GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 GiESCO 2019 9 Climate change 9 Riesling aroma composition in light of changing global temperatures – delving into the effects of warmer nights on the volatile profile of riesling grapes

Riesling aroma composition in light of changing global temperatures – delving into the effects of warmer nights on the volatile profile of riesling grapes

Abstract

Context and purpose of the study: Climate is a key parameter when the modulation of berry and subsequent wine composition is considered. Recent decades have already seen an increase in global surface temperatures, with a more pronounced effect on night temperatures. In Australia, very warm monthly minimum temperatures (two standard deviations higher than the historical average) increased from a 2% to 11 % frequency of occurrence, and very cool monthly night temperatures have declined by about a third (Barlow and Daly, 2017). Night time temperatures are known to influence transcriptomic responses in ripening grapes (Rienth et al., 2014), however, the effect on grape chemical composition, in particular on the aroma compounds, remains to be elucidated. Aroma compounds such as the terpenes and norisoprenoids are key to the quality of white wine varieties such as Riesling. Understanding both the synthesis and loss of these desirable compounds due to the effects of warmer night temperatures, is critical to understanding the need for implementation of suitable mitigation strategies to help cope with the effects of warming projected in the future.

Materials and Methods: Four sites in the Canberra wine region (Australian Capital Territory and New South Wales, Australia) were chosen based on climatic data and, historic cool night index. As such, sites were catalogued as having either warmer, cooler or intermediate temperature nights. Temperature, humidity and light sensors were installed from the véraison stage to monitor meso‐ and microclimatic parameters throughout the ripening period. Berries were collected every two weeks from véraison until commercial harvest for chemical analysis. Midday stem water potential was also measured at sampling to assess water stress levels. Chemical analyses included total soluble sugars, titratable acidity, pH, yeast assimilable nitrogen, carotenoids, and free and bound volatile compounds.

Results: Higher temperature summations significantly depressed the synthesis of important aroma compounds such as norisoprenoids and terpenes, with carotenoid concentrations also being significantly decreased. Conversely, the concentration of aldehydes such as E-2‐octenal and E-2‐nonanal were positively correlated with higher temperature summation throughout the overall ripening season. Night temperature appeared to have a more pronounced effect, particularly on the synthesis of terpenes, during the later stages of berry development, as previously observed by Rienth et al. (2014). At harvest, warmer night temperatures resulted in lower concentrations of terpenes (e.g. linalool and α‐ terpineol) and the C6 alcohols (e.g. 1‐hexanol) whilst a direct correlation to heat summation was less significant. 

DOI:

Publication date: June 19, 2020

Issue: GiESCO 2019

Type: Article

Authors

Joanna M. GAMBETTA1, John BLACKMAN1, Andrew HALL2, Leigh M. SCHMIDTKE1, Bruno HOLZAPFEL1,3

(1) National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW 2560, Australia
(2) Institute for Land, Water and Society, Charles Sturt University, Albury, NSW 2640, Australia
(3) New South Wales Department of Primary Industries, Wagga Wagga, Australia

Contact the author

Keywords

 Riesling, climate, night temperature, chemical composition, volatiles, carotenoids

Tags

GiESCO 2019 | IVES Conference Series

Citation

Related articles…

About long time and vine quality modelisation e pistemological appro ach to geographical viticulture

This work began as an intellectual game, in order to discuss the notion of wine quality in terms of terroir and territory spatial structure. Vine and wine quality has long been questioned by scientists. Each discipline approaching it with his own tools.

Efficiency of alternative chemical and physical treatments in reducing Brettanomyces Bruxellensis from oak wood

Oak barrels form an integral part of wine production, especially that of high quality wines. However, due to its porosity, wood presents an ecological niche for microbial proliferation and is highly susceptible to microbial spoilage which could cause considerable economic losses. Brettanomyces bruxellensis, the most commonly encountered microorganism responsible for spoilage during barrel ageing, can remain in barrels after barrel sanitation to contaminate new batches of wine after refilling. Therefore, effective sanitation treatments are of utmost importance to prevent recurring wine spoilage.

Characterisation of viticultural and oenological practices in two French AOC in the middle Loire Valley: comparison of different methods to extract information from a survey among winegrowers

The type of wine is determined by environmental, plant materials and human factors. These factors are numerous and interact together, which makes it difficult to determine the hierarchy of their effects

Influence of the agronomic management on the aroma of Riesling wines

Nitrogen fertilisation of grapevines is known to influence not only plant development and production yield, but also yeast assimilable nitrogen (YAN). This parameter is related to the growth of yeast

Caracterización de suelos de la comarca Tacoronte-Acentejo

La comarca Tacoronte-Acentejo, con una extensión cultivada de 2.422 has. concentra un 20% de los viñedos de Canarias.