Polyphenol Composition of Skin-Contact Fermented ‘Solaris’ and ‘Zilga’ Wines

Abstract

The objective of the study was to determine the effect of vintage and cultivar on the total polyphenol content and the antioxidant activity of wines made from the white wine cultivar ‘Solaris’ and the red wine cultivar ‘Zilga’ (both with skin maceration). The second goal was to describe the polyphenolic profile of ‘Solaris’ wine and compare it with that of ‘Zilga’ wine. Spectrophotometric methods were employed to determine the total polyphenol content and the antioxidant activity. High-performance liquid chromatography (HPLC) was used to determine the polyphenol composition. The total polyphenol content and the antioxidant activity of ‘Solaris’ wine differed significantly from that of ‘Zilga’ wine in the experimental years from 2021 to 2023. Significant differences between the wines also occurred on average over the years, with a significantly higher total polyphenol content and antioxidant activity obtained for the red wine of ‘Zilga’. However, both wines were similarly influenced by vintage over the three-year experimental period. The antioxidant activity showed a high correlation with the total polyphenol content. The polyphenolic profile of ‘Solaris’ wine differed notably from that of ‘Zilga’ wine. While ‘Solaris’ wine exhibited lower levels of phenolic acids and flavonols, the content of the flavanols was significantly higher, even double that of ‘Zilga’ wine. Among the flavanols, there was a remarkably high content of catechin and epicatechin.