186,195 research outputs found
Wine metabolomics reveals new sulfonated products in bottled white wines, promoted by small amounts of oxygen
No full textThe impact of minute amounts of oxygen in the headspace on the post-bottling development of wine is generally considered to be very important, since oxygen can either damage or improve the quality of wine. This project aimed to gain new experimental evidence about the chemistry of the interaction between wine and oxygen. The experimental design included 216 bottles of 12 different white wines produced from 6 different cultivars (Inzolia, Muller Thurgau, Chardonnay, Grillo, Traminer and Pinot gris). Half of them were bottled using the standard industrial process with inert headspace and the other half without inert gas and with extra headspace. After 60 days of storage at room temperature, the wines were analysed using an untargeted LC-MS method. The use of a detailed holistic analysis workflow, with several levels of quality control and marker selection, gave 35 metabolites putatively induced by the different amounts of oxygen. These metabolite markers included ascorbic acid, tartaric acid and various sulfonated compounds observed in wine for the first time (e.g. S-sulfonated cysteine, glutathione and pantetheine; and sulfonated indole-3-lactic acid hexoside and tryptophol). The consumption of SO2 mediated by these sulfonation reactions was promoted by the presence of higher levels of oxygen on bottlin
Modified carbon paste electrodes for the voltammetric evaluation of early post-bottling oxidation of white wines: a proof of concept
No full textThe process of bottling entails exposure of wine to variable amounts of oxygen. Depending on oxygen levels, this can contribute to wine evolution during bottle storage, including occurrence of oxidative off-flavours. Due to the large compositional differences existing among wines, the type and extent of the chemical transformations due to oxygen exposure are wine dependent. Analytical approaches typically involving GC-MS and/or LC-MS allow detailed characterisation of these changes. However, at a winery level, rapid assessment of the oxidative changes due to oxygen exposure at bottling remains challenging. In this study, the use of modified carbon paste electrodes for the voltammetric assessment of early post-bottling oxidation has been investigated.
Ten commercial white wines from different grape varieties were bottled under controlled conditions to obtain two different degrees of oxygen exposure, ideally corresponding to good (NoOx) vs. average (Ox) bottling conditions. Free SO2, total SO2 and ascorbic acid at bottling were in the range of 37-42 mg/L, 97-123 mg/L, and 37-44 mg/L respectively. Either a lower or a higher oxygen ingress closures were used for NoOx and Ox wines respectively. After two months of cellar storage, samples analysed by linear sweep voltammetry using modified disposable carbon paste screen printed electrodes. Analyses were carried out in the 0-1200 mV range, with the obtained voltammograms providing a global profile of the pool of major white wine oxidizable substrates such as ortho-diphenols, phenolic acids, ascorbic acid and SO2.
NoOx wines showed relatively similar voltammetric profiles, although with different anodic current values, indicating differences in the concentrations of oxidizable substrates. Compared to NoOx samples, Ox wines generally exhibited a decrease in anodic current, with patterns that were wine depended. Oxidation fingerprints were obtained as difference of NoOx minus Ox voltammograms, revealing the existence of 4 different fingerprints across the 10 wines studied. Comparison of these oxidation fingerprints with those of a white wine spiked with pure compounds was attempted to assess the contribution of major wine compounds to the 4 fingerprints observed. Voltammetric data were also cross-compared with those obtained on the same wines using an untargeted LC-ESI-QTOF MS method, in a further attempt to evaluate the suitability of a rapid voltammetric approach to the evaluation of wine post-bottling oxidation
L’effetto dell’orientamento sulla temperatura interna in due edifici abitati di omologhe caratteristiche costruttive. Una campagna di misura in dieci appartamenti nell’estate 2004
No full textChanges in the contents of micro- and trace-elements in wine due to winemaking treatments
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How small amounts of oxygen introduced during bottling can influence the metabolic fingerprint of white wines
No full textThe impact of minute amounts of headspace oxygen on the post-bottling development of wine is generally considered to be very important, since oxygen, packaging and storage conditions can either damage or improve the quality of wine, in terms of its characteristics. Anecdotal evidence of the negative influence of oxygen on the quality of white wines is reflected in the generalised use of inert bottling lines, where the headspace between the white wine and the stopper is filled with an inert gas.
This project aimed to address some basic questions about the chemistry of the interaction between wine and oxygen, crucial for decisions regarding optimal closure. While it is known that similar amounts of oxygen affect different wines to a variable extent, our knowledge of chemistry is not sufficient to construct a predictive method. To obtain the widest coverage of the metabolic space, an untargeted method was used with a LC-MS instrument. The experimental design included 12 different wines produced using five different cultivars.10 samples of each wine were bottled using the standard industrial process, with inert headspace and variable exposure to oxygen (1.30 - 4.25 ppm O2), along with a further 10 bottles produced using the same line, but without inert gas and with extra headspace (5.93 - 8.38 ppm O2). After bottling, all the wines were stored for 60 days at room temperature. After storage, the wines were analysed using an untargeted LC-ESI-QTOF MS method, already optimised for wine analysis and adopted for other wine metabolomics experiments [1].
Instrumental analysis produced a dataset with over 20,000 features, and data analysis showed the presence of about 25 putative markers induced by different amounts of oxygen. The stability of the analysis in the experiment was sufficient to highlight several metabolites whose concentrations were influenced by the minute amounts of oxygen entering the wine during bottling in real conditions. The approach made it possible to compare the fate of metabolites already known to be influenced by oxygen, such as the exogenous antioxidants sulphur dioxide and ascorbate, in the same experiment, and to compare them with other endogenous wine constituents in order to obtain new information about wine chemistry
Archeologia, antropologia e isotopi. Le sepolture di San Martino di Lundo nel Trentino occidentale
No full textLC-MS metabolomics shows a smart way to reduce sulfites in wine
No full textWhat does happen in wine in the presence of oxygen? What is the fate of exogenous antioxidants such as SO2? A consortium between a winery, a wine stopper producer and a MS metabolomics laboratory, was build to answer the above questions towards an ambitious project. The experimental design included 216 bottles of 12 different white wines produced from 6 different cultivars (Inzolia, Muller Thurgau, Chardonnay, Grillo, Traminer and Pinot gris). Half of them were bottled using the standard industrial process with inert headspace and the other half without inert gas and with extra headspace. After 60 days of storage at room temperature, the wines were analysed using an untargeted LC–MS method [1].
The use of a detailed holistic analysis workflow, with several levels of quality control and marker selection, gave 35 metabolites putatively induced by the different amounts of oxygen. These metabolite markers included ascorbic acid, tartaric acid and various sulfonated compounds observed in wine for the first time (e.g. S-sulfonated cysteine, S-sulfonated glutathione and S-sulfonated pantetheine, sulfonated indole-3-lactic acid hexoside and sulfonated tryptophol). The consumption of SO2 mediated by these sulfonation reactions was promoted by the presence of higher levels of oxygen on bottling [1].
The reaction between SO2 and other antioxidants present in wine, like glutathione, results in depleting each other concentration [1]. So instead to have a synergic or additive protection due to the presence of multiple antioxidants, the wine is less protected from oxidations because of the antagonism between the antioxidants. This phenomenon, unknown until today, was pushing often winemakers to increase the added dose of SO2 without knowing why, and as result to increase sulfites concentration in wine
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