IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 An Ag+ SPE method combined with Deans’ switch heart-cutting MDGC–MS/Olfactometry approach for identifying unknown volatile thiols in wine

An Ag+ SPE method combined with Deans’ switch heart-cutting MDGC–MS/Olfactometry approach for identifying unknown volatile thiols in wine

Abstract

Wine aroma is a crucial quality criterion. A multitude of volatile compounds have been identified and correlated to the aroma attributes perceived in wine. Volatile thiols are a category of volatile sulfur compounds that are well-recognized as potent aroma-impacting odorants contributing to various aroma attributes of many wines because of their low odor detection thresholds (ng/L). However, volatile thiols are highly reactive and generally present at ultra-trace concentrations (ng/L) in wines, causing major analytical difficulties. For more than two decades, the identifications of new volatile thiols were nearly exclusively achieved by the use of organomercuric compounds for thiol extraction, followed by conventional gas chromatography and mass spectrometry/olfactometry (GC–MS/O) for chromatographic separation, odorous zone profiling, and MS detection. However, such analytical protocols required the use of highly toxic organomercuric chemicals and are often laborious. Meanwhile, olfactometry data of other unknown thiol odorous zones has been reported but their identities were not pursued.
This work focused on the aroma of premium red wines and aimed to identify unknown volatile thiols. First, we developed a silver ion solid-phase extraction (Ag+ SPE) method for thiol isolation. Ag+ SPE cartridge selectivity, cartridge wettability, reservoir material, and elution reagent were evaluated. The developed Ag+ SPE method was safe, simple, scalable, selective, and artefact resistant, suitable for qualitative identification tasks. Low thermal mass (LTM) Deans’ switch (DS) heart-cutting multidimensional GC–MS/O (H/C MDGC–MS/O) was optimized for its performance using three model volatile thiol analytes. Significant impacts of instrument parameters including main host oven temperature, H/C width, and cryogenic trapping on the separation and detection were observed. Main host oven at high temperature was required to maintain flow balance for H/C operation. Narrow H/C width was selected to avoid irregular chromatographic behavior. Cryogenic trapping at the optimal temperature was needed to effectively capture the H/C effluent at the inlet of second column and to significantly enhance peak detection. The development of the Ag+ SPE H/C MDGC–MS/O protocol was applied to screen a selection of several premium Bordeaux red wines presenting a bouquet with intense empyreumatic nuances. In selected wines, a number of odorous zones with such aroma descriptors were characterized. Supported by olfactometric results, retention data, and corresponding mass spectra, the identification of odorous thiols that were not previously reported in wine was described. The identification of unknown thiols expands our understanding of the volatile molecular markers contributing to the aroma quality of premium wines

DOI:

Publication date: June 22, 2022

Issue: IVAS 2022

Type: Article

Authors

Chen Liang¹* and Darriet Philippe¹

¹Univ. Bordeaux, INRAE, Bordeaux INP, UMR1366 Œnologie, ISVV, F-33140 Villenave d’Ornon, France

Contact the author

Keywords

red wine, aroma, volatile thiols, extraction, identification

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Applications of FTIR microspectroscopy in oenology: shedding light on Saccharomyces cerevisiae cell wall composition and autolytic capacity

Many microbial starters for the alcoholic and malolactic fermentation processes are commercially available, indicated for diverse wine styles and quality goals. The screening protocols cover a wide range of oenologically relevant features, although some characteristics could also be studied using underexplored powerful techniques. In this study, we applied Fourier Transform Infrared (FTIR) microspectroscopy [1,2] to compare the cell wall biochemical composition and monitor the autolytic process in several wine strains of Saccharomyces cerevisiae.

Read More

In vitro regeneration of grapevine cv. Aglianico via somatic embryogenesis: preliminary studies for next genome editing applications  

Italy is a rich hub of viticultural biodiversity harboring hundreds of indigenous grape varieties that have adapted over centuries to the diverse climatic and geographic conditions of its regions. Preserving this biodiversity is essential for maintaining a diversified genetic pool, crucial for addressing future challenges such as climate change and emerging plant diseases. Rising temperatures, precipitation pattern variations, and extreme weather events can affect grape ripening, crop quality, and contribute to disease development. Integrated disease management necessitates exploration of novel strategies. Biotechnologies emerge as a significant player in tackling modern viticulture challenges.

Read More

Contribution to the sensory and volatile characterization of four traditional Galician red varieties

Galicia, a region sited in the northwest of Spain, is one of the most important wine production area, with five Appellations of Origin Controlled (AOC).

Read More

Territorial delimitation of viticultural “Oltrepo Pavese (Lombardy)” using grape ripening precocity

L’Oltrepò Pavese est une zone de collines de la Lombardie, région située au nord de l’Italie avec un vignoble qui s’étend sur près de 15 000 ha. Cette zone représente la plus grande aire de production de la région et une des A.O.C. les plus étendues de tout le pays. Les cépages les plus cultivés, même historiquement, sont autochtones : la Barbera et la Croatina utilisés pour la production de vin rouge «Oltrepò» et le Pinot noir pour la production de vins mousseux. Pour le zonage viticole de cette A.O.C., il a été pris en considération: le climat, les sols, les caractéristiques viti-vinicoles.

Read More

20-Year-Old data set: scion x rootstock x climate, relationships. Effects on phenology and sugar dynamics

Global warming is one of the biggest environmental, social, and economic threats. In the Douro Valley, change to the climate are expected in the coming years, namely an increase in average temperature and a decrease in annual precipitation. Since vine cultivation is extremely vulnerable and influenced by the climate, these changes are likely to have negative effects on the production and quality of wine.
Adaptation is a major challenge facing the viticulture sector where the choice of plant material plays an important role, particularly the rootstock as it is a driver for adaptation with a wide range of effects, the most important being phylloxera, nematode and salt, tolerance to drought and a complex set of interactions in the grafted plant.
In an experimental vineyard, established in the Douro Region in 1997, with four randomized blocs, with five varieties, Touriga Nacional, Tinta Barroca, Touriga Franca and Tinta Roriz, grafted in four rootstocks, Rupestris du Lot, R110, 196-17C, R99 and 1103P, data was collected consecutively over 20 years (2001-2020). Phenological observations were made two to three times a week, following established criteria, to determine the average dates of budbreak, flowering and veraison. During maturation, weekly berry samples were taken to study the dynamics of sugar accumulation, amongst other parameters. Climate data was collected from a weather station located near the vineyard parcel, with data classified through several climatic indices.
The results achieved show a very low coefficient of variations in the average date of the phenophases and an important contribution from the rootstock in the dynamic of the phenology, allowing a delay in the cycle of up to10-12 days for the different combinations. The Principal Component Analysis performed, evaluating trends in the physical-chemical parameters, highlighted the effect of the climate and rootstock on fruit quality by grape varieties.

Read More