SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Merlot

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The impact of wine pH and closure type on colour, tannin concentration and composition was investigated. A single vintage of Cabernet Sauvignon wine was divided into three batches, the pH adjusted to 3.2, 3.5 or 3.8, the wines bottled under screw caps with either SaranTin™ (ST) or Saranex™ (Sx) liners. After 24 months, the tannin concentration, tannin % yield (relating to the proportion of acid-labile interflavan bonds) and the mean degree of polymerization (mDp) had decreased significantly, all of which can contribute to the softening in wine astringency with aging. The higher pH wines contained less % (-)-epicatechin 3-O-gallate subunits, while the Sx pH 3.2 wines were significantly lower in % yield and mDp than the other wines. Overall, the tannin structure and wine colour of the lower pH wines (pH 3.2) bottled under Sx screw caps changed more rapidly with aging than those of the higher pH wines (pH 3.8) bottled under ST screw caps.

Concepts: Polyphenol, Chilean wine, Tannin, Merlot, Bottle, Oenology, Wine, Cabernet Sauvignon

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The effects of prefermentation addition of 5 exogenous tannins with different-origin anthocyanins and color characteristics were investigated in “Cabernet Sauvignon wines” at the end of alcoholic fermentation and the end of malolactic fermentation, and after 6 mo and 9 mo of bottle aging, respectively. The results showed that the application of GSKT2 could significantly retard the degradation of most anthocyanins in the process of alcoholic fermentation and the decrease of some pyranoanthocyanins during the subsequent 3 stages, thus causing more yellowness of wine in comparison with the control. Three other condensed tannins, GSKT1, QUET, and GSET, had a positive impact only on several anthocyanin components. Four condensed tannins all contributed to more redness, suggesting that the action mechanism might be to protect wine against oxidation or contribute to form copigmented anthocyanidins, or polymeric pigments. The application of FOLT (hydrolysable tannin) did not produce any influence on wine redness even after 9 mo of bottle aging. This work provides some reasons for the reasonable application of tannin additives. Practical Application:  The prefermentative application of condensed tannins overall could protect some pigment components from degradation and enhance wine redness. Tannin additives with different origins have different effectiveness. The tannin additive obtained from grape skins, like GSKT2, could produce significant promotion on both redness and yellowness in wine. The prefermentation addition of hydroxylase tannin like FOLT seems not to have a significant effect on wine color.

Concepts: Polyphenol, Merlot, Alcoholic beverage, Fermentation, Tannin, Oenology, Wine, Cabernet Sauvignon

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The aromatic descriptor “green”, reflecting grape unripeness in French red wines, is frequently associated with the levels of 3-alkyl-2-methoxypyrazines, particularly 3-isobutyl-2-methoxypyrazine (IBMP), which has bell pepper nuances. Nevertheless, not all green aromatic expressions in red wines correlate with 3-alkyl-2-methoxypyrazine concentrations. This study considered sensory and chemical approaches using Cabernet Sauvignon wines obtained from grapes harvested at one-month intervals during the 2014 and 2015 vintages to investigate other volatile odoriferous compounds. Semipreparative HPLC fractionation of wine extracts revealed a fraction with specific green aromas in the early harvest wines. Its sensory impact was confirmed by omission and reconstitution tests. Then, multidimensional gas chromatography coupled with olfactometry and mass spectrometry (MDGC-O-MS/TOF) was used for molecular characterization of the aroma compounds associated with the green aromas. Surprisingly, eucalyptol (1,8-cineole), with menthol odor was highlighted and assayed at concentrations sometimes above its olfactory detection threshold in Cabernet Sauvignon and Fer Servadou wines. Sensory tests confirmed its impact at several concentrations detected in French red wines (up to 2.61 ± 0.03 μg/L) on the menthol nuance and overall green perception, particularly via an additive effect with IBMP. Quantitation of 1,8-cineole in Cabernet Sauvignon and Merlot grapes during berry development in 2015 revealed its varietal origin with abundant concentrations in unripe berries and decrease during grape maturation. Moreover, the implication of an invasive plant (Artemisia verlotiorum) growing in certain vineyards was shown to be responsible for increased 1,8-cineole concentrations in some wines.

Concepts: Bordeaux wine, Wine tasting descriptors, Grape, Grape varieties, Merlot, Fermentation, Cabernet Sauvignon, Wine

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One major red wine mouthfeel characteristic, astringency, is derived from grape-extracted tannins and is considered to be a result of interaction with salivary proteins and the oral mucosa. To improve our understanding of the role that the enthalpy of interaction of tannin with a hydrophobic surface (tannin activity) has in astringency perception, a chromatographic method was used to determine the tannin concentration and activity of 34 Cabernet Sauvignon wines, as well as sensory analysis done on 13 of those wines. In addition, astringency-relevant matrix parameters (pH, titratable acidity, ethanol, glucose, and fructose) were measured across all wines. Tannin activity was not significantly correlated with any matrix variables and the perception of drying and grippy was not correlated with tannin concentration and activity. However, ethanol content was well related to mouthfeel attributes and appeared to drive perceived drying. Although fructose and glucose content were well correlated, they did not drive the perception of sweetness, that is explained by the well-known mixture suppression effect.

Concepts: Sense, Enzyme, Merlot, Fermentation, Tannin, Ethanol, Wine, Cabernet Sauvignon

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The structural characterization of the polysaccharides and in vitro anti-inflammatory properties of Cabernet Franc (WCF), Cabernet Sauvignon (WCS) and Sauvignon Blanc (WSB) wines were studied for the first time in this work. The polysaccharides of wines gave rise to three fractions of polysaccharides, namely (WCF) 0.16%, (WCS) 0.05% and (WSB) 0.02%; the highest one was chosen for isolation of polysaccharides (WCF). It was identified the presence of mannan, formed by a sequence of α-d-Manp (1 → 6)-linked and side chains O-2 substituted for α-d-mannan (1 → 2)-linked; type II arabinogalactan, formed by (1 → 3)-linked β-d-Galp main chain, substituted at O-6 by (1 → 6)-linked β-d-Galp side chains, and nonreducing end-units of arabinose 3-O-substituted; type I rhamnogalacturonan formed by repeating (1 → 4)-α-d-GalpA-(1 → 2)-α-L-Rhap groups; and traces of type II rhamnogalacturonan. The polysaccharide mixture and isolated fractions inhibited the production of inflammatory cytokines (TNF-α and IL-1β) and mediator (NO) in RAW 264.7 cells stimulated with LPS.

Concepts: Merlot, Bordeaux, Grape varieties, Bordeaux wine, Chilean wine, California wine, Sauvignon blanc, Cabernet Sauvignon

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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-1range, were easily quantified for the first time in wine.

Concepts: Fermentation, Cabernet Sauvignon, Merlot, Bordeaux, Bordeaux wine, Analytical chemistry, Wine

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This work reports the identification of volatile compounds involved in the particular and atypical flavor detected in Vitis vinifera red Merlot and Cabernet Sauvignon wines made with grapes infected and wilted by brown rot (Plasmopara viticola). Must made from withered grapes had green aromas while red wines were marked by intense odor reminiscent of green, herbaceous notes but also figs and cooked fruit. Thanks to GC-O and GC-MS analysis, cooked fruit notes were identified as 3-methyl-2,4-nonanedione, γ-nonalactone and γ-decalactone, whereas herbaceous and green aromas were identified as (Z)-1,5-octadien-3-one and 3-isobutyl-2-methoxypyrazine. We show that the organoleptic impact of P. viticola is more pronounced in Merlot wines compared to Cabernet Sauvignon ones. The highest levels of 3-methyl-2,4-nonanedione (75.3ng/L) were found in old Merlot wines made with 20% infected berries, suggesting the incidence of berry quality on the ability of a wine to age.

Concepts: Berry, Chilean wine, Bordeaux wine, Merlot, Vitis vinifera, Grape, Wine, Cabernet Sauvignon

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To develop a robust tool for Chinese commercial wines' varietal, regional, and vintage authentication, phenolic compounds in 121 Chinese commercial dry red wines were detected and quantified by using high-performance liquid chromatography triple-quadrupole mass spectrometry (HPLC-QqQ-MS/MS), and differentiation abilities of principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA) were compared. Better than PCA and PLS-DA, OPLS-DA models used to differentiate wines according to their varieties (Cabernet Sauvignon or other varieties), regions (east or west Cabernet Sauvignon wines), and vintages (young or old Cabernet Sauvignon wines) were ideally established. The S-plot provided in OPLS-DA models showed the key phenolic compounds which were both statistically and biochemically significant in sample differentiation. Besides, the potential of the OPLS-DA models in deeper sample differentiating of more detailed regional and vintage information of wines was proved optimistic. On the basis of our results, a promising theoretic design for wine authentication was further proposed for the first time, which might be helpful in practical authentication of more commercial wines.

Concepts: Varietal, Merlot, Principal component analysis, New World wine, Chilean wine, Chromatography, Cabernet Sauvignon, Wine

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Weather conditions throughout the year have a greater influence than other factors (such as soil and cultivars) on grapevine development and berry composition. Temperature affects gene expression and enzymatic activity of primary and secondary metabolism which determine grape ripening and wine characteristics. In the context of the climate change, temperatures will probably rise between 0.3°C and 1.7°C over the next 20 years. They are already rising and the physiology of grapevines is already changing. These modifications exert a profound shift in primary (sugar and organic acid balance) and secondary (phenolic and aromatic compounds) berry metabolisms and the resulting composition of wine. For example, some Bordeaux wines have a tendency toward reduced freshness and a modification of their ruby color. In this context it is necessary to understand the impact of higher temperatures on grape development, harvest procedures, and wine composition in order to preserve the typicity of the wines and to adapt winemaking processes.

Concepts: Metabolism, Merlot, Bordeaux, Bordeaux wine, Cabernet Sauvignon, Grape, Vitis vinifera, Wine

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Although B. bruxellensis continues to be a problem during red winemaking due to formation of off-odors and flavors, few interactions between intrinsic and extrinsic conditions that would limit spoilage have been identified. Using a commercially-prepared Merlot wine, a 3 × 2 × 2 complete factorial design was implemented with total SO2 (0, 60, or 100 mg l(-1) ), ethanol (13% or 14.5% v v(-1) ), and storage temperature (15 or 18C) as variables. Populations of two strains of B. bruxellensis isolated from Washington wines (I1a and F3) were monitored for 100 days before concentrations of 4-ethylphenol, 4-ethylguaiacol, and volatile acidity were measured. In wines with 13% v v(-1) ethanol and stored at 15C, addition of 100 mg l(-1) total SO2 resulted in much longer lag phases (>40 days) compared to wines without sulfites. At 14.5% v v(-1) ethanol, culturability did not recover from wines with 100 mg l(-1) total SO2 regardless of the storage temperature (15 or 18C). A few significant interactions were noted between these parameters which also affected synthesis of metabolites. Thus, SO2 , ethanol concentration, and storage temperature should be together used as means to reduce infections by B. bruxellensis. This article is protected by copyright. All rights reserved.

Concepts: All rights reserved, Merlot, Brettanomyces, Copyright, Oenology, 4-Ethylphenol, Yeast, Wine