Francesca Fort

Influence of grape maturity and maceration length on color, polyphenolic composition, and polysaccharide content of Cabernet Sauvignon and Tempranillo wines.

The aim of this paper was to study how maturity and maceration length affect color, phenolic compounds, polysaccharides, and sensorial quality of Cabernet Sauvignon and Tempranillo wines at three stages of grape ripening. Ripeness increased color extractability, phenolic compounds, and polysaccharide concentrations. Moreover, the proanthocyanidin mean degree of polymerization (mDP) and the percentage of prodelphinidins also increased with maturity, whereas the percentage of galloylation decreased. In general, wines from riper grapes contain higher proportions of skin proanthocyanidins. Color and anthocyanin concentration decreased when the maceration was longer, whereas polysaccharide and proanthocyanidin concentrations did the opposite. It was also detected that the mDP and the percentage of prodelphinidins decreased when the maceration was extended, whereas the percentage of galloylation increased. These data seem to indicate that proanthocyanidin extraction from seeds is clearly increased throughout the maceration time.

Comparison of methods for estimating phenolic maturity in grapes: Correlation between predicted and obtained parameters

With the aim of determining the real predictive ability of three methods for measuring phenolic maturity (Glories, ITV and Cromoenos), representative grapes of Merlot, Cabernet sauvignon, Grenache and Tempranillo were harvested at three different ripening levels. The grapes were vinified by triplicate and were also used for phenolic maturity estimation. After that, color intensity, CIELAB coordinates, anthocyanins by spectrometry and HPLC and total phenolics were analysed in wines and also in the different extracts from the three extraction methods. Statistical analysis of data was carried out to determine the real performance of prediction of the different methods. Glories method predicted reasonably the color intensity, CIELAB coordinates and the concentration of anthocyanins and total phenolics in wine although it needs a lot of time and it requires working carefully. On the other hand, Cromoenos method predicted similarly or even better the color and phenolic composition of wine. This method also presents the advantage of being much faster and easier to apply. In contrast, although the ITV method provided reasonable results for anthocyanins and total phenolic compounds its color prediction was not adequate.

Effect of Two Different Treatments for Reducing Grape Yield in Vitis vinifera cv Syrah on Wine Composition and Quality: Berry Thinning versus Cluster Thinning

The influence of two treatments for reducing grape yield, cluster thinning and berry thinning, on red wine composition and quality were studied in a Vitis vinifera cv Syrah vineyard in AOC Penedès (Spain). Cluster thinning reduced grape yield per vine by around 40% whereas berry thinning only reduced it by around 20%. Cluster thinning grapes had higher soluble solids content than control grapes, and their resultant wines have greater anthocyanin and polysaccharide concentrations than the control wine. Wine obtained from berry thinning grapes had a higher total phenolic index, greater flavonol, proanthocyanidin, and polysaccharide concentrations, and lower titratable acidity than the control wine. Wines obtained from both treatments were sufficiently different from the control wine to be significantly distinguished by a trained panel in a triangular test. Even though both treatments seem to be effective at improving the quality of wine, berry thinning has the advantage because it has less impact on crop yield reduction.

Influence of wine pH on changes in color and polyphenol composition induced by micro-oxygenation.

The presence of oxygen in red wine leads to the transformation of ethanol into ethanal, which after capturing a proton will react with flavanols to start the process of forming ethyl bridges between flavanols and between flavanols and anthocyanins. Wine pH also conditions the equilibrium between the different anthocyanin structures and may thus affect anthocyanin reactivity. Consequently, the aim of this paper was to study how the pH can affect the changes induced by micro-oxygenation in two wines with different phenolic composition. The differences between micro-oxygenated wines and their controls were, in general, greater when the pH was more acidic. Specifically, the differences between micro-oxygenated wines and their corresponding controls in terms of color intensity, anthocyanin concentration, PVPP index, ethyl-linked pigments, B-type vitisins, polymeric pigments, and ethylidene-bridged flavanols were greater at lower pH. In contrast, the effects of micro-oxygenation when the pH was less acidic were much less evident and sometimes practically nonexistent. These results demonstrate for the first time that the pH of the wine has a great influence on oxygen-induced changes of color and phenolic compounds.

Oxygen consumption by oak chips in a model wine solution; Influence of the botanical origin, toast level and ellagitannin content.

The botanical origin, toast level and ellagitannin content of oak chips in a model wine solution have been studied in terms of their influence on oxygen consumption. French oak chips released significantly higher amounts of ellagitannins than American oak chips at any toast level. The release of ellagitannins by oak chips decreased as the toast level increased in the French oak but this trend was not so clear in American oak. Oxygen consumption rate was clearly related to the level of released ellagitannins. Therefore, oak chips should be chosen for their potential to release ellagitannins release should be considered, not only because they can have a direct impact on the flavor and body of the wine, but also because they can protect against oxidation.

A Fast, Efficient Method for Extracting DNA from Leaves, Stems, and Seeds of Vitis vinifera L.

A new method to extract DNA that can be applied to the leaves, seeds, and stems of Vitis vinifera uses a combination of dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB) and allows for optimal DNA extraction from recalcitrant tissues. The technique is as rapid as commercial kits and requires only small amounts of material. As it does not require RNase treatment, its application is approximately one-eighth of the cost. The possibility of applying the same DNA extraction method to different tissues is advantageous for two reasons: it diminishes a source of heterogeneity and it can be applied to samples obtained during any season of the year, including winter. The proposed method provides high-quality DNA with a good yield from the leaves, seeds, and stems of V. vinifera and guarantees identical results of posterior SSR analyses, regardless of the tissue used and the stage of ripening at which it was collected. Furthermore, since this method can be applied to stems, it can be used as a first step for quality control in grapevine nurseries.

Effect of Yeast Strain and Supplementation with Inactive Yeast during Alcoholic Fermentation on Wine Polysaccharides

Polysaccharides appear to exert some sort of positive sensory effect on wine composition. For this reason, attempts have been made to increase their concentration by strategies such as the use of yeast strains with a greater capacity for releasing polysaccharides and supplementation with inactive yeast pretreated to favor the release of polysaccharides. The aim of this study was to determine whether these new strategies are useful for enriching the polysaccharides in red wines. Our results confirm that both strategies provide wines with higher polysaccharide concentrations. Wines fermented with a high polysaccharide-releasing yeast strain had a 32% higher polysaccharide concentration than controls. Wines supplemented with inactive yeasts also had significant increases (11 to 20%) in polysaccharides.

Influence of grape maturity and maceration length on polysaccharide composition of cabernet sauvignon red wines

Cabernet Sauvignon grapes were harvested at three different degrees of maturity (~three, five, and seven weeks postveraison) and used for micro-scale vinifications. For each maturity, four different maceration lengths (one, two, three, and four weeks) were applied in triplicate to assess the influence of both maceration length and grape maturity on the composition of wine polysaccharides. The total concentration of wine polysaccharides was estimated by high resolution size exclusion chromatography-refraction index detection and the polysaccharides then underwent acidic hydrolysis. The neutral monosaccharides released were analyzed by ion exclusion chromatography using an HPLC-RID chromatographic system. The total concentration of wine polysaccharides increases with maceration length and with grape maturity. Both yeast polysaccharides (mannoproteins, MP) and some grape polysaccharides (polysaccharides rich in arabinose and galactose, PRAGs) increase with maceration length. However, grape maturity affects PRAGs and MPs differently: while PRAGs increase with the grape’s maturity, the opposite appears to be true of yeast polysaccharides.

The effect of supplementation with three commercial inactive dry yeasts on the color, phenolic compounds, polysaccharides and astringency of a model wine solution and red wine.

BACKGROUND Nowadays supplementing red wines with commercial inactive dry yeasts is a widespread practice in winemaking because it leads to better balanced wines through increased mouthfeel and smooth astringency. The aim of this article is to study, in a red wine and in a model wine solution, how supplementation with three commercial inactive dry yeasts affects chemical composition and astringency. This will give us a better understanding of the action mechanism involved. RESULTS The results suggest that this action mechanism is related to two different phenomena. The first is that inactive yeasts release polysaccharides and oligosaccharides which can increase mouthfeel and inhibit interactions between salivary protein and tannins. The second is that they have a direct effect on the precipitation or absorption of proanthocyanidins, especially the larger polymers, which have been described as the most astringent. CONCLUSION It can be concluded that supplementation with inactive yeasts is indeed a useful tool for smoothing the astringency of red wines.

SSR Analysis of 338 Accessions Planted in Penedès (Spain) Reveals 28 Unreported Molecular Profiles of Vitis vinifera L.

A collection of 338 grapevine accessions from 24 countries planted on the estates of Bodegues Sumarroca (AOC Penedès) was genotyped with 20 microsatellite markers. A total of 294 different molecular profiles were obtained; 28 of them are presented for the first time. Twenty-six accession names are considered new synonyms and are commonly used in several regions.