Search Results (11)

In contrast with the elaboration of still wines, the impact of barrel aging before the “prise de mousse” on the aging potential of Champagne base wines has not been studied so far. In the present study, the oxidative stability and related molecular fingerprints of Chardonnay Champagne base wines were reported after 1 year of on lees ageing in new oak barrels for two consecutive vintages. Regardless of the vintage, on lees ageing in new oak barrels improved the wines’ oxidative stability estimated by DPPH assay at 1 year, while UHPLC-Q-ToF-MS molecular profiling showed clear chemical modifications according to the ageing period. Oak wood molecular ellagitannins followed a linear extraction during barrel ageing for both vintages. However, the wines’ antioxidant metabolome composed by antiradical and nucleophilic compounds clearly appeared vintage- and barrel-aging dependent. These results enrich the understanding of white wines antioxidant metabolome and improve the knowledge of the ageing potential of Chardonnay Champagne base wines by integrating vintage- and barrel-ageing effects. Full article

The effects of reduced glutathione (GSH) on non-volatile and volatile metabolites of Chardonnay wine during storage under simulated oxidation were investigated. The metabolites of GSH, which play a key role in the storage of white wine, were identified. In this study, GSHs at 0, 10, and 20 mg/L were added to wine samples and stored at 45 °C for 45 days. Wine samples supplemented with 0 mg/L GSH were used as controls (CK). The samples stored for 45 days were analyzed via ultra-high performance liquid chromatography–tandem mass spectrometry and gas chromatography–tandem mass spectrometry. A total of 1107 non-volatile metabolites were detected, and 617 volatile metabolites were identified. Variable Importance in Projection (VIP) of >1.0 and Fold Change (FC) of ≧2.0 were used to screen differential metabolites. A total of 59 important non-volatile and 39 differential volatile metabolites were screened. Among the non-volatile metabolites, 17 substances were down-regulated, whereas 16 substances were up-regulated. Among the volatile metabolites, 3 substances were down-regulated, while 19 substances were up-regulated. After analysis, some lipids were found to play an important role in the changes to non-volatile substances. This study provides theoretical support for further application of GSH in increasing the oxidation stability of white wine. Full article

White wines’ oxidative stability is related to a flow of chemical reactions involving a number of native wine compounds comprising their antioxidant metabolome. By applying the combination of powerful and modern analytical approaches (EPR, DPPH, and UPLC-qToF-MS-based metabolomics), we could define wine antioxidant metabolome as the sum of molecular antioxidant markers (AM) characterized by their radical scavenging (AM-RS) and nucleophilic (AM-Nu) properties. The impact of on-lees barrel aging of chardonnay wines on the antioxidant metabolome was studied for two consecutive vintages. The identification of wines’ antioxidant metabolome allows for a detailed understanding of the transient chemical interplays involved in the antioxidant chemistry associated with well-known antioxidants and opens an avenue towards personalized winemaking. The present study gathers for the first time the dynamics of wines’ antioxidant metabolome during on-lees aging. Monitoring the variations of the wine antioxidant metabolome can provide an avenue to better control the winemaking process using the knowledge of how to optimize the wine aging potential. Full article

Wine is a kind of beverage with a variety of compounds beneficial to human health, which makes it popular all over the world and it contributes importantly to economics. The excessive oxidation of wine has always been a major problem in wine production and storage. Unlike traditional wines which are made from Eurasian grapes, wines made from muscadine grapes (Muscadinia rotundifolia Michx.) can maintain their sensory qualities under natural oxidation conditions for relatively long periods of time despite the insight mechanisms still being unclear. In this study, two muscadine wines, Carlos (CAL) and Noble (NOB), and two traditional wines, Chardonnay (CH) and Marselan (MAS), were chosen for comparison of their compositional alteration during oxidation, in order to analyze the principal components contributing to the antioxidant characteristics of muscadine wines. The DPPH, ORAC, color intensity, and total phenolic content changes during the natural oxidation process were analyzed. Six core significantly changed metabolites (SCMs, avicularin, beta-lactose, delphinidin-3-O-glucoside, ellagic acid, myricetin, and 4-methylcatechol [p < 0.05]) related to the oxidation process were determined. In addition, HPLC–MS was also used to identify pyrogallol which is a unique antioxidant compound in muscadine wine. The present work aims to reveal the crucial antioxidant compounds of muscadine wine and provide valuable information and a new platform for future research on wine oxidation. Full article

The influence of the technological processes of grape processing on the content of hydroxycinnamic acids and volatile phenolic substances in wine was studied. The method of targeted oxygenation was applied in grape processing technology of the Welschriesling and Chardonnay grape varieties. The content of volatile phenolic substances was determined by gas chromatography, the content of hydroxycinnamic acids by liquid chromatography, and the basic analytical parameters of the wine by FTIR spectrometry. The method of targeted must oxygenation had a statistically significant effect on the content of hydroxycinnamic acids and volatile phenolics in the wine. In all three monitored years (2015–2017), the content of 4-vinylphenol and 4-vinylguajacol in the wine significantly decreased. A significant dependence between the content of hydroxycinnamic acids and volatile phenolics was found. The experiment showed that a 1% increase in the content of hydroxycinnamic acids in the Chardonnay variety could result in an average increase in the content of monitored volatile phenolics by 3.6% (3 years’ data). Naturally reducing the content of hydroxycinnamic acids, with the application of technological processes, eliminated the oxidative processes during wine maturation. Sensory undesirable volatile phenolic substances were consequently formed in lower quantities, and there was no negative impact on the favourable sensory properties of wine. It was not necessary to use the polyvinylpolypyrrolidone adsorbents. Full article

We examined the effect of two different technological processes for wine production on qualitative parameters of wine. We used the reductive method, which is currently considered to be the conventional method, and a targeted must oxidation method. We evaluated the basic physicochemical parameters and sensory attributes of wine as well as the content of phenolic substances in wine, which are responsible for the oxidation processes. The vegetable materials used were the grape varieties, Welschriesling, Chardonnay, and Rheinriesling. The content of phenolic substances was determined by HPLC (high-performance liquid chromatography), and the basic analytical parameters of wine were determined by FT-IR (Fourier Transform Infrared Spectroscopy) spectrometry. The sensory analysis was evaluated according to the International Union of Oenologists. For each of the wines examined, the total content of phenolic substances decreased after the targeted oxidation method was applied. For the Welschriesling variety produced by the reduction method, the total content of the 19 monitored phenolic substances in the year 2015 was 88.37 mg·L⁻¹, and for the wine produced by target oxygenation, it was 68.63 mg·L⁻¹. This represents a decrease of 21.5%. In the year 2016, the decrease was 20.91%. By reducing the content of phenolic substances, the oxidation processes in wines are eliminated after bottling. Thus, there is less need for sulphating wines with a reduced content of phenols. Full article

The knowledge about the molecular fraction contributing to white wines oxidative stability is still poorly understood. However, the role of S- and N-containing compounds, like glutathione and other peptides, as a source of reductant in many oxidation reactions, and acting against heavy metals toxicity, or lipid and polyphenol oxidation as ROS-scavenger is today very well established. In that respect, the aim of the present study is to introduce an original analytical tool for the direct determination of the available nucleophilic compounds in white wine under acidic pH conditions. One step derivatization of nucleophiles has been realized directly in wines using 4-methyl-1,2-benzoquinone (4MeQ) as an electrophilic probe. Derivatization conditions considering probe concentration, pH, reaction time, MS ionisation conditions and adducts stability, were optimized using model solutions containing standard sulfur and amino compounds (GSH, Cys, HCys and Ser-Aps-Cys-Asp-Ser, Asp-Met, Met and Glu). Ultra-high-performance liquid chromatography coupled to a quadrupole-time of flight mass spectrometer (UHPLC-QqTOF-MS) analysis of up to 92 white wines from different cultivars (Chardonnay, Sauvignon and Semillon) followed by Multivariate analysis (PLS DA) and Wilcoxon test allowed to isolate up to 141 putative wine relevant nucleophiles. Only 20 of these compounds, essentially thiols, were detectable in samples before derivatization, indicating the importance of the quinone trapping on the revelation of wine unknown nucleophiles. Moreover, annotation using online database (Oligonet, Metlin and KEGG) as well as elementary formula determined by isotopic profile, provided evidence of the presence of amino acids (Val, Leu, Ile, Pro, Trp, Cys and Met) and peptides with important antioxidant properties. The complimentary set of MS/MS spectral data greatly accelerated identification of nucleophiles and enabled peptides sequencing. These results show that probing wines with 4-methyl-1,2-benzoquinone enhances thiols ionisation capacity and gives a better screening of specific S- N- containing functional compounds as part of the white wines antioxidant metabolome. Full article

The impact of oxygen exposure during winemaking on metal ion concentrations in wine were investigated throughout the winemaking process in a Chardonnay wine. The concentrations of Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sn, and Zn were determined using inductively coupled plasma-mass spectrometry. Oxygen exposure significantly impacted 13 metal ions at different phases of winemaking. However, only the concentrations of Cr, Cu, and Fe were impacted by early oxygen exposure during pressing, with lower Cr and Cu concentrations in wines that were aerobically pressed and lower concentrations of Fe in wines that were inertly pressed. The sequestering of Al, Cu, Ni, and Zn by wine lees was significantly affected by oxygen treatment, with lees collected from wines that were treated oxidatively sequestering significantly greater amounts of Cu and Zn and removing these metals from the wine supernatant. The metal ion that was most affected by oxygen exposure during pressing and handling was Cu, with significantly lower Cu measured in wines that were produced under oxidative conditions. It is known that elevated Cu concentrations have negative implications for wine aroma and flavour. This study demonstrated that oxygen management during winemaking significantly impacts metal ion concentrations in lees and wine, which may decrease the risk of developing taints and faults. Full article

The DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay is an easy and efficient method commonly used to determine the antioxidant capacity of many food matrices and beverages. In contrast with red wines, white wines are poorer in antioxidant polyphenolics, and the more hydrophilic sulfur-containing compounds in them may contribute significantly to their antioxidant capacity. The modification of the classical DPPH method, with a methanol-buffer and the measure of EC₂₀ (quantity of sample needed to decrease the initial DPPH concentration by 20%) has shown that sulfur-containing compounds such as cysteine (0.037 ± 0.003), glutathione (0.054 ± 0.003) or methanethiol (0.104 ± 0.003) appeared to bear antioxidant capacity comparable to well known phenolic compounds, such as catechin (0.035 ± 0.003), caffeic acid (0.057 ± 0.003) and ferulic acid (0.108 ± 0.003), respectively. In the case of white wines, the comparison with REDOX-sensory scores showed that results from this modified DPPH assay are strongly correlated with sensory attributes (r = 0.73, p < 0.1). These results provide an unprecedented illustration of the important contribution of these sulfur-containing compounds to the radical quenching ability of white wines. Full article

Chardonnay wines have a long-standing reputation regarding their aging potential. However, in some cases, they face premature oxidation a few years after bottling. Scientific reports are, for now, multiparametric and unclear. Polyphenols seem to be an important factor involved in the oxidative stability of white wines, but their role has not yet been completely characterized. The present study aimed to investigate the link between polyphenol content and the emergence of oxidative odors of bottle-aged Chardonnay wines. In order to obtain samples with noticeable differences in polyphenol content, as well as in sensory oxidative notes, wines from two different vintages were used. For each vintage, three levels of must clarification and two wine closures were implemented. Polyphenol content was analyzed chemically, and the oxidative character was assessed sensorially by a trained panel using a specific intensity scale. The results showed significant effects for closure type and turbidity. However, these effects were strongly affected by vintage. Concerning the polyphenol content, a clear difference was also found between vintages, closures and turbidity levels. Significant linear regression models for REDOX scores pointed out Flavon-3-ols as the main negative predictor, and grape reaction product (GRP) as the main positive predictor. The enological implications are discussed. Full article

The conducting polymer PEDOT (poly-3,4-ethylenedioxythiophene) has been polymerized onto 3 mm and 10 µm electrodes from a propylene carbonate solution. The electrodes have then been tested in a Chardonnay wine, including dilutions in a model wine solution, with comparisons made to scans with a glassy carbon electrode. A well-defined oxidation peak was obtained for the white wine at PEDOT in the 400 to 450 mV (Ag/AgCl) range, where peaks were also obtained for the representative phenolics caffeic acid and catechin. The voltammetry at PEDOT was typical of a surface-confined process. Significant preconcentration, leading to an increased current response, was noted over a period of 20 min of holding time. Extensive PEDOT growth was observed in the microelectrode case, leading to current densities for the oxidation of caffeic acid over 1000 times greater than those observed at the macroelectrode, matching the high surface area and fractal-type growth observed in SEM images. Full article