Effect of elicitors and ripening moment on the phenolic composition of Monastrell

Abstract

Grapevine (Vitis vinifera L.) is a globally cultivated crop and economically significant, particularly in the wine industry (Varela et al., 2024). Climate change is already affecting vineyards and is expected to worsen (Averbeck et al., 2019; Dupuis and Knoepfel, 2011). Wine quality relies on the berry’s chemical composition, which depends on various metabolites and the synchronization of skin, seed, and pulp ripening. Strategies to enhance grape quality and address the uncoupling of technological and phenolic maturity include using elicitors, which induce secondary metabolite accumulation in response to stress signals (D’Onofrio et al., 2018). Numerous studies have explored the effects of different elicitors on grape phenolic compositions, but information on the impact of methyl jasmonate (MeJA) and grape marc extract on grape ripening is lacking. This research aims to provide insights into how elicitation affects the phenolic composition of grapes and wines, reducing the decoupling between phenolic and technological maturity.

This study was performed over two growing seasons (2022 and 2023) with Monastrell Vitis vinifera L.cvon Richter 110 rootstock, which were 7 and 10 years old and planted 2.5 x 3m in an experimental field located in Cehegín (Murcia, Spain). Three treatments were carried out, each in triplicate, at veraison and one week later, with 10 vines per replicate: (i) control (water), (ii) MeJA (10 mM), and (iii) grape marc extract (10 g/L). Grapes were harvested at two ripening moments when they reached 21ºBrix and 23ºBrix, respectively. Different chemical and chromatographic analyses were carried out to evaluate the quality of grapes and wines at harvest and at the end of alcoholic fermentation, respectively.

The results showed how the degree of maturity influenced the different parameters measured. Total anthocyanin content in grapes was higher for all the factors studied—treatment, degree of ripening, and vintage—at 23ºBrix, not showing differences among treatments at 21ºBrix; however, at 23ºBrix, the highest total anthocyanin content was observed in MeJA-treated grapes, and the lowest in marc-treated grapes. Regarding the results obtained for anthocyanins in wines, the differences found were much smaller than in grapes. With respect to flavonols in grapes, treatments did not have any effect, although the highest flavonol content was obtained in control grapes matured at 23ºBrix. However, in wines, the results for flavonols were more pronounced than in grapes, with significant differences found between treatments, maturity, and season.

References

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