Search

Thanks to their low odor detection thresholds, free varietal thiols (VTs) play a key role in the primary aroma of wines, to which they confer an intense scent reminiscent of box tree, grapefruit, citrus fruits, passionfruit and cat urine odor. Excluding wines from a few VT-rich grapevine cultivars, VTs appear to be present in most cultivars at trace levels, although a comprehensive dataset is still missing. The low concentration of VTs combined with their high reactivity and matrix complexity make their determination in wines a challenging task. In this research an optimized liquid chromatography – tandem mass spectrometry (LC-MS/MS) method was validated and used for the quantification of 4-methyl-4-sulfanylpentan-2-one (4-MSP), 3-sulfanylhexan-1-ol (3-SH), 3-sulfanylhexyl acetate (3-SHA) and ethyl 3-sulfanylpropionate (E3SP) in 246 samples (vintage 2019) representative of 18 monovarietal Italian white wines. VTs were detected in all cultivars even though higher values of 3-SH were found in Lugana, Müller-Thurgau and Verdicchio cultivars. Müller-Thurgau wines showed the highest level of 4- MSP, that was mainly correlated to the odor descriptors of passionfruit and box tree/cat urine. The VTs composition of Müller-Thurgau was confirmed on a second set of 50 wines from different vintages. From a sensory perspective, the samples of Müller-Thurgau showed the best positive correlations between chemical variables and the odor descriptors thiol note, passion fruit and box tree/cat urine. These notes are significantly related to 4-MSP, suggesting that it could play a relevant olfactory role for the aroma of Müller-Thurgau wines. Sorting analysis allowed to group these wines according to their thiolic characteristics. The chemical variables and the odor descriptors attributable to the thiol notes are important for Müller-Thurgau and Lugana wines, while the contribution of thiol notes was sensorially negligible for the other wines.

Due to marketing recommendations, white wines are often bottled in flint glass to improve aesthetics and showcase wine color. Although this practice is known to cause a wine fault, the influence of light on the fruity and flowery aromatic profile of wine is unknown. The aim of this study was to investigate the changes to the white wine volatilome under typical supermarket shelf conditions, using 1,052 bottles of 24 white wines. After only 7 d of shelf life in flint glass bottles, a dramatic loss in terpenes (10 to 30%) and norisoprenoids (30 to 70%) was recorded, whereas colored glass bottles did not evidence such behavior even after 50 d, and darkness preserved the wine’s fruity and flowery aromatic integrity. We also proposed an alternative mechanism for the insurgence of the lightstrike off-odor, which takes the varietal aroma loss into account. In light of this understanding of the flint glass negative impact on white wine aroma identity and sensorial character, this packaging should be strongly discouraged. The same findings should be valid for a wide range of several daily consumed foodstuff where transparent packaging is used.

Aim. We aimed to study the impact of water deficit on the concentration of key flavour and phenolic secondary metabolites of wines.Methods and results. A drought-stress field trial was conducted on Vitis vinifera cv. Merlot and Tocai Friulano for two seasons. Fully irrigated (C) and deficit irrigated (D) grapes were microvinified and the resulting wines were analysed to determine the concentrations of anthocyanins, tannins, and free and glycosidically-bound Volatile Organic Compounds (VOCs). A descriptive sensory test was undertaken on the same wines. Water stressed grapes produced wines with higher concentrations of anthocyanins in Merlot and of free and glycosidically-bound monoterpenes in Tocai Friulano. Both cultivars displayed higher amounts of glycosidically-bound C13-norisoprenoids.Conclusions. Previously observed drought-induced compositional changes to the grapes were transfered to the wines, with an increase in polyphenols and VOCs. However, the timing and the duration of the water stress in the field only heavily impacted the final wine composition with major metabolic modification when the severe water deficit started early (at approximately 40 days after anthesis) and lasted over the entire season until harvest.Significance and impact of the study. This study highlights the positive role of a controlled water deficit on the composition of the wines in terms of secondary metabolites.

Knowing in detail how the white and red wine aroma compounds behave under various storage conditions and especially at high temperature is important in order to understand the changes occurring to their sensorial character during the shelf life. The initial aim of this work was to develop and validate a fast, modern, robust, and comprehensive protocol for the quantification of 64 primary, secondary, and tertiary volatile compounds by using solid-phase extraction (SPE) cartridges in sample preparation and fast GC-MS/MS (gas chromatography-tandem mass spectrometry assay) in analysis. The protocol was applied to a study of the behavior of seven Gewürztraminer and seven Teroldego wines stored in anoxia at 50 °C for 2.5 and 5 weeks. The results demonstrated a sharp decrease of the main linear terpenes linalool, geraniol, and nerol and the consequent increase of the cyclic ones, such as α-terpineol and 1,8-cineole; the increase of the C13-norisoprenoids 1,1,6,-trimethyl-1,2-dihydronapthalene (TDN), and β-damascenone and the C10 norisoprenoid safranal; the hydrolysis of acetates and linear esters; and the increase of some branched-chain esters. In red wines, a moderate increase was observed for some lactones. Some unwanted compounds, such as 2-aminoacetophenone (2-AAP), showed a notable increase in some Gewürztraminer wines, exceeding the olfactory threshold.

The influence of grape maturity on wine volatome was investigated using HS-SPME-GC × GC-TOFMS. Shiraz wines were made from grapes harvested from four different vineyards from two berry maturity levels. A total of 1276 putative compounds were detected in at least one of the wine samples and 175 showed significant trends related to grape maturity. The first two dimensions of the Principal component analysis accounted for 57% of the variation and separated the samples according to the harvest date. Wines from the first harvest date were characterised by an abundance of lipoxygenase derived compounds, norisoprenoids and sulfur-containing compounds whereas a significant increase in some acetate esters was observed in wines produced from the more mature grapes. This study demonstrated a common evolution of grape volatiles for Shiraz inside the same mesoclimate. During the late ripening stage of the grape, a direct nexus between sugar concentration and wine volatile evolution was not observed.

The spotted-wing drosophila (SWD), Drosophila suzukii Matsumura (Diptera: Drosophilidae), native to Eastern Asia, is an invasive alien species in Europe and the Americas, where it is a severe pest of horticultural crops, including soft fruits and wine grapes. The conventional approach to controlling infestations of SWD involves the use of insecticides, but the frequency of application for population management is undesirable. Consequently, alternative strategies are urgently needed. Effective and improved trapping is important as an early risk detection tool. This study aimed to improve Droskidrink&reg, (DD), a commercially available attractant for SWD. We focused on the chemical and behavioral effects of adding the bacterium Oenococcus oeni (Garvie) to DD and used a new trap design to enhance the effects of attractive lures. We demonstrate that microbial volatile compounds produced by O. oeni are responsible for the increase in the attractiveness of the bait and could be later utilized for the development of a better trapping system. Our results showed that the attractiveness of DD was increased up to two-fold by the addition of commercially available O. oeni when combined with an innovative trap design. The new trap-bait combination increased the number of male and especially female catches at low population densities.

Depending on the vineyard location, cluster thinning (CT) may represent an effective tool to obtain the desired grape composition and wine quality. The effect of 20% cluster thinning on Ribolla Gialla (Vitis vinifera L.) sparkling wine aroma, lipid compounds, and aromatic amino acid (AAA) metabolites composition was studied for three consecutive seasons in two vineyards located in the Friuli Venezia Giulia region, Italy. In the examined sparkling wines, the vintage meteorological conditions exhibited significant influences on the metabolic profile of the samples. Data were normalized by season, and the impact of the CT treatment was evaluated for each vineyard site separately. Crop removal showed a limited positive impact on aroma compounds in sparkling wines from vineyards located in the valley. Concerning the AAA compounds, their concentration was higher in the vineyard at the foot of the hills. Cluster thinning resulted in a drop in concentration, reducing the risk of atypical aging. Despite minor differences according to targeted metabolome profiling, the sensory analysis confirmed the effects of the CT treatment in the valley floor vineyard. Reducing crop in this site, where the yield was higher, promoted a moderate improvement of Ribolla Gialla sparkling wine. In contrast, for wine produced in the vineyard at the foot of the hills, the sensory analysis indicated a preference for wines from the unthinned control samples. Overall, the study indicates that cluster thinning is a viticultural technique that could potentially improve the quality of Ribolla Gialla sparkling wines, but only in situations of excessive grape production.

White wines from two vintages were bottled in green and flint glass bottles and stored under typical supermarket shelf conditions. Light-strike fault, colour changes, light and temperature exposure were monitored up to 50 days. In general, green glass bottles secured wine quality for the tested period. Only a few flint glass bottled wines developed a fault due to light-strike after 1–2 days of supermarket shelf life, but all developed the fault after 20–40 days; so we considered the possibility of two mechanisms causing the problem. Flint-glass bottled wines stored on the bottom shelf developed the defect only slightly later compared with the wines on the top shelf. Moreover, storing the wines in dark and cold after a period of exposure to light did not eliminate the fault, indicating that the defect is probably additive. Monitoring the amount of light to which wines are exposed could prevent the fault.

Introduction Aromas and tastes have crucial influences on the quality of fermented beverages. The determination of aromatic compounds requires global non-targeted profiling of the volatile organic compounds (VOCs) in the beverages. However, experimental VOC profiling result depends on the chosen VOC collection method. Objectives This study aims to observe the impact of using different sample preparation techniques [dynamic headspace (DHS), vortex-assisted liquid–liquid microextraction (VALLME), multiple stir bar sorptive extraction (mSBSE), solid phase extraction (SPE), and solid phase micro-extraction (SPME)] to figure out the most suitable sample preparation protocol for profiling the VOCs from fermented beverages. Methods Five common sample preparation methods were studied with beer, cider, red wine, and white wine samples. After the sample preparation, collected VOCs were analyzed by two-dimensional gas chromatography coupled with time of flight mass spectrometry (GCxGC-TOFMS). Results GCxGC oven parameters can be optimized with the Box–Behnken surface response model and response measure on peak dispersion. Due to the unavoidable column and detector saturation during metabolomic analysis, errors may happen during mass spectrum construction. Profiling results obtained with different sample preparation methods show considerable variance. Common findings occupy a small fraction of total annotated VOCs. For known fermentative aromas, best coverage can be reached by using SPME together with SPE for beer, and VALLME for wine and cider. Conclusions GCxGC-TOFMS is a promising tool for non-targeted profiling on VOCs from fermented beverages. However, a proper data processing protocol is lacking for metabolomic analysis. Each sample preparation method has a specific profiling spectrum on VOC profiling. The coverage of the VOC metabolome can be improved by combining complementary methods.

Background and Aims This study evaluated the impact that the non-Saccharomyces yeasts, Torulaspora delbrueckii (TD), Lachancea thermotolerans (LT), Pichia kluyveri (PK), Metschnikowia pulcherrima (MP), Candida zemplinina (CZ) and Kazachstania aerobia (KA), in sequential inoculation with Saccharomyces cerevisiae (SC), had on the volatile chemical profile of Shiraz wine. Methods and Results Shiraz grape must was inoculated with monocultures of the non-Saccharomyces yeasts, which were allowed to ferment until 2% v/v ethanol concentration was reached at which point, SC was added to complete the alcoholic fermentation. The control was SC in monoculture. The final wines were subjected to solid phase microextraction-GC × GC-time of flight-MS to evaluate the untargeted volatile metabolite profile of each treatment. Each fermentation produced a unique chemical profile. The LT–SC sequential fermentation was the most significantly different from the control primarily in the ester, alcohol and terpene profile. The KA–SC sequential fermentation had the highest amount of volatile acidity, and the PK–SC sequential fermentation had a relatively high amount of acetaldehyde and a few esters. The MP–SC sequential fermentation also revealed a higher concentration of several esters. The TD–SC sequential fermentation was notable for its lack of a distinct pattern in comparison with that of the other fermentations. Conclusions Given these characteristics, the LT–SC sequential fermentation showed the most potential for increased chemical complexity of the Shiraz volatile profile. Significance of the Study The results demonstrate that there is no clear, singular trend for how different, non-Saccharomyces species of yeast – once thought to be wholly unfavourable in wine fermentations – will impact wine chemistry, flavour or quality. Each species presents unique metabolic characteristics, many of which could be beneficial, and their potential application in the wine industry should be considered.

Shiraz wine volatomes from two Australian geographical indications (GIs), that is, Orange and Riverina, were compared using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry. Shiraz wines were made in triplicate from grapes harvested at two harvest dates from six vineyards in the two GIs. A total of 133 compounds showed a significant trend between wines from the cooler Orange GI and warmer Riverina. Compounds associated with wines from the cooler climate were grape-derived volatiles, such as monoterpenes, sesquiterpenes, green leaf volatiles, and some norisoprenoids. Fermentation-derived compounds, such as esters and S-containing compounds, showed no specific trend related to grape origin. In addition, wines could be also clearly separated according to the harvest date, irrespective of the climate, with C6 compounds, higher alcohol acetates, and other esters contributing utmost to the differentiation of samples, whereas terpenoids and norisoprenoids did not have an influence. This study demonstrated the plasticity of wine volatome related to grape origin and also the maturity level (harvest date), irrespective of climate.

Every grape cultivar has its own unique genetic characteristics, leading to the production of a different secondary metabolite profile. Aroma is one of the most important aspects in terms of the quality of grapes and previous studies have assigned specific aromas to particular grape cultivars. In this study we present the molecular profiling of volatile aroma metabolites and their precursors in ten selected genotypes, including six Vitis vinifera cultivars, two American species (Arizonica Texas, Vitis cinerea) and two interspecific crosses. Chemical profiling was achieved through combined use of two orthogonal techniques, GC-MS and LC-HRMS, before and after enzymatic hydrolysis. The results show that both free and glycosidically bound aroma precursors behave differently in each different grape cultivar and species. As many as 66 free aroma volatile molecules (originally existing and released after hydrolysis) were profiled through GC-MS analysis, while 15 glycosylated precursors of volatiles were identified through LC-HRMS and correlation with GC-MS data.

Saccharomyces cerevisiae is the main driver of alcoholic fermentation. It is typically inoculated at high levels to ensure successful implantation as well as reduce the risks of stuck fermentations and off-flavor production. However, winemakers have found that wines produced with only S. cerevisiae can be lacking in complexity compared to fermentations where non-Saccharomyces yeasts are more active. This study sought to understand the early fermentation characteristics of Kazachstania gamospora, Lachancea thermotolerans, Metschnikowia pulcherrima, Torulaspora delbrueckii and Zygosaccharomyces kombuchaensis in both Sauvignon blanc and Syrah musts. S. cerevisiae was used as a control. Solid-phase microextraction coupled to GC–MS was used to evaluate the musts once they reached 2% ethanol concentration. The method targeted 90 different compounds known to occur in wine and/or be produced by yeast during fermentation. For the first time, K. gamospora and Z. kombuchaensis have been studied in the context of wine. While the other yeasts are commercially available starter cultures, they have never been profiled this extensively. Analysis showed that each yeast profile was unique and different based on the must. The non-Saccharomyces yeasts produced lower concentrations of esters, alcohols and terpenes with the exception of K. gamospora which produced more total esters than the control.

The composition and changes of the fungal population and of the metabolites present in grapes and in ferments of Vitis vinifera L. cv. Corvina, one of the major components of the Amarone musts, were dissected aiming at the identification of constant characteristics possibly influenced by the productive process. The fungal populations and metabolomic profiles were analyzed in three different vintages. 454-pyrosequencing on the ribosomal ITS1 region has been used to identify the fungal population present in Corvina grapes and fresh must. Samples were also subjected to metabolomics analysis measuring both free volatile compounds and glycosylated aroma precursors through an untargeted approach with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. Albeit strongly dependent on the climate, both the mycobiota and metabolome of Corvina grapes and fresh musts show some characteristics recursive in different vintages. Such persistent characteristics are likely determined by the method adopted to produce Amarone or other dry wines made from partially dried grapes. In particular, the harsh conditions imposed by the prolonged withering appear to contribute to the shaping of the fungal populations. The fungal genera and metabolites present in different vintages in V. vinifera L. cv. Corvina grapes and fresh musts represent core components of the peculiar technique of production of Amarone. Their identification allows the in-depth understanding and improved control of the process of production of this economically and culturally relevant wine.\ud \ud

Glycosides are ubiquitous plant secondary metabolites consisting of a non-sugar component called an aglycone, attached to one or more sugars. One of the most interesting aglycones in grapes and wine is methyl salicylate (MeSA), an organic ester naturally produced by many plants, particularly wintergreens. To date, nine different MeSA glycosides from plants have been reported, mainly spread over the genera Gaultheria, Camellia, Polygala, Filipendula, and Passiflora. From a sensorial point of view, MeSA has a balsamic-sweet odor, known as Wintergreen. MeSA was found in Vitis riparia grapes, in Vitis vinifera sp. and in the Frontenac interspecific hybrid. We found that the MeSA glycosides content in Verdicchio wines and in some genetically related varieties (Trebbiano di Soave and Trebbiano di Lugana) was very high. In order to understand which glycosides were present in wine, the methanolic extract of Verdicchio wine was injected into a UPLC-Q-TOF-HDMS and compared to the extracts of different plants rich in such glycosides. Using pure standards, we confirmed the existence of two glycosides in wine: MeSA 2-O--d-glucoside and MeSA 2-O--d-xylopyranosyl (1-6) -d-glucopyranoside (gaultherin). For the first time, we also tentatively identified other diglycosides in wine: MeSA 2-O--l-arabinopyranosyl (1-6)--d-glucopyranoside (violutoside) and MeSA 2-O--d-apiofuranosyl (1-6)--d-glucopyranoside (canthoside A), MeSA 2-O--d-glucopyranosyl (1-6)-O--d-glucopyranoside (gentiobioside) and MeSA 2-O--l-rhamnopyranosyl (1-6)--d-glucopyranoside (rutinoside). Some of these glycosides have been isolated from Gaultheria procumbens leaves by preparative liquid chromatography and structurally annotated by 1H- and 13C-NMR analysis. Two of the peaks isolated from Gaultheria procumbens leaves, namely MeSA sambubioside and MeSA sophoroside, were herein observed for the first time. Six MeSA glycosides were quantified in 64 Italian white wines, highlighting the peculiar content and pattern in Verdicchio wines and related cultivars. The total concentration in bound and free MeSA in Verdicchio wines varied in the range of 456&ndash, 9796 g/L and 5.5&ndash, 143 g/L, respectively, while in the other wines the bound and free MeSA was below 363 g/L and 12 g/L, respectively. As this compound&rsquo, s olfactory threshold is between 50 and 100 g/L, our data support the hypothesis that methyl salicylate can contribute to the balsamic scent, especially in old Verdicchio wines.

Saccharomyces cerevisiae (SC) is the main driver of alcoholic fermentation, however for aroma and flavor formation in wine, non-Saccharomyces species can have a powerful effect. This study aimed to compare untargeted volatile compound profiles from SPME–GCxGC-TOF-MS and sensory analysis data of Sauvignon blanc wine inoculated with six different non-Saccharomyces yeasts followed by SC. Torulaspora delbrueckii (TD), Lachancea thermotolerans (LT), Pichia kluyveri (PK) and Metschnikowia pulcherrima (MP) where commercial starter strains, while Candida zemplinina (CZ) and Kazachstania aerobia (KA), were isolated from wine grape environments. Each wine showed a distinct profile both sensorially and chemically. SC and CZ wines were the most distinct in both of these cases. SC wine had guava, grapefruit, banana, and pineapple aromas while CZ wine was driven by fermented apple, dried peach/apricot, and stewed fruit as well as sour flavor. Chemically over 300 unique features were identified as significantly different across the fermentations. SC wine had the highest number of esters in the highest relative concentration but all the yeasts had distinct ester profiles. CZ wine displayed the highest number of terpenes in high concentration but also produced a large amount of acetic acid. KA wine was high in ethyl acetate. TD wine had fewer esters but three distinctly higher thiol compounds. LT wine showed a relatively high number of increased acetate esters and certain terpenes. PK wine had some off odor compounds while the MP wine had high levels of methyl butyl-, methyl propyl-, and phenethyl esters. Overall, this study gives a more detailed profile of these yeasts contribution to Sauvignon blanc wine than previously reported.

Biosynthesis of the sesquiterpene rotundone in Vespolina grapes during berry ripening was investigated over two consecutive seasons, revealing that the compound accumulates from veraison to harvest and reaches relatively high concentrations (up to 5.44 μg/kg). Rotundone levels up to 1.91 μg/kg were also found in clones of Gruener Veltliner, a white grape variety known to give 'peppery' wines. These concentrations are higher than those reported for Syrah grapes and are similar to the levels found in some plants. Rotundone was shown to accumulate almost exclusively in berry exocarp, suggesting that skin contact during winemaking could be used to modulate the peppery character of red wine. However, rotundone yield after the winemaking process was relatively low. Indeed, only 10% of the rotundone present in grapes was extracted during fermentation, and only 6% was recovered in bottled wine. The results presented in this work provide key knowledge for manipulation of the peppery character of wine in order to optimize the intensity of this characteristic wine aroma.

Rotundone is an oxygenated sesquiterpene belonging to the family of guaianes, giving the ‘peppery’ aroma to white and black pepper and to red wines. Here we describe a novel, convenient protocol for the synthesis of rotundone, starting from a commercially available compound and requiring only two reaction steps, and an improved, faster method of GC separation (30 min) with selective quantisation of rotundone using tandem mass spectrometry in multiple reaction monitoring (MRM) mode with d5-rotundone as internal standard. With limits of detection (LODs) of 1.5 ng/L in white wine and 2.0 ng/L in red wine, intraday repeatability CV values of 6% and 5% at 50 ng/L and 500 ng/L and interday repeatability CV values of 13% and 6% at 50 ng/L and 500 ng/L, respectively, the improved protocol provides the desired sensitivity and selectivity for routine analysis of rotundone in both white and red wines. Initial application of this method highlighted the presence of unexpectedly high concentrations of rotundone, thus explaining the origin of the distinctive peppery aroma in Schioppettino and Vespolina red wines and in Gruener Veltliner white wines. Copyright © 2011 John Wiley & Sons, Ltd.

We carried out comprehensive mapping of volatile compounds in 70 wines, from 48 wineries and 6 vintages, representative of the two main production areas for Italian sparkling wines, by HS-SPME-GCxGC-TOF-MS and multivariate analysis. The final scope was to describe the metabolomics space of these wines, and to verify whether the grape cultivar signature, the pedoclimatic influence of the production area, and the complex technology were measurable in the final product. The wine chromatograms provided a wealth of information, with 1695 compounds being found. A large number of putative markers influenced by the cultivation area was observed. A subset of 196 biomarkers fully discriminated between the two types of sparkling wines investigated. Among the new compounds, safranal and α-isophorone were observed. We showed how correlation-based network analysis could be used as a tool to detect the differences in compound behaviour based on external/environmental influences.