 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

DNA-free genome editing confers disease resistance in grapevine varieties

The grapevine is facing significant challenges due to climate change, as rising temperatures impact its physiological traits and disrupt plant phenology.

Impact of microclimate on berry quality parameters of white Riesling (Vitis vinifera L.)

Knowledge has been accumulated on the impact of microclimate, in particular berry temperature and irradiation, for a wide range of red varieties. However, little research has been dedicated on the effects of the same factors on the quality of white grape varieties.

Under-vine management effects on grapevine production, soil properties and plant communities in South Australia

Under-vine (UV) management has traditionally consisted of synthetic herbicide use to limit competition between weeds and grapevines. With growing global interest towards non-synthetic chemical use, this study aimed to capture the effects of alternative UV management at two commercial Shiraz vineyards in South Australia, where the sole management variables were UV management since 2016. In adjacent treatment blocks, cultivation (CU) was compared to spontaneous vegetation (SV) in McLaren Vale (MV), and herbicide was compared to SV in Eden Valley (EV). Soil water infiltration rates were slower and grapevine stem water potential was lower in CU compared to SV in MV, with the latter having a plant community dominated by soursob (Oxalis pes-caprae) during winter; while in EV, there was little separation between the treatments. Yields were affected at both sites, with SV being higher in MV and HE being higher in EV. In MV, the only effect on grape must was a lower 13C:12C isotope ratio in CU, indicating greater grapevine water stress. In the grape must at EV, SV had higher total soluble solids, total phenolics, anthocyanins, and yeast available nitrogen; and lower pH and titratable acidity. Pruning weights were not affected by the treatments in MV, while they were higher in HE at EV. Assessments revealed that the differing soil types at the two sites were likely the main determinants of the opposing production outcomes associated with UV management. In the silty loam soil of MV, the higher yields in SV were likely due to more plant-available water, as a potential result of the continuous soil bio-pores formed by winter UV vegetation. Conversely, in the loamy sand soils of EV with a lower cation exchange capacity, the lower yields and pruning weights in SV suggest the UV vegetation competed significantly with the grapevines for available water and nutrients.

Exploring microbial interactions between Saccharomyces cerevisiae and non-Saccharomyces yeast starters in vinification

Winemaking is a complex microbial process involving the co-existence and interactions of various microorganisms [1].

ESTIMATING THE INITIAL OXYGEN RELEASE (IOR) OF CORK CLOSURES

Many factors influence aging of bottled wine, oxygen transfer through the closure is included. The maximum uptake of wine before oxidation begins varies from 60 mg.L-¹ to 180 mg.L-1 for white and red wines respectively [1].
The process of bottling may lead to considerable amounts of oxygen. The actual contribution of the transfer through the closure system becomes relevant at the bottle storage, but the amounts are small compared to prepacking operations [2] and to the total oxygen attained during filling.