Comparison of Identification and Determination of Phenolic Compounds and Antioxidant Potential of Selected Red Wines

The quantitative composition of phenolic compounds and the antioxidant activity of Serbian and Bulgarian red wines from various vintages were analyzed and compared in this study. Phenolic profiling was conducted using high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD), revealing a total of 29 identified phenolic compounds, including 16 anthocyanins, 7 flavonols, and 6 hydroxycinnamic acids and their derivatives. The antioxidant potential of the red wines was assessed using four distinct analytical methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, ferric-reducing/antioxidant power (FRAP), cupric-ion-reducing capacity in the presence of neocuproine (CUPRAC), and total reducing power (TPR). The correlation of the examined results was monitored, and the results showed that the antioxidant qualities of wines are most strongly correlated with the total content of phenols and flavonoids, while the correlations are weakest for their total anthocyanins. Compositions of phenolics varied from 1016 mg/L to 4115 mg/L, while the value of flavanols was in a wide range from 438 mg/L to 2890 mg/L, whereby the average proportion of flavonoids to total phenols was 52.4%. The wine named Ruen 2019 showed the presence of the highest amount of total phenolics and total flavonoids present, followed by Prokupac and Evita cultivars. Of the tested monoglucoside anthocyanins in all wines, malvidin-3-O-glucoside was the most abundant.