IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Exploring and unravelling the complex toasted oak wood (Q. sp.) volatilome using GCxGC-TOFMS technique

Exploring and unravelling the complex toasted oak wood (Q. sp.) volatilome using GCxGC-TOFMS technique

Abstract

For coopers, toasting process is considered as a crucial step in barrel production where oak wood develops several specific aromatic nuances released to the wine during its maturation. Toasting is applying varying degrees of heat to a barrel over a specific amount of time. Today it is well known that as the temperature increases, thermal degradation of oak wood structure produces a huge range of chemical compounds. Indeed, many works were conducted to identify key aroma volatile compounds (e.g., whisky-lactone, furfural, maltol, eugenol, guaiacol, vanillin) using the traditional gas chromatography coupled with olfactometry and mass spectrometry (GC-O-MS).

Inspired by recent untargeted approaches in food “omics”, this work aims at expanding our knowledge on oak wood volatile composition by bi-dimensional comprehensive gas chromatography-time of flight mass spectrometry (GCxGC-TOFMS, BT4D, Leco).

In a first experiment, five toasting levels were selected and applied to Q. sessilis oak wood samples (control, 160 °C, 180 °C, 200 °C and 220 °C, 30 min, n=3). Organic extracts were prepared (dichloromethane, 50 g/L) and analysed by GCxGC-TOFMS on conventional column combination nonpolar/midpolar (DB-5ms/Rxi-17Sil). The separation was followed by a non-targeted approach for data processing. The resulting mass spectra (TIC) were de convoluted (ChromaTOF software) and compared to spectra from a database for tentative peak identification. It was necessary to restrict the number of processed peaks by applying some “filters” such as signal to noise (S/N > 50), linear retention index (LRI ± 30), mass spectra similarity (> 750) and repeatability level. Supervised multivariate and univariate statistical approaches were used to identify potential markers of toasting intensity. Thanks to R script, reproducible peaks number was reduced from about 15000 to 568. By comparing observed retention indices with those found in the literature, 77 of the identifications have been confirmed and associated with an increase in toasting intensity. Some of them were sensory active and well known in oak wood, such as guaiacol, creosol and isoeugenol. Others were identified for the first time in toasted oak wood such as 2-methylbenzofurane (burnt) and 2-hydroxy-2-cyclopenten-1-one (caramel).Additional results were also discussed on the capability of GCxGC-TOFMS to identify oak wood botanic origins (Q. robur, Q. alba

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Courregelongue Marie1,², Albertin Warren1,³, Prida Andrei2 and Pons Alexandre1,²

¹UMR ŒNOLOGIE (OENO), ISVV, UMR 1366, Université de Bordeaux, INRAE, Bordeaux INP
²Tonnellerie Seguin Moreau, Merpins, France
³ENSCBP, Bordeaux INP, 33600, Pessac, France

Contact the author

Keywords

non-targeted analysis, GCxGC-TOFMS, oak wood, toasting process, volatile compounds

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

The modification of cultural practices in grapevine cv. Syrah, does it modify the characteristics of the musts?

The work shows the results of a year of experimentation (2020) in a Syrah variety vineyard in La Roda (Castilla-La Mancha, Spain). The trial approach was on a randomized block design with two factors: Irrigation (I) and Pruning (P).
Irrigation schedules were adjusted to apply amounts close to 1,500 m3/ha. With this provision, 2 different irrigation treatments were proposed: I1) Start of irrigation from pea-sized grape to post-harvest (providing at least 20 % of the total amount of irrigation water to be provided post-harvest); I2) Start of irrigation from pea-sized grape to harvest (usual irrigation practice in the study area). Pruning was proposed with two treatments, one at the end of January (P1), which is pruning on a conventional date; and P2) pruning carried out at the beginning of budding. In total, 4 repetitions were designed with 4 elementary plots, each one of them representing one of the proposed treatments (I1P1; I1P2; I2P1; I2P2). In total, 16 plots were worked on and each elementary plot consisted of 30 strains, distributed in 3 lines.
The productive response was evaluated with the yield results of the harvest harvested at 23 ºBrix. The qualitative response was measured in the musts through the indices of technological (acidity, pH and potassium) and phenolic maturity and aromatic compounds in free and glycosylated fractions. The treatments tested had, in general, an effect on the different variables analyzed.

Analysis of Cabernet Sauvignon and Aglianico winegrape (V. vinifera L.) responses to different pedo-climatic environments in southern Italy

Water deficit is one of the most important effects of climate change able to affect agricultural sectors. In general, it determines a reduction in biomass production, and for some plants, as in the case of grapevine, it can endorse fruit quality. The monitoring and management of plant water stress in the vineyard

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.

Genotypic variability in root architectural traits and putative implications for water uptake in grafted grapevine

Root system architecture (RSA) is important for soil exploration and edaphic resources acquisition by the plant, and thus contributes largely to its productivity and adaptation to environmental stresses, particularly soil water deficit. In grafted grapevine, while the degree of drought tolerance induced by the rootstock has been well documented in the vineyard, information about the underlying physiological processes, particularly at the root level, is scarce, due to the inherent difficulties in observing large root systems in situ. The objectives of this study were to determine genetic differences in the root architectural traits and their relationships to water uptake in two Vitis rootstocks genotypes (RGM, 140Ru) differing in their adaptation to drought. Young rootstocks grafted upon the Riesling variety were transplanted into cylindrical tubes and in 2D rhizotrons under two conditions, well watered and moderate water stress. Root traits were analyzed by digital imaging and the amount of transpired water was measured gravimetrically twice a week. Root phenotyping after 30 days reveal substantial variation in RSA traits between genotypes despite similar total root mass; the drought-tolerant 140Ru showed higher root length density in the deep layer, while the drought-sensitive RGM was characterised by shallow-angled root system development with more basal roots and a larger proportion of fine roots in the upper half of the tube. Water deficit affected canopy size and shoot mass to a greater extent than root development and architectural-related traits for both 140Ru and RGM, suggesting vertical distribution of roots was controlled by genotype rather than plasticity to soil water regime. The deeper root system of 140Ru as compared to RGM correlated with greater daily water uptake and sustained stomata opening under water-limited conditions but had little effect on above-ground growth. Our results highlight that grapevine rootstocks have constitutively distinct RSA phenotypes and that, in the context of climate change, those that develop an extensive root network at depth may provide a desirable advantage to the plant in coping with reduced water resources.

Organic recycled mulches in sustainable viticulture: assessment of spontaneous plants communities and weed coverage

In recent years, developing more efficient and sustainable viticulture management has been essential due to the impact of climate change in semiarid regions. For this reason, the use of recycled organic mulching (ROM) in the vineyard has become an interesting strategy to cope with water stress, isolated soil from extreme temperatures and improving soil humidity, control the presence of weeds and therefore reduce the inputs of herbicides and improve soil fertility. This work aimed to analyse the effect of three different organic mulches [straw (S), grape pruning debris (GPD) and spent mushroom compost (SMC)] and two traditional soil management techniques [herbicide (H) and interrow (IN)] on weed coverage and the spontaneous plant communities’ presence. Data sampling was collected throughout the vine vegetative cycle of 2021 in La Rioja, Spain. The different soil management techniques had a clear effect on weed coverage and his development during the vine vegetative cycle. SMC and H were the treatments with the highest and the lowest coverage percentage, respectively. IN had a delayed weed emergence at the beginning of the vine vegetative cycle, but finally it reached maximum values nearby SMC. GPD and S had similar effects on weed emergence, reaching 25-30% of the maximum coverage values. A total of 29 herbaceous species were identified during the vegetative cycle, some of them very isolated and occasional. Principal component analysis (PCAs) showed a good association between spontaneous species and treatments, furthermore, specific species-treatment associations were found. Moreover, three clear groups of herbaceous communities were identified by cluster analysis. This study provides interesting information about the effect of different alternative soil management on herbaceous plant coverage and weed species communities which could contribute to making more sustainable viticulture.