IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 The interaction between wine polyphenolic classes and poly-L-proline is impacted by oxygen

The interaction between wine polyphenolic classes and poly-L-proline is impacted by oxygen

Abstract

Oxygen plays a key role in the evolution of wine chemistry, within the non-volatile matrix. Polyphenol composition and structure, as well as the process of tannin polymerisation are directly impacted by oxidation, and this can occur during both fermentation and ageing. Polyphenols play an important role in red wine and exhibit a wide diversity in their structure and properties. They are responsible for wine colour, texture and taste (astringency, bitterness) and exhibit some health properties. The principal class of non-flavonoid polyphenolic compounds are the phenolic acids and stilbenes. Among the flavonoids, anthocyanins and tannins are the major structural classes. The aim of this study was to characterise the detailed response of wine polyphenolic structure and composition to an oxygen treatment applied during fermentation. A specific focus was to determine the interaction of discrete polyphenolic classes with poly-L-proline (PLP). A control Shiraz wine was prepared under reductive conditions during fermentation, in triplicate. To the same grape source, an aeration treatment was initiated on day 3 following a 1.8 °Bé decrease for 48 h at 5 L/min, also in triplicate.  After a 12-month ageing period, wines were fractionated where: F1 = Phenolic acids, F2 = flavan-3-ol monomers, F3 = flavan-3-ol oligomers, F4 = anthocyanins, pyranoanthocyanins; and F5 = polymeric proanthocyanidins, pigmented proanthocyanins and other derived complexes. The composition of fractions F1 to F4 was verified by LC-MS, and F5 was characterised by a combination of analytical techniques specific to proanthocyanidins. The interaction between the polyphenol fractions and PLP was measured by isothermal titration calorimetry (ITC). A strong binding interaction was observed between F1, the phenolic acids, and PLP by ITC, and was not affected by the oxygen treatment. In fact, a strong hydrophobic interaction and hydrogen bonding was implicated in the interaction. It was found that for fractions F2 and F3, no binding events with PLP were observed by ITC, irrespective of the oxygen level applied. Stronger binding events with PLP were observed for the F4 and F5 polyphenolic fractions, but interestingly, only in those prepared from wines which had oxygen treatment. Moreover, hydrophobic interaction and hydrogen bonding was detected just for the oxygen treatment for F4 and F5. Contrary to expectation, no binding with PLP could be detected for F4 and F5 from the control wine. Further investigation of the properties of the fractions was conducted to account for the differences observed, including their composition, hydrophobicity and aggregation. This presentation will provide new insights into the potential role of discrete polyphenolic classes in driving in-mouth sensory properties, like astringency, which might be elicited following binding with proline-rich salivary proteins.

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Jouin Alicia1, Falconer Robert J.2, Waterlot Aude3, Day Martin1, Schmidt Simon1 and Bindon Keren1

1The Australian Wine Research Institute, PO Box 197, Glen Osmond, South Australia, 5064, Australia 
2Department of Chemical Engineering and Advanced Materials, University of Adelaide, Adelaide, SA, 5005, Australia
3Department of Food Science and Human Nutrition, Courtesy Faculty, Horticulture, Iowa State University, 2567 Food Sciences Building, 536 Farm House Lane, Ames, IA 50011, USA

Contact the author

Keywords

Tannins, Anthocyanins, Oxygen, Isothermal Titration Calorimetry, Astringency

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Adapting the vineyard to climate change in warm climate regions with cultural practices

Since the 1980s global regime shift, grape growers have been steadily adapting to a changing climate. These adaptations have preserved the region-climate-cultivar rapports that have established the global trade of wine with lucrative economic benefits since the middle of 17th century. The advent of using fractions of crop and actual evapotranspiration replacement in vineyards with the use of supplemental irrigation has furthered the adaptation of wine grape cultivation. The shift in trellis systems, as well as pruning methods from positioned shoot systems to sprawling canopies, as well as adapting the bearing surface from head-trained, cane-pruned to cordon-trained, spur-pruned systems have also aided in the adaptation of grapevine to warmer temperatures. In warm climates, the use of shade cloth or over-head shade films not only have aided in arresting the damage of heat waves, but also identified opportunities to reduce the evapotranspiration from vineyards, reducing environmental footprint of vineyard. Our increase in knowledge on how best to understand the response of grapevine to climate change was aided with the identification of solar radiation exposure biomarker that is now used for phenotyping cultivars in their adaptability to harsh environments. Using fruit-based metrics such as sugar-flavonoid relationships were shown to be better indicators of losses in berry integrity associated with a warming climate, rather than solely focusing on region-climate-cultivar rapports. The resilience of wine grape was further enhanced by exploitation of rootstock × scion combinations that can resist untoward droughts and warm temperatures by making more resilient grapevine combinations. Our understanding of soil-plant-atmosphere continuum in the vineyard has increased within the last 50 years in such a manner that growers are able to use no-till systems with the aid of arbuscular mycorrhiza fungi inoculation with permanent cover cropping making the vineyard more resilient to droughts and heat waves. In premium wine grape regions viticulture has successfully adapted to a rapidly changing climate thus far, but berry based metrics are raising a concern that we may be approaching a tipping point.

Bioclimatic shifts and land use options for Viticulture in Portugal

Land use, plays a relevant role in the climatic system. It endows means for agriculture practices thus contributing to the food supply. Since climate and land are closely intertwined through multiple interface processes, climate change may lead to significant impacts in land use. In this study, 1-km observational gridded datasets are used to assess changes in the Köppen–Geiger and Worldwide Bioclimatic (WBCS)

‘Cabernet Sauvignon’ (Vitis vinifera L.) berry skin flavonol and anthocyanin composition is affected by trellis systems and applied water amounts

Trellis systems are selected in wine grape vineyards to mainly maximize vineyard yield and maintain berry quality. This study was conducted in 2020 and 2021 to evaluate six commonly utilized trellis systems including a vertical shoot positioning (VSP), two relaxed VSPs (VSP60 and VSP80), a single high wire (SH), a high quadrilateral (HQ), and a guyot (GY), combined with three levels of irrigation regimes based on different crop evapotranspiration (ETc) replacements, including a 25% ETc, 50% ETc, and 100% ETc. The results indicated SH yielded the most fruits and accumulated the most total soluble solids (TSS) at harvest in 2020, however, it showed the lowest TSS in the second season. In 2020, SH and HQ showed higher concentrations in most of the anthocyanin derivatives compared to the VSPs. Similar comparisons were noticed in 2021 as well. SH and HQ also accumulated more flavonols in both years compared to other trellis systems. Overall, this study provides information on the efficacy of trellis systems on grapevine yield and berry flavonoid accumulation in a currently warming climate.

Modeling island and coastal vineyards potential in the context of climate change

Climate change impacts regional and local climates, which in turn affects the world’s wine regions. In the short term, these modifications rises issues about maintaining quality and style of wine, and in a longer term about the suitability of grape varieties and the sustainability of traditional wine regions. Thus, adaptation to climate change represents a major challenge for viticulture. In this context, island and coastal vineyards could become coveted areas due to their specific climatic conditions. In regions subject to warming, the proximity of the sea can moderate extremes temperatures, which could be an advantage for wine. However, coastal and island areas are particular prized spaces and subject to multiple pressures that make the establishment or extension of viticulture complex.
In this perspective, it seems relevant to assess the potentialities of coastal and island areas for viticulture. This contribution will present a spatial optimization model that tends to characterize most suitable agroclimatic patterns in historical or emerging vineyards according to different scenarios. Thanks to an in-depth bibliography a global inventory of coastal and insular vineyards on a worldwide scale has been realized. Relevant criteria have been identified to describe the specificities of these vineyards. They are used as input data in the optimization process, which will optimize some objectives and spatial aspects. According to a predefined scenario, the objectives are set in three main categories associated with climatic characteristics, vineyards characteristics and management strategies. At the end of this optimization process, a series of maps presents the different spatial configurations that maximize the scenario objectives.

Grape must quality and mesoclimatic variability in Fruška Gora wine-growing region, Serbia

The Fruška Gora mountain is a traditional wine-growing region in Serbia situated in the Pannonian Basin. Due to such a position, the vicinity of the Danube River and the presence of concave configuration, it is suitable for grape production. This paper provides analyses of spatial variations in meteorological parameters and grape juice quality within Fruška Gora wine region over three consecutive vintages (2018-2020). The examined period can be defined as warm with cool nights during September (AVG 18,9°C; GDD 1918°C; CI 12°CF) and with the presence of mesoclimatic variability. The East part of the study area was somewhat drier and hotter compared to other parts of the region. The analyses of grape must samples (190 in total) of five cultivars (Cabernet-Sauvignon, Merlot, Chardonnay, Sauvignon blanc and Grašac (Welschriesling)) commonly grown across the region (19 sites), were performed using Fourier Transform Infrared Technology (FTIR). Among all cultivars, Sauvignon blanc was harvested first in the East area (DOY=246±5, GDD at harvest=1552±74, 22.2±0.7 °Brix), while the latest harvest was recorded for Cabernet-Sauvignon in the West (DOY=283±5, GDD at harvest=1936±187, 23.4±1.0 °Brix ). Both the red and white cultivars had higher acidity and YAN in the grape must if the vines were grown in the North and East compared to South and West areas. According to PCA analysis, Grašac showed the lowest variation in grape must chemical composition. Thus, the results confirm that Grašac is the most stable cultivar in Fruška Gora. All monitored cultivars reached technological fruit ripeness by the end of the growing season. However, it was difficult to reach full ripeness of red cultivars, mostly beacuse of uncoupling of technolocical and phenolic ripeness. Thus, Cabernet-Sauvignon had higher variations in GDD sums at harvest compared to other cultivars, which probably increased variations in grape must quality.