 IVES 9 IVES Conference Series 9 Macrowine 9 Macrowine 2021 9 Grapevine diversity and viticultural practices for sustainable grape growing 9 Exploring the effect of ripening rates on the composition of aroma and phenolic compounds in Cabernet-Sauvignon wines

Exploring the effect of ripening rates on the composition of aroma and phenolic compounds in Cabernet-Sauvignon wines

Abstract

AIM: The study of cultural practices to delay ripening and the characterization of their effect on wine composition is important in the mitigation of accelerated ripening caused by higher temperatures and frequent water stress events. The desynchronization between sugar accumulation and anthocyanins and organic acids during advanced ripening reported in previous studies frequently results in sub-optimal phenolic and aromatic maturity at the targeted sugar levels for winemaking. In this study, the effect of different rates of ripening on the chemistry of Cabernet Sauvignon wines was studied to explore if delayed ripening would result in higher quality wines.

METHODS: Fruit sugar accumulation rates were manipulated by means of crop load manipulation treatments and late season irrigation. Fruit was harvested at 26 °Brix and submitted to small-lot research winemaking. The basic chemistry and the composition of phenolic and aroma compounds were analyzed in the final wines.

RESULTS: The vineyard treatments returned three kinetics of sugar accumulation. A faster sugar accumulation (1 week earlier) was obtained by reducing crop load while a combination of crop removal and late season irrigation delayed ripening (2 weeks later) compared to untreated vines. Such effects of crop load and late season irrigation were already reported previously. In the final wines, there were little or no changes in the basic chemistry in response to the ripening rate. Crop load affected mainly the profile of wine aroma compounds, including both grape-derived and fermentation-derived compounds. On the other hand, an increase of irrigation late in the season led to an increase in phenolic compound levels, resulting in improved color and mouthfeel characteristics. Ripening was delayed by the interaction of cluster thinning and late season irrigation, which in turn led to higher concentrations of both volatile and phenolic compounds and further improvement of wine quality. In response to a slower sugar accumulation, an improvement of primary quality indicators of grape quality, such as lower green compounds and higher anthocyanins, translated into higher wine quality. Similar effects on these wine components were already observed in studies in which ripening was delayed by other means.

CONCLUSION

This study provides further confirmation that delayed ripening is beneficial to improve wine quality in late-ripening varieties. Amelioration of accelerated ripening is especially critical in warm and dry viticulture regions with long seasons, while the treatments investigated may not be necessary nor result in the same outcomes in cool wine regions. It was also shown that crop load and late season irrigation have a specific effect on aroma and phenolic compounds respectively, which deserves to be further explored in future studies.

DOI:

Publication date: September 2, 2021

Issue: Macrowine 2021

Type: Article

Authors

Pietro Previtali

The University of Adelaide and Australian Research Council Training Centre for Innovative Wine Production,Nick DOKOOZLIAN, E. & J. Gallo Winery and Australian Research Council Training Centre for Innovative Wine Production Luis SANCHEZ, E. & J. Gallo Winery Bruce PAN, E. & J. Gallo Winery Kerry WILKINSON, The University of Adelaide and Australian Research Council Training Centre for Innovative Wine Production Christopher FORD, The University of Adelaide and Australian Research Council Training Centre for Innovative Wine Production

Contact the author

Keywords

aroma compounds; delayed ripening; phenolic compounds; ripening rates; wine metabolites

Citation

The taste of color: how grape anthocyanin fractions affect in-mouth perceptions

Anthocyanins are responsible for the red wine color and their ability to condense with tannins is considered as a contributor in astringency reduction. However, recent studies showed the possibility of anthocyanins to influence directly the in-mouth perception of wines.

Influence of soil characteristics on vine growth, plant nutrient levels and juice properties: a multi-year analysis

Soil physical and chemical properties affect vine nutrition, as indicated by leaf and petiole nutrient content, in a way that may directly impact wine properties.

Integrated multiblock data analysis for improved understanding of grape maturity and vineyard site contributions to wine composition and sensory domains

Much research has sought to define the complex contribution of terroir (varieties x site x cultural practices) on wine composition. This investigation applied recent advances in chemometrics to determine relative contributions of vine growth, berry maturity and site mesoclimate to wine composition and sensory profiles of Shiraz and Cabernet Sauvignon for two vintages.

Soil management with cover crops in irrigated vineyards: effects in vine microclimate (cv. Malbec) grown in a terroir of Agrelo (Luján de Cuyo)

L’objectif de cette recherche a été de déterminer les effets de l’enherbement dans le microclimat de la vigne. On a comparé cinq couvertures de cycle végétatif différent en ce qui concerne l’entretien du sol sans culture par application d’herbicides. L’étude a été developpée dans un vignoble cv. Malbec conduit en haute espalier, situé en a terroir á Agrelo, Luján de Cuyo, Mendoza, Argentine. On a déterminé des paramètres micro climatiques:

Postveraison shoot trimming in Tannat and Merlot: preliminary results on yield components, plant balance and berry composition

There is currently a trend towards the production of wines with low alcohol content. To achieve this, grapes with low sugar content must be used. There are techniques at the vineyard level that can delay ripening and avoid excessive sugar accumulation without, a priori, affecting the final polyphenol content. Postveraison shoot trimming (PVST) is experimentally evaluated for these purposes, but its impact under Uruguayan climatic conditions with high interannual variability is not known. The aim of this work is to assess the PVST in Tannat and Merlot cultivars and their impact on yield components, plant balance and berry primary composition. In this study, two commercial vineyards of 10 years old Tannat and Merlot (grafted on SO4) at Canelones Department were selected. During the 2020-201 growing season, grapevines were submitted to PVST when grapes reached 15º Brix. In a randomized block, trimmed (T) and control (C) plants were evaluated with three repetitions each cultivar. Evaluation of the evolution of primary berry composition during ripening, measurement of yield components and plant balance were performed. For both cultivars, PVST did not affect yield components. Merlot reached 5.4 kg per plant and Tannat 7.1 kg, with not statistical significance between treatments. However, statistical differences were observed in terms of plant balance. In Merlot Ravaz Index reached a difference of 5.3 (12.0 in T and 6.7 in C) meanwhile Tannat reached 3.5 of statistical difference (13.7 in T and 10.2 in C). The tendency to imbalance for the treated plants had an impact on the final grape composition. Merlot grapes showed statistical difference in final total acidity (0.3 g of difference between treatments) while treatments impact final sugar content on Tannat grapes (10.0 g of difference between treatments). Further studies are needed to assess the impact of different canopy management techniques in our conditions.