Enological and nutraceutical potential of some grape varieties tolerant to downy mildew and powdery mildew

Abstract

AIM: Since 2012 the Veneto Region regulation (north-east Italy) allowed wine production using 20 hybrid grapevine varieties selected for their high tolerance to downy mildew and powdery mildew. Characterized by vigour, high grape productivity and low pesticide use, these varieties are suitable to develop sustainable viticulture in mountain areas located at medium altitudes. Project VINIRES (October 2018-November 2021) evaluates the oenological potential of four resistant vine varieties currently diffused at medium altitudes: Cabernet Cortis, Bronner, Souvignier gris, Johanniter. Study by metabolomics provides the complete qualitative and semi-quantitative profile of secondary metabolites in grape to estimate the enological potential of these varieties.

METHODS: Grapes harvested in 2019 and 2020 from vineyards located in Belluno province. Analyses performed by UHPLC/Q-TOF 40.000-resolution mass spectrometry. Targeted identification of the metabolites by using the homemade database GrapeMetabolomics (Flamini et al., 2013).

RESULTS: Cabernet Cortis: presence of anthocyanin diglucosides (Mv-diglu, Dp-diglu, Cy-diglu, Pt-diglu, Pn-diglu). Anthocyanin content comparable to V. Vinifera varieties such as Cabernet Sauvignon and Raboso Piave (Mattivi et al., 2006). Relevant presence of B-ring trisubstituted flavonols. Linalool and nerol pentosyl-hexoside as main aroma precursors. Bronner: high content of flavonoids such as quercetin (Q), taxifolin (T), and flavanones. Significant presence of monoterpene-diols glycosylated. Johanniter: high antioxidants such as rutin and Q-pentoside, significant T-pentoside. Main aroma precursor geraniol glycoside. Souvignier gris: presence of some anthocyanins (Cy-diglu, Cy-monoglu 3-fold than Cabernet Cortis) and stilbene compounds. Main aroma precursors: alpha-terpineol pentosyl-hexoside and vomifoliol glucoside (roseoside).

CONCLUSIONS:

Cabernet Cortis is suitable for production of wood-aged wines with floral notes. Bronner has semi-aromatic character and an interesting potential for producing fresh and fruity white wines. Johanniter, characterized by high geraniol, has high aptitude to produce aromatic sparkling wines. Souvignier gris is characterized by the presence of alpha-terpineol glycoside (floral aroma precursor) and stilbene phytoalexins correlated to the nutraceutical properties of wines.