Effect of fermentation technologies on the structural composition of polymeric polyphenols in aged red wines

Abstract

Eight-year-old Syrah red wines were produced using various winemaking technologies. The structural composition of purified polymeric polyphenols (PPpure) from traditional fermentation (Wctrl), prolonged maceration with skins (Wskin), and prolonged maceration with stems (Wstem) was comprehensively analyzed using various depolymerization methods, followed by HPLC-FT-ICR-MS and HPLC/UPLC-QqQ/MS analysis. The results revealed that PPpure consisted of proanthocyanidins, anthocyanins, amino acids, and phenolic acids. Proanthocyanidins were present as both extension and terminal units, with the former being predominant. Amino acids, phenolic acids, and anthocyanins, on the other hand, were exclusively present as terminal units. The proportions of these constituent units in PPpure varied significantly depending on winemaking technologies. When comparing Wskin and Wstem with Wctrl, it was observed that Wskin and Wstem had lower anthocyanins and higher phenolic acids. Furthermore, Wstem exhibited the highest amino acids. Moreover, the mean degree of polymerization (MDP) of the PPpure was influenced by the different fermentation technologies, with MDP values of 25.25, 13.14, and 15.84 for Wctrl, Wskin, and Wstem, respectively. These results indicated that different winemaking technologies significantly affect the structural features of polymeric polyphenols. These findings are crucial in providing practical applications for winemakers to control the polymeric polyphenol composition of wines.