Flavonol and anthocyanin potential of Spanish minority grapes and its relationship with wine colour

Abstract

Global climate change is currently affecting vine phenology and causing a decoupling between technological and phenolic maturity of the grapes [1]. Wine industry has to face the challenge of making quality wines from grapes with an unbalanced phenolic composition. Minority autochthonous grape varieties are nowadays attracting the attention of scientists and oenologists due to their greater adaptation potential to the changing environmental conditions [2]. In the Spanish “Castilla y León” region, a significant number of minority grape varieties have been properly identified and conserved in a Germplasm Bank [3]. Among them, some show a good oenological potential [4]. However, their recovery to produce quality wines must be supported by a deep knowledge of their phenolic composition, since these compounds are directly related to wine colour and astringency. Regarding colour, the anthocyanin potential of 7 of these minority varieties has been recently studied in our laboratory. However, wine colour will also depend on the copigmentation interactions occurring between these anthocyanins and copigments present in wine, among which, the flavonols are the most effective ones. Thus, the main objective of the present study was to determine the skin’s flavonol composition of these varieties by means of HPLC-DAD-MSⁿ and to find if there is any relationship between this composition, the grape anthocyanin composition and the colour expressed by the wines made from these grapes. Furthermore, this study also aims at establishing if the varietal typicity is maintained when the grapes are grown in regions different from their native ones. Total flavonol contents ranged from 80 to 300 mg/kg of grape and were, in most cases, greater than the contents reported for common varieties such as Tempranillo or Syrah [5]. The growing location affected flavonol total content and profile, but varietal typicity was quite maintained among locations. The ratio methoxylated/non-methoxylated flavonols was found to be a useful varietal marker. The results of the CIELAB colour measurements in the wines made from these grapes showed that the darkest wines with the greatest bluish hues were not those elaborated with the grapes with the greatest anthocyanin potential, but those showing greater percentages of methoxylated flavonols. These results highlight the usefulness of studying the flavonol composition along with that of anthocyanins in grape skins to reach a deeper knowledge of the potential of grapes to produce wines with better colour characteristics.

References

[1] Mira de Orduña, R. (2010). Food Res. Int., 43, 1844-1855.

[2] Wolkovich, E.M., García de Cortázar-Atauri, I., Morales-Castilla, I., Nicholas, K.A., Lacombe, T. (2018). Nat. Clim. Change, 8, 29-37.

[3] Rubio, J.A., Yuste, J., Arranz, C., Martín, J.P., Ortiz, J.M. (2005). Vit. Enol. Prof. 99, 5-17.

[4] Pérez-Magariño, S., Bueno-Herrera, M., Curiel-Fernández, M., Martín, A., Barajas, E., Rubio, J.A. (2022). Abstract Book of GIENOL 2022.

[5] Castillo-Muñoz, N., Gómez-Alonso, S., García-Romero, E., Hermosín-Gutiérrez, I. (2007). J. Agric. Food Chem., 55 (3), 992-1002.