IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Botrytis cinerea: Coconut or Catastrophe? Quantification of γ-Nonalactone in Botrytised and Non-Botrytised New Zealand Wines

Botrytis cinerea: Coconut or Catastrophe? Quantification of γ-Nonalactone in Botrytised and Non-Botrytised New Zealand Wines

Abstract

g-Nonalactone has been identified as a significant contributor to the aroma profile of a range of wines and is associated with stonefruit and coconut descriptors. The exact route of g-nonalactone biosynthesis in wine has not been fully elucidated; however, precursors including 4-oxononanoic acid, linoleic acid, 13-hydroxyoctadeca-9,11-dienoic acid (13-HODE) and 9-hydroxyoctadeca-10,12-dienoic acid (9-HODE) have been identified in incubation experiments. Wines produced from grapes infected with “noble rot” caused by Botrytis cinerea fungus generally show higher concentrations of g-nonalactone compared to non-botrytised white wines, but the relative contribution of potential formation pathways has not been elucidated. To assess the effect of linoleic acid on the production of g-nonalactone in wine, fermentations with and without added linoleic acid were carried out in synthetic grape must (SGM) at 28 °C using commercial Saccharomyces cerevisiae EC1118. Prior to g-nonalactone quantitation in the finished wines and in a subset of six Australian and New Zealand commercial wines, several routes for the synthesis of a deuterated analogue of g-nonalactone were attempted, before the deuterated d6-analogue of g-nonalactone from its non-deuterated analogue was produced successfully. Subsequently, attempts were made to utilise the d6-analogue as an internal standard for the measurement of g-nonalactone using gas chromatography-mass spectrometry. However, the synthetic deuterated g-nonalactone analogue proved to be an inappropriate internal standard for this purpose, due to incomplete incorporation of deuterium atoms. 2-Octanol was instead used as a surrogate internal standard. g-Nonalactone was successfully identified (above the limit of detection, 4.12g/L) in two commercial New Zealand botrytised wine samples, and one fermentation sample to which linoleic acid (132 mg/L) had been added. This suggests a possible link between the effect of Botrytis cinerea and/or linoleic acid, and increased levels of g-nonalactone in wine. The promising results in these preliminary experiments have led to an improved internal standard being sought out for the quantification of g-nonalactone in wine, and further investigation of its biosynthesis. A 13C4-labelled g-nonalactone analogue was successfully synthesized based on a previous method, with four 13C atoms being introduced into the molecule via two Wittig olefination steps. This standard will be used for a much larger survey of approximately 40 botrytised and non-botrytised New Zealand wines, in addition to further fermentation experiments assessing the effects of the addition of a wider range of putative precursors.

DOI:

Publication date: June 24, 2022

Issue: IVAS 2022

Type: Poster

Authors

Miller Gillean1, Fedrizzi Bruno1, Barker David1, Pilkington Lisa1 and Deed Rebecca1

1The University of Auckland, School of Chemical Sciences

Contact the author

Keywords

Lactones, Botrytis, White wine, New Zealand, GC-MS

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Elucidating vineyard site contributions to key sensory molecules: Identification of correlations between elemental composition and volatile aroma profile of site-specific Pinot noir wines

The reproducibility of elemental profile in wines produced across multiple vintages has been previously reported using grapes from a single scion clone of Vitis vinifera L. cv. Pinot noir. The grapevines were grown on fourteen different vineyard sites, from Oregon to southern California in the U.S.A., which span distances from approximately hundreds of meters to 1450 km, while elevations range from near sea level to nearly 500 m. In addition, sensorial (i.e. aroma, taste, and mouthfeel) and chemical (i.e. polyphenolic and volatile) differences across the different vineyard sites have also been observed among these wines at two aging time points. While strong evidence exists to support that grapes grown in different regions can produce wines with unique chemical and sensorial profiles, even when a single clone is used, the understanding of growing site characteristics that result in this reproducible differentiation continues to emerge. One hypothesis is that the elemental profile that a vineyard site imparts to the grape berries and the resulting wine is an important contributor to this differentiation in chemistry and sensory of wines. For example, various classes of enzymes that catalyze the formation of key aroma compounds or their precursors require specific metals. In this work, we begin to report correlations between elemental and volatile aroma profiles of site-specific Pinot noir wines, made under standardized winemaking conditions, that have been previously shown to be distinguished separately by these chemical analyses.

A predictive model of spatial Eca variability in the vineyard to support the monitoring of plant status

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Terroir traceability in grapes, musts and wine: results of research on Gewürztraminer and Sauvignon Blanc grape varieties in northern Italy

In the study of terroir, a separate analysis of its many component factors can be of great help in accurately identifying a vineyard’s natural elements that impact wine quality and typicity. This research used a dedicated pluri-disciplinary approach to investigate the ecological characteristics, including geology and geographical features, of 14 vineyards that produce Gewürztraminer and Sauvignon Blanc cultivars in the alpine Alto Adige DOC wine region. Both the geopedological method using Vineyards Geological Identity (VGI) and the new Solar Radiaton Identity (SRI) topoclimatic classification method were used to provide analytical measurements and qualitative/quantitative characterisations. In addition, wide-ranging targeted and untargeted oenological and chemical analyses were carried out on grapes, musts and wines to correlate the soils’ geomineral and physical conditions with the biochemical properties of their fruits and wines. The research identified strong correlations between vineyard geo-identity and wine biofingerprint, confirming a mineral traceability of strontium rubidium ratio and some minerals distinctive to the local geology, such as K, Ca, Ag, Ba and Mn.  The study also discovered that particular geomineral and physical soil conditions of the studied vineyards are related to the different amount of amino acids, primary varietal aromas and polyphenols found in grapes, musts and wines. The research confirmed that winemaking technologies support oenological quality, although in some cases, human practices can overpower certain characteristic elements in wine, erasing the typical imprint left by the vineyards’ natural terroir, which becomes less traceable. Terroir abiotic ecological factors and vineyard identity can be classified in detail using the new VGI and SRI analysis methods to discover interrelationships between geo-pedological and topoclimatic conditions that impact wine quality. These methods are also helpful in identifying which ecological elements are exclusive to a particular vineyard or wine sub-region.

Exploring resilience and competitiveness of wine estates in Languedoc-Roussillon in the recent past: a multi-level perspective

The Languedoc-Roussillon wineries are facing a decline in wine yields particularly PGI yields due to many factors. Climate change is just ones, but is expected to increase in the future. There is also structurally a large heterogeneity of yield profiles among terroirs, varieties and strategies. This work investigates the link between yield, competitiveness and resilience to explore how resilient winegrowers have been in the recent past. To this end two approaches have been combined; (i) an accountancy database analysis at estate scale and (ii) municipality level competitiveness analysis. A new resilience indicator that characterizes the capacity of an estate to absorb yield variation is also defined. The FADN database between 2000 and 2018 of ex-Languedoc-Roussillon (France) and other data are used to analyse the current situation and the past evolution of competitiveness and resilience by type of estate (type of farm: PGI and/or PDO & type of commercialization: bulk and/or bottles). The net margin, which defines competitiveness, is not correlated to yield for all types but depends on the type of commercialization and the level of specialisation. The resilience indicator shows that the net margin of estates specialized in PGI is particularly sensitive to yield declines. We also show that price evolutions seem to compensate the effect of yield losses for the majority of types. Municipality scale analysis shows the links between local pedoclimate, yield, commercialization strategies and price. Overlapping a PDO with a PGI does not always increase a municipality’s PGI competitiveness. It is difficult to make links between causes and effects due to the complexity of the wine production system. Production diversification may be a solution. Resorting to the two level of analysis helps resolving the data gap that is necessary to explore the links between yield and economic performance of the wine estates in the long term.

Phenolic composition of Tempranillo Blanco grapes changes after foliar application of urea

Our research aimed to determine the effect and efficiency of foliar application of urea on the phenolic composition of Tempranillo Blanco grapes. The field experiment was carried out in 2019 and 2020 seasons and the plot was located in D.O.Ca Rioja (North of Spain). The vineyard was Vitis vinifera L. Tempranillo Blanco and grafted on Richter-110 rootstock. The treatments were control (C), whose plants were sprayed with water and three doses of urea: plants were sprayed with urea 3 kg N/ha (U3), 6 kg N/ha (U6) and 9 kg N/ha (U9). The applications were performed in two phenological stages, pre-veraison (Pre) and veraison (Ver). Also, each of the treatments was repeated one week later. Control and treatments were performed in triplicate and arranged in a randomised block design. Grapes were harvested at optimum ripening stage. High-performance liquid chromatography was used to analyse the phenolic composition of the grapes. Finally, the results obtained from the analytical determinations – flavonols, flavanols and non-flavonoid (hydroxybenzoic acids, hydroxycinnamic acids and stilbenes) – were studied statistically by analysis of variance. The results showed that, in 2019, U6-Pre and U9-Pre treatments increased the hydroxybenzoic acid content in grapes, and also all foliar treatments applied at Pre enhanced the stilbene concentration. Moreover, U3-Ver was the only treatment that rose flavonol and stilbene contents in the Tempranillo Blanco grapes. In 2020, all treatments applied at Pre enhanced the flavonol concentration in grapes. Furthermore, U3-Pre and U9-Pre treatments increased stilbene content in grapes. Nevertheless, the hydroxybenzoic acid content was improved by U6-Ver and U9-Ver and besides, hydroxycinnamic acid concentration in grapes was increased by all treatments applied at Ver. In conclusion, the lower and highest dose of urea (U3 and U9), applied at pre-veraison, were the best treatments to improve the Tempranillo Blanco grape phenolic composition.