The anthocyanin profile of young wines made from Vitis vinifera cv. Graciano was determined by liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) and compared with that of ...Vitis vinifera cv. Tempranillo and cv. Cabernet Sauvignon. Thirty-four anthocyanins and anthocyanin-derived pigments, including pyruvic acid, 4-vinylphenol, and vinylflavanol, plus direct and acetaldehyde-mediated condensation products, were found by direct analysis. Of particular interest was the presence of the cis isomer of malvidin-3-(6''-p-coumaroylglucoside), reported here in wine for the first time. Anthocyanins in Graciano wines were characterized by a high level of peonidins and equal distribution between acetyl and cinnamoyl glucosides in comparison with Tempranillo and Cabernet Sauvignon wines. The occurrence of anthocyanin-derived pigments in the different wines appeared to be related to the concentration of the corresponding anthocyanin precursors.
In many cultivars of Vitis vinifera periods of mild water stress during ripening are thought to increase grape quality for winemaking, even though yields may be negatively affected. Because abscisic ...acid (ABA) is involved in the signaling of water stress in plants, we examine the effects of the ABA signal being given without the concomitant water stress. ABA at 250 mg l⁻¹ was sprayed weekly or biweekly from bud-burst until harvest onto the leaves of vineyard-grown plants of cv. Cabernet Sauvignon. For ABA-treated plants berry yield per bunch and per plant was significantly increased (1.5- to 2.0-fold) across three consecutive harvests (2005 through 2007). Number of berries per bunch and per plant was the primary basis for the significant crop increases, although bunches per plant also tended to increase (1.1- to 1.3-fold) across all three harvests. Other parameters assessed included number of internodes, shoot length, leaf area, leaf water potential at midday, photosynthesis, and stomatal conductance. These parameters showed no significant change with ABA treatment, although shoot length tended to be reduced, as was leaf area relative to control plants. The significantly increased fruit yields were thus accomplished without accompanying increases in leaf photosynthesis and leaf areas. Juice at harvest had equal levels of sugars (Brix) and somewhat higher levels of anthocyanins and total polyphenols relative to control values. The two latter trends continued for the resultant wine across two vintage years. In conclusion, three seasons of experimental trials have demonstrated that ABA application can significantly enhance yield per plant in the field-grown grape (cv. Cabernet Sauvignon) by favoring increased berry set without diminishing the quality of the fruit for winemaking use.
Strains of Oenococcus oeni performing malolactic fermentation might prove an interesting source of beta-glucosidase enzymes, which can release aromatic volatile compounds from their flavorless ...glycoconjugate precursors present in wine. Many studies have been conducted using strains cultured in winelike media, but little is known about the activity of these strains in real wine. In this work, real Cabernet Sauvignon red wine was used as the culture medium to test beta-glucosidase activity and bgl gene expression of four O. oeni strains. Assays in wine were compared with winelike medium and mixtures of wine and MRS broth medium. beta-Glucosidase activity was detected in both whole-cell and supernatant fractions for all four strains tested, although results varied depending on the conditions. The highest activity was found in wine (4 U/mg) and the activity was inhibited in the presence of fructose. To measure bgl expression, the RNA of O. oeni was extracted directly from red wine for the first time. Using real-time qPCR, the relative expression of the bgl gene was evaluated. The expression of this gene varied depending on the strain and it was overexpressed in samples of wine diluted with MRS. These results could be of importance to the wine industry and in studies of strain adaptation to wine for the selection of starters.
Benzenemethanethiol, a volatile thiol with a strong empyreumatic aroma reminiscent of smoke, has been identified in boxwood (Buxus sempervirens L.) as well as in red and white Vitis vinifera L. ...wines. The perception threshold in a model hydroalcoholic solution is ∼0.3 ng/L. All of the wines analyzed for this study contained this compound in concentrations of several dozen nanograms per liter. The Chardonnay wines had 30−40 ng/L. Sensory discrimination between a wine containing 7 ng/L benzenemethanethiol and the same wine with an additional 4 ng/L is very significant; the difference in smell is described as “empyreumatic”. This compound can therefore significantly contribute to the aroma of certain wines (Sauvignon Blanc, Semillon, Chardonnay, etc.) containing concentrations as high as 30−100 times higher than their perception threshold. Keywords: Benzenemethanethiol; boxwood; Sauvignon Blanc; Chardonnay; Semillon; smoky aroma
Because there is not a single method for carrying out phenolic ripening analysis, it is very difficult to compare the results obtained by different researchers. In this study, the three most widely ...used extraction methods of polyphenols (Glories, AWRI, and ITV) have been analytically compared by evaluating two of the most important parameters for the wine industry: total polyphenols and total anthocyanins. Samples from different grape varieties (Tempranillo, Garnacha, Cariñena, Syrah, Merlot, and Cabernet Sauvignon), from three different vintages (2006, 2007, and 2008), and at different ripening states (from the beginning of ripeness until harvest) were analyzed to obtain a wide range of representative phenolic contents. To avoid external interferences on the comparisons, the same grape puree was used to make the maceration assays using the different solvents according to each extraction method. Although every extraction method exhibits a different extraction efficiency, the correlation between the results obtained with each one was very good both for total anthocyanins and for total polyphenols. Thus, after having determined a parameter value of the phenolic ripeness using a specific method, the relationship found can be used to predict the parameter value of the phenolic ripeness provided by the other two methods.
Proanthocyanidins in grape berries are synthesised mainly before véraison, and very little attention is paid to the evolution of proanthocyanidins (PAs) in grapes from véraison to harvest. The ...present study focused on the changes of flavan-3-ols with different degrees of polymerisation in grape skins and the difference in proanthocyandin composition of 'Shiraz', 'Cabernet Sauvignon' and 'Marselan' grapes (Vitis vinifera L.). The results show that the content of flavan-3-ols, the percentage of prodelphinidins (%P) and mean degree polymerisation (mDP) found in 'Cabernet Sauvignon' berry skins at post-véraison were higher than those in 'Shiraz' and 'Marselan' skins. Only monomelic, dimeric, trimeric and polymeric flavan-3-ols were detected in the three grape cultivars. Polymers with more than tenfold flavan-3-ol units accounted for a relatively high proportion in grape berry skins, and the content in the three cultivars declined continuously during ripening. Principal component analysis showed that proanthocyanidin content, composition and mDP at grape harvest stage depended strongly on grape cultivar. This study provides some useful information for understanding the accumulation of PAs during berry maturation and this information can be used to improve wine quality.
In order to establish the dynamics of the physical-chemical parameters of flavoured wines and vermouth type wines, obtained by the addition of hydroalcoholic macerates from plants to the Sauvignon ...Blanc wine variety, we analyzed certain physical and chemical characteristics (D 20 20, Alcool %, Total dry extract g/l, Free sugar g/l, Unreducing extract g /l, Total Acidity g/l C4H6O6, Free SO2 mg/l Total SO2 mg/l) for 9 samples. Compared to the main wine parameters, the tested parameters had the following evolution: Alcoholic strength, Free sugar and Density increased in vermouth type wines, Total acidity decreased slightly in flavoured wines and more obvious in vermouth type wines. The total dry extract increased sharply in vermouth type wines and the unreducing extract decreased sharply in vermouth type wines. The amount of Free SO2 was higher in flavoured wines, but Total SO2 had lower values, both for flavoured wines and vermouth type wines, comparative to Sauvignon Blanc wine. Plants macerates added to the Sauvignon Blanc basic wine, influenced most of the physical-chemical parameters and provided new qualitative features to resulting beverages.
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