental samples by EPR method was based on measuring the changes of EPR spectrum of stable nitroxide radicals as a result of their interaction with antioxidants. In the leaves of Vitis vinifera vine varieties for the production of red wines there was observed a higher decrease in free Tempol radicals as compared to the leaves of varieties used for the production of white wines. For all monitored wines there was established a clear decrease in free Tempol radicals to the average value of 75.5 ± 15.6% as compared to the original EPR spectrum. A higher antioxidant activity was observed in yeast sediments from the production of red wines than in those from white ones.
