Time In Wines Research Articles

Distribution and Sensory Impact of (2E,4E,6Z)-nonatrienal and Trans-4,5-epoxy-(E)-2-decenal in Wines and Spirits.

This study reports the distribution of (2E,4E,6Z)-nonatrienal (1) and trans-4,5-epoxy-(E)-2-decenal (2) in wines and spirits. We validated a quantification method using solid-phase extraction (SPE) and negative chemical ionization (NCI, NH3) gas chromatography-mass spectrometry (GC-MS) analysis. Both were identified for the first time in wines and spirits from different grape varieties and raw materials. Their olfactory detection thresholds (ODTs) were 16 and 60 ng/L, respectively. Analysis of 66 wines showed that the highest levels of (1) (441.3 ng/L) and (2) (386.5 ng/L) were found in red and white wines, respectively. At these levels, they modify the balance of the fruity expression of red (fresh to cooked fruits) and white (vegetal/green hazelnut nuance) wines. Similar quantitative and sensory analyses were conducted in spirits. With ODT estimated at 500 and 400 ng/L and concentrations ranging from trace amounts to 1.1 and 2.4 μg/L respectively, (1) and (2) can contribute directly to the aroma of spirits.

Understanding sweetness of dry wines: First evidence of astilbin isomers in red wines and quantitation in a one-century range of vintages

Astilbin (2R, 3R) was recently reported to contribute to wine sweetness. As its aglycon contains two stereogenic centers, three other stereoisomers may be present: neoisoastilbin (2S, 3R), isoastilbin (2R, 3S), and neoastilbin (2S, 3S). This work aimed at assaying their presence for the first time in wines as well as their taste properties. The isomers were synthesized from astilbin and purified by semi-preparative HPLC. With the four stereoisomers, a sweet taste was perceived whose intensity varied with the configuration. Their content was assayed by developing a UHPLC-Q-Exactive method. The method was applied to screen astilbin and isomers in various wines, especially in different vintages from the same estate. While young wines contained higher concentrations of astilbin than the old ones, the concentrations of the other isomers, mainly neoastilbin, were higher in the old wines, suggesting their formation over time.

Dual solid-phase and stir bar sorptive extraction combined with gas chromatography-mass spectrometry analysis provides a suitable tool for assaying limonene-derived mint aroma compounds in red wine

A novel analytical method was developed for quantitative determination of eight limonene-derived monoterpenes responsible for the mint aroma in red wine. As these aromatic compounds are present at trace levels, a new dual extraction approach was proposed, combining solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE), followed by gas chromatography-mass spectrometry analysis. The various parameters affecting the efficiency of extracting the analytes from wine samples in both the SPE and SBSE steps were first investigated, to determine the best compromise for the simultaneous analysis of the compounds studied. Following preliminary optimization of the dilution factor, phase ratio, and methanol content in the SBSE sample, cartridge sorbent mass, type of solvent, elution volume, and wine sample volume in the pre-concentration SPE step were studied. Highest response values were obtained when a 90 mL wine sample was extracted on a 500 mg SPE C18 cartridge and eluted with 1.5 mL methanol. The wine extract was then diluted in 10 mL water to obtain a final methanol content of 15% before the SBSE step. Good linearity, repeatability, reproducibility, accuracy and the required low detection and quantification limits were obtained under the conditions described, making this SPE-SBSE combination a suitable, powerful tool for routine analysis of the selected limonene-derived mint aroma compounds in large series of wine samples. Finally, the validated method was applied to 15 commercial red Bordeaux wines, aged from 3 to 23 years. Most of the compounds studied, present within the ng.L−1 range, were easily quantified for the first time in wine.

HPLC-DAD–MS/MS characterization of phenolic compounds in white wine stored without added sulfite

The oxidation of dihydroxybenzene and hydroxycinnamate compounds generates unstable quinones which undergo further reactions to combine nucleophilic compounds. These reactions are limited when sulfur dioxide (SO2) is used as wine preservative, as SO2 plays an important role in reducing quinones back to their phenol form. In no sulfite-added wine, oxidation chemistry undoubtedly results changed. Therefore, in this work, the phenolic profile of a white wine without adding sulfites, after twelve-month storage, was investigated by HPLC-DAD-MS/MS and compared to a control stored with sulfur dioxide. A total of twenty-six phenolics were detected including hydroxycinnamate derivatives and minor compounds resulting from oxidation processes, i.e. oxidized caffeic acid dimers, whose structures were tentatively proposed on the basis of their UV, MS, and MS/MS typical fragmentation. The experimental evidence of these latter is described for the first time in wine stored without added sulfites, and it may contribute to get new insight in the field of wine oxidation processes.

Evaluation of microbial diversity in sulfite-added and sulfite-free wine by culture-dependent and -independent methods

The difference in microbiota including non-lactic acid bacteria, non-acetic acid bacteria, and wild yeast during winemaking and in the end-products between sulfite-added and sulfite-free wine, was investigated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and a culture-dependent method. There were differences between the microorganisms detected by PCR-DGGE and those detected by the culture-dependent method, probably because of the selectivity of culture medium and the characteristics of PCR-based method. In both the red wine and white wine, the microbial diversity of the sulfite-added wine was lower than that of the sulfite-free wine during fermentation. Tatumella terrea was detected from the fermenting must by PCR-DGGE and by the culture-dependent method, even though sulfite inhibited its growth to some extent. We confirmed that the addition of sulfite plays an important role in winemaking by inhibiting the growth of unexpected microorganisms, but on the other hand, it was revealed that some microorganisms can survive and grow in sulfite-added fermenting must. We also analyzed 15 samples of commercial wines by the PCR-DGGE method and detected various microorganisms. Among them, Sphingomonas sp., Pseudozyma sp., Ochromonas sp. and Methylophilus sp. were found for the first time in wine as far as we know. We did not identify a specific microorganism that was detected only from wines without sulfite addition. Thus, the microbiota of end-products seemed to be influenced by other factors, such as filtration before bottling, the production equipment and the storage environment.

Alcoholic fermentation induces melatonin synthesis in orange juice

Melatonin (N-acetyl-5-methoxytryptamine) is a molecule implicated in multiple biological functions. Its level decreases with age, and the intake of foods rich in melatonin has been considered an exogenous source of this important agent. Orange is a natural source of melatonin. Melatonin synthesis occurs during alcoholic fermentation of grapes, malt and pomegranate. The amino acid tryptophan is the precursor of all 5-methoxytryptamines. Indeed, melatonin appears in a shorter time in wines when tryptophan is added before fermentation. The aim of the study was to measure melatonin content during alcoholic fermentation of orange juice and to evaluate the role of the precursor tryptophan. Identification and quantification of melatonin during the alcoholic fermentation of orange juice was carried out by UHPLC-QqQ-MS/MS. Melatonin significantly increased throughout fermentation from day 0 (3.15 ng/mL) until day 15 (21.80 ng/mL) reaching larger amounts with respect to other foods. Melatonin isomer was also analysed, but its content remained stable ranging from 11.59 to 14.18 ng/mL. The enhancement of melatonin occurred mainly in the soluble fraction. Tryptophan levels significantly dropped from 13.80 mg/L (day 0) up to 3.19 mg/L (day 15) during fermentation. Melatonin was inversely and significantly correlated with tryptophan (r = 0.907). Therefore, the enhancement in melatonin could be due to both the occurrence of tryptophan and the new synthesis by yeast. In summary, the enhancement of melatonin in novel fermented orange beverage would improve the health benefits of orange juice by increasing this bioactive compound.

Occurrence and contribution of alkyl methoxypyrazines in wine tainted by Harmonia axyridis and Coccinella septempunctata

Ladybug taint (LBT) is a wine fault caused by the inadvertent incorporation of ladybeetles to the wine during the winemaking process. Harmonia axyridis, also known as the multicolored Asian lady-beetle (MALB), was the only species considered responsible for causing the taint. A second species, Coccinella septempunctata (7 Spot), has recently also been implicated. The main objectives of this study were to identify and quantify the compounds associated with ladybug taint of white and red wine from these two Coccinellidae species (Harmonia axyridis and Coccinella septempunctata), and determine the most odor-active compounds in LBT-affected wines. Results show that Coccinellidae can contribute dimethyl, isopropyl, secbutyl and isobutyl methoxypyrazine to wine when they are processed with grapes, and that the methoxypyrazine composition varies between MALB and 7 Spot. Isopropyl methoxypyrazine is the major contributor to LBT in wines produced with these ladybeetle species, although secbutyl and isobutyl methoxypyrazine may contribute in MALB- and 7 Spot-affected wines, respectively. Finally, dimethyl methoxypyrazine is reported for the first time in wines not affected by Coccinellidae; the global significance and prevalence of this compound in wine remains to be determined. Both Harmonia axyridis and Coccinella septempunctata can contribute alkyl methoxypyrazines, and particularly isopropyl methoxypyrazine, to wine at concentrations that can have a negative impact on wine quality. These findings will allow grape growers and winemakers to be more aware of the risks posed by 7 Spot beetles, and to take the appropriate preventative and remedial actions. Furthermore, this is the first time dimethyl methoxypyrazine is reported in wine, either as an endogenous or Coccinellidae-derived odorant.

3-Methyl-2-butene-1-thiol: Identification, analysis, occurrence and sensory role of an uncommon thiol in wine

A highly uncommon odorant, 3-methyl-2-butene-1-thiol was detected by using Gas Chromatography-Olfactometry (GC-O) and unequivocally identified for the first time in wine. A purge and trap sampling technique which provides highly representative extracts for olfactometric analysis was used for the extraction of the volatile fraction of a Spanish red wine made from Prieto Picudo grapes. The identification of the odorant was achieved by multidimensional gas chromatography analysis of the same purge and trap extract. Mass spectrum and retention indices in both polar and non-polar columns allowed knowing unequivocally the identity. To obtain quantitative data a method was validated for the analysis of the compound at ngL−1 level with acceptable precision. This powerful odorant presented an odor threshold in wine of 0.5–1ngL−1 and it has been detected in several Prieto Picudo wines at concentrations slightly above the odor threshold.

Development, validation and application of a specific method for the quantitative determination of wine esters by headspace-solid-phase microextraction-gas chromatography–mass spectrometry

A method for specifically quantifying 32 apolar esters in wine is reported that employs head space solid phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC–MS). A dozen esters were studied for the first time in wines, among them methyl trans-geranate, never reported in red wines until now. The target esters were apolar but bore a broad range of functional groups and have concentrations ranging from mg/l to ng/l levels; polar esters being effectively extracted by dichloromethane. Extraction and desorption conditions were optimised to obtain the best compromise for the simultaneous analysis of all 32 studied esters. To provide specificity for the method, deuterated ethyl esters were used as internal standards. These were ethyl-d 5 butyrate, hexanoate, octanoate and cinnamate, synthesised from the appropriate acyl chloride and ethanol-d 6. The esters were quantified in the wines with satisfactory repeatability (1.8% < RSD < 11.2%), reproducibility (1.5% < RSD < 15%), sensitivity (0.4 ng/l < LOQ < 4 μg/l), accuracy and specificity. The validation was carried out with several wine types as matrices (red, dry and sweet white). The optimised method was applied to 19 French wines and the results confirmed some well established oenological principles and opened prospects for further study on wine esters that had not been previously measured.

A HPLC fluorescence-based method for glutathione derivatives quantification in must and wine

A simple and automated high performance liquid chromatography (HPLC) method for the separation and quantitative determination of γ-glutamylcysteine and reduced glutathione (GSH) in wines is reported. This technique involves the use of a pre-column derivatization with 2,3-naphthalenedialdehyde (NDA), an isocratic separation in presence of β-cyclodextrine and a fluorimetric detection. The quantification of oxidized glutathione (GSSG) has also been studied, for the first time in wines, using an additive pre-derivatization step for reduction using glutathione reductase. The method has been designed for use in laboratories with limited equipment. The assay has been optimized and presents very good performances in terms of sensitivity and selectivity. Then, it has been validated for linearity, LOD, LOQ, precision and accuracy.

Identification of free disaccharides and other glycosides in wine

Free soluble carbohydrates of different wine samples were analyzed by GC–MS as their trimethylsilyloximes using a methylsilicone column. Besides α,α-trehalose, several β-glucosylglucoses such as cellobiose, sophorose, laminaribiose and gentiobiose were the main disaccharides identified. With the exception of gentiobiose, these disaccharides are now reported for the first time in wine. Lactose (4-O-β- d-galactopyranosyl- d-glucose), previously described in this product, was also tentatively identified. Several free glycosides: β-ethyl-glucoside and seven glyceryl-glycosides (including glucosides and galactosides) were also identified for the first time in wine. On the contrary, disaccharides in grape juice were mainly constituted of fructose derivatives, including sucrose, and no glycosides were detected. Although the total amount of disaccharides was different in white wines (<50 mg/L) from those in rosé and red wines (80–130 mg/L), the chromatographic profile was noticeably similar in all wine samples. The method here reported allows the identification of several carbohydrates which have not been previously detected in wines and could contribute to increase the understanding of enzymatic activity during winemaking.

Modeling Quality of Premium Spanish Red Wines from Gas Chromatography−Olfactometry Data

The aroma compositions of 25 premium Spanish red wines have been screened by quantitative gas chromatography-olfactometry and have been related to the quality scores of the wines. The study has shown that up to 65 odorants can be present in the aroma profiles of those wines, 32 of which have been detected in less than half of the samples. One new odorant is reported for the first time in wine [(Z)-2-nonenal], and only 11 odorants, most of them weak and infrequent, remain unknown. Quality was not positively correlated with any single compound or with any olfactometric vector built by the summation of odorants with similar odors. However, an olfactometric vector built by the summation of the olfactometric scores of defective odorants, such as 2-methoxy-3,5-dimethylpyrazine, 4-ethylphenol, 3-ethylphenol, 2,4,6-trichloroanisole, and o-cresol was significant and negatively related to quality. Quality could be satisfactorily explained by a simple partial least-squares model (79% explained variance in cross-validation) with just three X-variables: the aforementioned defective vector, a second vector grouping 9 other compounds with negative aroma nuances, and the fruity vector, grouping 15 compounds with fruit-sweet descriptors. This result shows that the quality of these red wines is primarily related to the presence of defective or negative odorants, and secondarily to the presence of a relatively large number of fruit-sweet odorants. Remarkably, only in a few low-quality samples could defective aroma nuances be detected, which suggests that defective and negative odorants exert a strong aroma suppression effect on fruity aroma.

Occurrence and Significance of Quercitol and Other Inositols in Wines during Oak Wood Aging

Inositols (quercitol, <i>chiro</i>-inositol, <i>scyllo</i>-inositol, and <i>myo</i>-inositol) were analyzed in commercial wines, in samples of experimental wines, in wines aged in oak barrels from different origins and with different time of usage, and in oak chip-treated wines. <i>chiro</i>-Inositol and quercitol were documented for the first time in wine. <i>chiro</i>-Inositol seemed to be a component arising from grapes, together with other cyclitols such as <i>myo</i>-inositol and <i>scyllo</i>-inositol, whereas quercitol was only found in oak-aged wines. <i>chiro</i>-Inositol was not detected in some commercial wines, indicating that the amount of this cyclitol could change with grape variety. The concentration of quercitol increased with aging time and depended on the age and characteristics of the barrels, but not on the grape variety used. For the other cyclitols, aging in oak barrels did not appreciably modify the concentration in each batch. In oak chip-treated wines, quercitol was also present and its concentration was influenced by chip size. Quercitol seems to be a potential new indicator of the contact of wine with oak wood.

Hopeaphenol: The First Resveratrol Tetramer in Wines from North Africa

Grapes and wines are now known to constitute a rich source of phenolics such as stilbenes and flavonoids. These compounds have been shown to have cancer chemopreventive activity and potential beneficial effects on cardiovascular diseases thanks to their antioxidant and antiplatelet properties. However, because little is known about African wines and their phenolic compositions, we investigated wine samples from North Africa. A three-step method was used for the fractionation of the Merlot variety wine: column chromatography followed by centrifugal partition chromatography and reversed-phase semipreparative high-performance liquid chromatography (HPLC). Six polyphenolic compounds of the Merlot variety (from Algeria) were isolated and identified by NMR spectroscopy, five of which are known (trans-resveratrol, trans-piceid, trans-epsilon-viniferin, pallidol, and astilbin) and one that is reported for the first time in wine, (+)-hopeaphenol, a stilbene tetramer. Furthermore, these molecules were quantified in 10 commercial wines from North Africa by means of an analytical HPLC system coupled with diode array detection. Differences in concentrations were found ranging in mg/L from 4.6 to 45 (trans-piceid), 0.66 to 3.45 (trans-resveratrol), 0.2 to 1.2 (trans-epsilon-viniferin), 0.2 to 9.2 (pallidol), 0.3 to 3.8 (hopeaphenol), and 10.8 to 24.22 (astilbin). Such a high level of pallidol and astilbin has never been recorded in wine. North African wines may contribute to a significant proportion of dietary intake of stilbene and astilbin, which may have health benefits.

Identification of three novel compounds in wine by means of a laboratory-constructed multidimensional gas chromatographic system

A laboratory-made off-line multidimensional GC–GC system has been optimized and applied to the isolation and identification of three novel aroma compounds in wine. The system comprises two independent chromatographs equipped with four-port manually actuated valves and fast capillary connectors that make it possible to quickly transfer a capillary trapping loop from the first to the second system. The first system includes a split/splitless injector, a thick phase semi-capillary column, the valve and both a flame ionization detection (FID) system and a sniffing port. The trapping loop lies outside the chromatograph and it is immersed in a Dewar with liquid nitrogen. The second system includes a programmable temperature vaporization (PTV) injector, the valve, the analytical column and two parallel detectors (a MS system and a sniffing port). The injection of large sample volumes (90 μl) in the first GC system and the general operation of the system have been optimized. The extract was obtained by purging the wine at 37 °C with a stream of nitrogen and trapping the volatiles in a bed containing 1 g LiChrolut EN. Fatty acids and alcohols were removed by washing the resins with a water/methanol solution containing 1% NaHCO 3, and volatiles were recovered with dichloromethane. The GC–MS analysis of the cuts obtained in the first GC system made it possible to identify by first time in wine the strong smelling compounds ethyl 2-, 3- and 4-methylpentanoate.

Determination of Stilbenes (δ-viniferin, trans-astringin, trans-piceid, cis- and trans-resveratrol, ε-viniferin) in Brazilian Wines

Phenolics from grapes and wines can play a role against oxidation and development of atherosclerosis. Stilbenes have been shown to protect lipoproteins from oxidative damage and to have cancer chemopreventive activity. We describe a method for the direct determination of stilbenes in several red wines using high-performance liquid chromatography with UV detection. In a survey of 12 commercial wines from the south of Brazil (Rio Grande del Sul), levels of delta-viniferin are reported for the first time in different varieties of red wines. Brazilian red wine contains trans-astringin, trans-piceid, trans-resveratrol, cis-resveratrol (in high quantity: 5 times more than the trans form), epsilon-viniferin, and a compound isolated for the first time in wine, trans-delta-viniferin. Isolation and identification of delta-viniferin was achieved by NMR after extraction and fractionation of red wine phenolics. delta-Viniferin contributes, as well as cis-resveratrol and trans-piceid, to a significant proportion of stilbenes in wine dietary intake, particularly with Merlot varieties containing an average level of 10 mg/L for delta-viniferin, 15 mg/L for cis-resveratrol, and 13 mg/L for trans-piceid. The total stilbene intake from wine origin was estimated for the Brazilian population as 5.3 mg/day per person (on the basis of a regular wine consumption of 160 mL/day). delta-Viniferin can contribute to around 20% of total stilbenes in wine (average of 6.4 mg/L in red Brazilian wines). It would be important in the future to investigate the origins of the differences in wine stilbene levels in relation to the vine varieties, and the bioavailability of the newly extracted stilbene delta-viniferin in plasma after consumption of different types of wines.

Aroma composition of wine studied by different extraction methods

Several isolation and concentration methods have been developed for the analysis of volatile components in wine. However, it is generally admitted that none of them fulfill all the requirements for the isolation of aroma compounds and that it is necessary to combine different extraction methods to obtain the complete volatile fraction. Three extraction methods have been studied: liquid–liquid extraction, static headspace and a new method developed in our laboratory, which has the same principle as the dynamic headspace technique. The volatiles were swept along with a carrier gas and later condensed in a cold trap. The advantages and disadvantages of the three methods regarding sample preparation, component losses and artifact formation, have been evaluated. Also, the sensitivity and reproducibility have been compared. With the liquid–liquid extraction method used, a new compound has been described for the first time in wine. This compound is 5,6,7,7a-tetrahydro-4,4,7a-trimethylbenzofuran-2(4H)-one. Liquid–liquid extraction and static headspace show good reproducibility; although static headspace is useful for the analysis of highly volatile compounds, it is not able to detect trace compounds due to its lack of sensitivity. The new method allows to obtain an extract, free of artifacts and foreign substances that were not in the original wine. As no solvent is used, the extracts may be tasted and sensorially analyzed.

Purification method for the isolation of monophosphate nucleotides from Champagne wine and their identification by mass spectrometry

Monophosphate nucleotides are difficult to identify in Champagne wine because they are present in small concentrations in a complex mixture. A method for the isolation, separation and identification of reference compounds, which achieved on average 79% recovery (except for cytidine derivatives), was developed and applied to wine. Some monophosphate nucleotides were then isolated from a Champagne wine aged on lees for 8 years, by ultrafiltration followed by a semi-preparative HPLC step using a strong anion-exchange column. The fraction obtained was subjected to HPLC in a reversed-phase column to remove the salt previously introduced, before identification of compounds by HPLC coupled to a mass spectrometer. For the first time in wine, 5′-IMP, 5′-AMP, 5′-CMP, 5′-GMP, 5′-UMP and the 3′- and/or 2′-isomers of the four latter compounds were identified by comparing their HPLC and electrospray ionization mass spectrometry data with those of reference nucleotides.

Approaches to wine aroma: release of aroma compounds from reactions between cysteine and carbonyl compounds in wine.

Under conditions close to those of wine, that is, low pH, aqueous medium, and low temperatures, this work examines the role of carbonyl (acetoin and acetol) and dicarbonyl (glyoxal, methylglyoxal, diacetyl, and pentane-2,3-dione) compounds associated with cysteine in the formation of odorous products. In particular, thiazole, 4-methylthiazole, 2-acetylthiazole, and trimethyloxazole and two sulfur and oxygenated heterocyclic compounds, 2-furanmethanethiol and thiophene-2-thiol, are examined. For thiophene-2-thiol, the reactional mechanism is proposed. Attempts were made to detect these compounds in wines from various origins. Certain molecules were identified for the first time in wine.

Identification of Volatile and Powerful Odorous Thiols in Bordeaux Red Wine Varieties

The use of a new technique combining low-temperature vacuum distillation with a specific chemical capture with an organomercuric compound enabled the extraction of volatile odorous thiols present at very low concentrations in the Bordeaux red wine varieties Merlot and Cabernet Sauvignon. The analysis of wine extracts by gas chromatography coupled with detection by olfactometry, flame photometry, and mass spectrometry led to the identification of three aromatic thiols: 3-mercapto-2-methylpropanol, identified for the first time in wine; 3-mercaptohexanol; and 3-mercaptohexyl acetate, already described in Sauvignon Blanc wines.