Macrowine 2021
IVES 9 IVES Conference Series 9 From precursor identification to the study of the distribution of 3-methyl-2,4-nonanedione in red wines and spirits

From precursor identification to the study of the distribution of 3-methyl-2,4-nonanedione in red wines and spirits

Abstract

Prematurely aged red wines are marked by intense prune and fig aromatic nuances that dominate the complex bouquet that can be achieved through bottle aging. This oxidation off-flavor is, in part, caused by the presence of 3-methyl-2,4-nonanedione (MND).1 It is interesting to note that similar aromas are also detected in aged spirits. Despite its strong sensory impact in red wines, the precursors of this diketone were not well described.

So, first investigations were performed in order to quantify this compound in young and aged spirits in order to explain these nuances. In addition, determination of MND precursors in red wines as well as the study of oxidation mechanisms on their evolutions will improve our ability to understand its formation pathway in alcoholic beverages.

The first step of this work aimed at identifying a precursor of MND in grapes and wines. Based on the MND distribution in grapes, in young and old wines we hypothesized that ketols might be precursors of this diketone. We describe the chemical synthesis of 2-hydroxy-3-methylnonan-4-one (syn- and anti-ketol) as well as their identification in wines. MND and ketols were quantified by SPME-GC-MS (CI, MeOH) using SIS and MS/MS mode, respectively, in more than 150 Merlot and Cabernet Sauvignon wines from California, Bordeaux, and Switzerland. Oxidation experiments conducted in model wine and red wine demonstrated that ketols are able to produce MND. Based on these data, their role as MND precursor will be discussed. In addition, we also report first results concerning the origin of ketols in grapes and wines.

We also extended our investigations to spirits were old samples can develop similar dried plum aromas. We also report for the first time the distribution of MND in many spirits including Cognac, Armagnac, Brandy, Bourbon, Grappa, Rhum, Whisky. Highest levels were found in grappa (> 10 000 ng/L), exceeding its detection thresholds (100 ng/L). Sensory analysis experiments revealed that this compound contributes to the aroma of spirits. Assay of ketols in these samples revealed that they can be precursors of MND in spirits.

This project has improved our understanding of the formation and evolution of MND in wines, enabling more accurate predictions of the oxidative behavior and aging potential of red wines. In addition, we describe its first identification as well as its sensory impact in spirits

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Alexandre PONS

Université Bordeaux, ISVV, EA 4577, Unité de Recherche Œnologie, F-33882 Villenave d’Ornon, France, Seguin Moreau Cooperage, ZI Merpins, 16103 Cognac, France. Ana PETERSON, Université Bordeaux, ISVV, EA 4577, Unité de Recherche Œnologie, F-33882 Villenave d’Ornon, France. Fannie THIBAUD, Université Bordeaux, ISVV, EA 4577, Unité de Recherche Œnologie, F-33882 Villenave d’Ornon, France. Jean Charles MATHURIN, E. Rémy Martin & C°, Z.I, 16100 Merpins, France. Yannick LANDAIS, Université Bordeaux, ISM, CNRS UMR 5255, Talence, France. Philippe DARRIET, Université Bordeaux, ISVV, EA 4577, Unité de Recherche Œnologie, F-33882 Villenave d’Ornon, France. INRA, ISVV, USC 1366, Unité de Recherche Œnologie, F-33882 Villenave d’Ornon, France

Contact the author

Keywords

aging, red wines, oxidation, aroma, spirits, aroma precursor

Citation

Related articles…

Biodiversity in the vineyard agroecosystem: exploring systemic approaches

Biodiversity conservation and restoration are essential for guarantee the provision of ecosystem services associated to vineyard agroecosystem such as climate regulation trough carbon sequestration and control of pests and diseases. Most of published research dealing with the complexity of the vineyard agroecosystems emphasizes the necessity of innovative approaches, including the integration of information at different temporal and spatial scales and development of systemic analysis based on modelling. A biodiversity survey was conducted in the Franciacorta wine-growing area (Lombardy, Italy), one of the most important Italian wine-growing regions for sparkling wine production, considering a portion of the territory of 112 ha. The area was divided into several Environmental Units (EUs), defined as a whole vineyard or portion of vineyard homogenous in terms of four agronomic characteristics: planting year, planting density, cultivar, and training system. In each EU a set of compartments was identified and characterised by specific variables. The compartments are meteorology, morphology (altitude, slope, aspect, row orientation, and solar irradiance), ecological infrastructures and management. The landscape surrounding EU was also characterised in terms of land-use in a buffer zone of 500 m. For each component a specific methodology was identified and applied. Different statistical approaches were used to evaluate the method to integrate the information related to different compartments within the EU and related to the buffer zone. These approaches were also preliminarily evaluated for their ability to describe the contribution of biodiversity and landscape components to ecosystem services. This methodological exploration provides useful indication for the development of a fully systemic approach to structural and functional biodiversity in vineyard agroecosystems, contributing to promote a multifunctional perspective for the all wine-growing sector.

Towards a regional mapping of vine water status based on crowdsourcing observations

Monitoring vine water status is a major challenge for vineyard management because it influences both yield and harvest quality. It is also a challenge at the territorial scale for identifying periods of high water restriction or zones regularly impacted by water stress. This information is of major importance for defining collective strategies, anticipating harvest logistic or applying for irrigation authorisation. At this spatial scale, existing tools and methods for monitoring vine water status are few and often require strong assumptions (e.g. water balance model). This paper proposes to consider a collaborative collection of observations by winegrowers and wine industry stakeholders (crowdsourcing) as an interesting alternative. Indeed, it allows the collection of a large number of field observations while pooling the collection effort. However, the feasibility of such a project and its interest in monitoring vine water status at regional scale has never been tested.

The objective of this article is to explore the possibility of making a regional map of vine water status based on crowdsourcing observations. It is based on the study of the free mobile application ApeX-Vigne, which allows the collection of observations about vine shoot growth. This information is easy to collect and can be considered, under certain conditions, as a proxy for vine water status. This article presents the first results obtained from the nearly 18,000 observations collected by winegrowers and wine industry stakeholders during 2019, 2020 and 2021 seasons. It presents the vine shoot growth maps obtained at regional scale and their evolution over the three vintages studied. It also proposes an analysis of the factors that favoured the number of observations collected and those that favoured their quality. These results open up new perspectives for monitoring vine water status at a regional scale but above they provide references for other crowdsourcing projects in viticulture.

Assessment of climate change impacts on water needs and growing cycle on grapevine in three DOs of NE Spain

This study assessed the suitability of grapevine growing in three DOs (Empordà, Pla de Bages and Penedès) of Catalonia (NE Spain) over the 21st century. For this purpose, an estimation of water needs and agroclimatic and phenological indicators was made. Climate change impacts were estimated at 1 km pixel resolution using temperature and precipitation projections from several general circulation models (GCM) and two climate change scenarios: RCP 4.5 (stabilization scenario) and RCP 8.5 (worst-case scenario). Potential crop evapotranspiration (following FAO procedure) and a daily water balance considering soil water holding capacity were used to estimate actual evapotranspiration of vines and, finally, water needs. Dynamics would be similar in the three DOs studied although the magnitude of impact differs. Water needs would be 2 and 3 times greater (ranging from 0 to more than 1500 m3/ha) than current water needs at both climate change scenarios. Moreover, blooming date would advance from 3 to 6 weeks, harvest date from 1 to 2.5 months, resulting in growing cycles from 10 to 80 days shorter. It should also be noted that frost risk would decrease from 6 to 76%, the number of days with temperatures above 30ºC during ripening would rise from 48 to 500% and tropical nights (minimum temperature >20ºC) at ripening would increase from 28 to 150%, depending on the scenario and the DOs. The impacts of climate change in the three DOs could result in significant limitations for grapevine cultivation and wine production if adaptive strategies are not applied. This result could serve as a basis for the design of specific and particular adaptation strategies to improve and maintain vineyards in the DOs studied and could be extrapolated to similar DOs and regions.

Grape berry size is a key factor in determining New Zealand Pinot noir wine composition

Making high quality but affordable Pinot noir (PN) wine is challenging in most terroirs and New Zealand’s (NZ) situation is no exception. To increase the probability of making highly typical PN wines producers choose to grow grapes in cool climates on lower fertility soils while adopting labour intensive practices. Stringent yield targets and higher input costs necessarily mean that PN wine cost is high, and profitability lower, in line-priced varietal wine ranges. To understand the reasons why higher yielding vines are perceived to produce wines of lower quality we have undertaken an extensive study of PN in NZ. Since 2018, we established a network of twelve trial sites in three NZ regions to find individual vines that produced acceptable commercial yields (above 2.5kg per vine) and wines of composition comparable to “Icon” labels. Approximately 20% of 660 grape lots (N = 135) were selected from within a narrow juice Total Soluble Solids (TSS) range and made into single vine wines under controlled conditions. Principal Component Analysis of the vine, berry, juice and wine parameters from three vintages found grape berry mass to be most effective clustering variable. As berry mass category decreased there was a systematic increase in the probability of higher berry red colour and total phenolics with a parallel increase in wine phenolics, changed aroma fraction and decreased juice amino acids. The influence of berry size on wine composition would appear stronger than the individual effects of vintage, region, vineyard or vine yield. Our observations support the hypothesis that it is possible to produce PN wines that fall within an “Icon” benchmark composition range at yields above 2.5kg per vine provided that the Leaf Area:Fruit Weight ratio is above 12cm2 per g, mean berry mass is below 1.2g and juice TSS is above 22°Brix.

Simulating climate change impact on viticultural systems in historical and emergent vineyards

Global climate change affects regional climates and hold implications for wine growing regions worldwide. Although winegrowers are constantly adapting to internal and external factors, it seems relevant to develop tools, which will allow them to better define actual and future agro-climatic potentials. Within this context, we develop a modelling approach, able to simulate the impact of environmental conditions and constraints on vine behaviour and to highlight potential adaptation strategies according to different climate change scenarios. Our modeling approach, named SEVE (Simulating Environmental impacts on Viticultural Ecosystems), provides a generic modeling framework for simulating grapevine growth and berry ripening under different conditions and constraints (slope, aspect, soil type, climate variability…) as well as production strategies and adaptation rules according to climate change scenarios. Each activity is represented by an autonomous agent able to react and adapt its reaction to the variability of environmental constraints. Using this model, we have recently analyzed the evolution of vineyards’ exposure to climatic risks (frost, pathogen risk, heat wave) and the adaptation strategies potentially implemented by the winegrowers. This approach, implemented for two climate change scenarios, has been initiated in France on traditional (Loire Valley) and emerging (Brittany) vineyards. The objective is to identify the time horizons of adaptations and new opportunities in these two regions. Carried out in collaboration with wine growers, this approach aims to better understand the variability of climate change impacts at local scale in the medium and long term.