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…

Leaf vine content in nutrients and trace elements in La Mancha (Spain) soils: influence of the rootstock

The use of rootstock of American origin has been the classic method of fighting against Phylloxera for more than 100 years. For this reason, it is interesting to establish if different rootstock modifies nutrient composition as well as trace elements content that could be important for determining the traceability of the vine products. A survey of four classic rootstocks (110-Richter, SO4, FERCAL and 1103-Paulsen) and four new ones (M1, M2, M3 and M4) provided by Agromillora Iberia. S.L.U., all of them grafted with the Tempranillo variety, has been carried out during 2019. The eight rootstocks were planted in pots of 500 cc, on three soils with very different characteristics from Castilla-La Mancha (Spain). In the month of July, the leaves were collected and dried in a forced air oven for seven days at 40ºC. Then, the samples were prepared for the analysis determination, carried out by X-Ray fluorescence spectrometry. The results obtained showed that in the case of content in mineral elements in leaf, separated by soil type, we can report the importance of few elements such as Si, Fe, Pb and, especially, Sr. The rootstock does not influence the composition of the vine leaf for the studied elements that are the most important in determining the geochemical footprint of the soil. The influence of the soil can be discriminated according to some elements such as Fe, Pb, Si and, especially, Sr.

A spatial explicit inventory of EU wine protected designation of origin to support decision making in a changing climate

Winemaking areas recognized as protected designations of origin (PDOs) shape important economic, environmental and cultural values that are tied to closely defined geographic locations. To preserve wine products and wine-growing practices adopted in different PDOs these areas are strictly regulated by legal specifications. However, quality viticulture is increasingly under pressure from climate change, which is altering the local conditions of many winegrowing areas. Therefore, maintaining traditional wine products will require the adoption of tailored adaptation strategies, including possible changes in the legal regulation of protected wines. To this end, it is necessary to have a comprehensive knowledge on PDOs including their extension, products and allowed practices. While there have been efforts to build databases that summarize the characteristics for individual wine PDO areas and to quantify the related effects of climate change, much information is still included only in the official documentation of the EU geographical indication register and has never been collected in a comprehensive manner. With this study we aim at filling this gap by building a spatial inventory of European wine PDOs that supports decision making in viticulture in the context of climate change. To map and characterize European wine PDOs, we analysed their legal documents and extracted relevant information useful for climate change adaptation. The output consists of a comprehensive geographical dataset that identifies the boundaries of all 1200 European wine PDOs at unprecedented spatial resolution and includes a set of legally binding regulations, such as authorized vine varieties, maximum yields and planting density. The inventory will allow researchers to analyse the impacts of climate change on European wine PDOs and support decision makers in developing tailored adaptation strategies. This includes, among others, the evaluation of new vineyard site selection, the expansion of cultivated varieties or the authorization of irrigation in vineyards.

Is wine terroir a valid concept under a changing climate?

The OIV[i] defines terroir as a concept referring to an area in which collective knowledge of the interactions between the physical and biological environment (soil, topography, climate, landscape characteristics and biodiversity features) and vitivinicultural practices develops, providing distinctive wine characteristics. Those are perceptible in the taste of wine, which drives consumer preference and, therefore, wine’s value in the marketplace. Geographical indications (GI) are recognized regulatory constructs formalizing and protecting the nexus between wine taste and the terroir generating it. Despite considering updates, GIs do not consider the nexus as a dynamic one and do not anticipate change, namely of climate. Being climate a fundamental feature of terroir, it strongly impacts wine characteristics, such as taste. According to IPCC[ii], many widespread, rapid and unprecedented changes of climate occurred, some being irreversible over hundreds to thousands of years. Climatic shifts and atmospheric-driven extreme events have been widely reported worldwide. Recent climatic trends are projected to strengthen in upcoming decades, whereas extremes are expected to increase in frequency and intensity, forcing wines away from GI definitions. Geographical shifts of viticultural suitability are projected, often moving into regions and countries different from current ones. Some authors propose adaptation in viticulture, winemaking and product innovation. We show evidence of climate changing wine characteristics in the Douro valley, home of 270-year-old Port GI. We discuss herein resist or adapt stances for when climate changes the nexus between terroir and wine characteristics. Using the MED-GOLD[iii] dashboard, a tool allowing for easy visual navigation of past and future climates, we demonstrate how policymakers can identify future moments, throughout the 21st century under different emission scenarios, when GI specifications will likely need updates (e.g., boundaries, varieties) to reduce climate-change impacts.

austrianvineyards.com: online viewer of all designations of Austrian wine

To digitally record and present all the origins of Austrian wines in the same perfect and clear way was the motivation for the Austrian Wine Marketing Board (Austrian Wine) to start with the project in 2018. In June 2021 the results were presented to the public in an online viewer showing all the designations of Austrian wine, available at https://austrianvineyards.com in a largely barrier-free manner. The online viewer provides tailored individual maps fitted to the respective zoom level. The smallest unit of wine-origins in Austria is called Ried and is displayed in a plot-specific manner highlighting areas under vine. Information on the Ried include administrative district, winegrowing municipality, cadastral municipality, large collective vineyard site, specific winegrowing region, generic winegrowing region, winegrowing area and, in many cases, an illustrative picture. Complementary data on the size, elevation (minimum-maximum), orientation (in 8 sectors plus flat) and gradient (minimum, maximum, average) are based on the area under vine according to the EU’s Integrated Administration and Control System. Additional information covers climate data. The diagrams are taken from the monthly breakdown of data in the annals of the Central Institute for Meteorology and Geodynamics, Austria provide a display of values for air temperature, precipitation, and sunshine hours for the reference year and the long-term average. Seasonal aggregated data on temperature, precipitation, and sunshine hours complete the display. Short descriptions with emphasis on geology and soil, field name in historical maps, etymology of the denomination, and main planted variety complements the available information for the main designations in the online viewer. These descriptions are compiled by winegrowers, geologists, historians, and journalists. All the information and data can be extracted to a pdf-file. Printed vineyard maps are also available. Missing content regarding wine origins in Styria will be completed in winter 2021/22.

Climate modeling at local scale in the Waipara winegrowing region in the climate change context

In viticulture, a warming climate can have a very significant impact on grapevine development and therefore on the quality and characteristics of wines across different spatial scales, ranging from global to local. In order to adapt wine-growing to climate change, global climate models can be used to define future scenarios, but only at the scale of major wine regions. Despite the huge progress made over the last ten years in terms of the spatial resolution of climate models (now downscaled to a few square kilometres), they are not yet sufficiently precise to account for the local climate variability associated with such parameters as local topography, in spite of these parameters being decisive for vine and wine characteristics. This study describes a method to downscale future climate scenarios to vineyard scale. Networks of data loggers have been used to collect air temperature at canopy level in the Waipara winegrowing region (New Zealand) over five growing seasons. These measurements allow the creation of fine-scale geostatistical models and maps of temperature (at 100 m resolution) for the growing season. In order to model climate change at pilot site scale, these geostatistical models have been combined with regional climate change predictions for the periods 2031-2050 and 2081-2100 based on the RCP8.5 climate change scenario. The integration of local climate variability with regionalized climate change simulations allows assessment of the impacts of climate change at the vineyard scale. The improved knowledge gained using this methodology results from the increased horizontal resolution that better addresses the concerns of winegrowers. The results provide the local winegrowers with information necessary to understand current processes, as well as historical and future viticulture trends at the scale of their site, thereby facilitating decisions about future response strategies.