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…

Étude des potentialités des terroirs viticoles: une démarche globale en zone A.O.C. L’exemple des Côtes du Rhône

Depuis près d’une quinzaine d’années, l’Appellation d’Origine Contrôlée (A.O.C.) Côtes du Rhône a engagé un vaste programme afin de mieux connaître et valoriser les potentialités des différents terroirs qui la composent.

Heatwaves and grapevine yield in the Douro region, crop model simulations

Heatwaves or extreme heat events can be particularly harmful to agriculture. Grapevines grown in the Douro winemaking region are particularly exposed to this threat, due to the specificities of the already warm and dry climatic conditions. Furthermore, climate change simulations point to an increase in the frequency of occurrence of these extreme heat events, therefore posing a major challenge to winegrowers in the Mediterranean type climates. The current study focuses on the application of the STICS crop model to assess the potential impacts of heatwaves in grapevine yields over the Douro valley winemaking region. For this purpose, STICS was applied to grapevines using high-resolution weather, soil and terrain datasets over the Douro. To assess the impact of heatwaves, the weather dataset (1989-2005) was artificially modified, generating periods with anomalously high temperatures (+5 ºC), at certain onset dates and with specific durations (from 5 to 9 days). The model was run with this modified weather dataset and results were compared to the original unmodified runs. The results show that heatwaves can have a very strong impact on grapevine yields, strongly depending on the onset dates and duration of the heatwaves. The highest negative impacts may result in a decrease in the yield by up to -35% in some regions. Despite some uncertainties inherent to the current modelling assessment, the present study highlights the negative impacts of heatwaves on viticultural yields in the Douro region, which is critical information for stakeholders within the winemaking sector for planning suitable adaptation measures.

Application of antagonistic Metschnikowia strains against Botrytis cinerea in vineyards 

Less and less chemical plant protection products are approved by the E U. Plant pathogenic fungi become increasingly resistant to the active ingredients that have been around for a long time. Besides, there is a valid demand for effective products that can be applied in organic cultivation.
We examined Metschnikowia strains under laboratory conditions in order to find effective strains against B. cinerea. The antimicrobial mechanism of these yeasts is based on the competition for the ferric ions from the environment. Metschnikowia cells release the pulcherriminic acid which chelates with Fe3+, forming the pigment pulcherrimin.

Interaction between the enzymes of central carbon metabolism and anthocyanin biosynthesis during grape berry development

Primary and secondary metabolites are major components of grape quality and wine typicity. Their accumulation is interconnected through a complex metabolic network, which is still not well understood. This study aims to investigate how the enzymes of central carbon metabolism interact with anthocyanin biosynthesis during grape berry development: does the accumulation of anthocyanins, which represents a non-negligible diversion of carbon metabolic fluxes, require reprogramming of central enzymes or is it controlled downstream of central metabolism? To this end, 23 enzymes involved in central carbon metabolism pathways have been analyzed in the berries of 3 grape cultivars, which have close genetic background but distinct temporal dynamics of anthocyanin accumulation.

New Insights into Wine Color Analysis: A Comparison of Analytical Methods and their Correlation with Sensory Perception

wo spectrophotometric methods are recommended by the Organisation Internationale de la vigne et du vin (OIV). The first is the method after Glories, were the absorbances at 420 nm, 520 nm and 620 nm are measured (OIV 2006a).