Phenolic composition and antioxidant activity of seeds and stems of hybrid grapes

Abstract

Winemaking in France dates more than 400 BCE and it has evolved a lot through the ages. Today, it faces two major problems: the over usage of pesticides and rapid progress of climate change. One of the strategies to overcome these issues is the employment of hybrid varieties. Such varieties can however present an unusual characteristic phenolic profile. In red grapes, phenolics are the main components responsible for the flavor profile and they also are associated with health benefits, however their concentration and exact composition varies depending on the year and compartment of the grape that is considered. The main aim of this research was to broaden the knowledge on the phenolic composition of hybrid grapes by gathering the phenolic profile of seeds and stems of four new hybrid grapes: Vidoc, Artaban, Coliris and Chamburcin, over three vintages (2022-2024). Phenolic compounds were extracted from seeds and stems using solid/liquid extraction. The obtained phenolic extracts underwent chemical analysis including Total Phenol Concentration (TPC), Total Tannin Concentration (TTC), Total Anthocyanin Concentration (TAC). To determine the phenolic profile of the extracts, two methods for UPLC – DAD were used, one for phenols present in red wine and one specifically targeting anthocyanins. Antioxidant activity was also assessed through DPPH assay. Notable differences were observed both among the different hybrids, as well as between seeds and stems within the same hybrid variety over the different vintages taken into consideration. Vintage variation seems to affect stems more than seeds, which may indicate the higher sensibility of stems to climate parameters. Regarding UPLC-DAD results, 16 compounds were identified and quantified in grape stems, while only 9 compounds were successfully identified and quantified in seeds. Nevertheless, some of the compounds identified in seeds were present in only one of the varieties studied, showing their potential to be used as chemical markers for variety identification. For instance, Coliris contains caffeic and caftaric acids, and it is the only hybrid with those components. These results give us a first insight of the concentration and specific phenolic profile in these four new hybrids, showing their variability over the different vintages.

References

Paire, C., Dolet, M.-A., Hannin, H., Samson, A., Olivier, V., Chervin, C., Geffroy, O., Cheriet, F. (2024). History of breeding programmes for fungus resistant grape varieties in Europe, France and the Occitanie region. OENO One. https://doi.org/10.20870/IVES-TR.2024.8262;https://hal.inrae.fr/hal-04699298