Grapevine-shoot stilbene extract as a preservative in red wine.

This paper reports the use of a grapevine-shoot stilbene extract (Vineatrol®) as a preservative in red wine. Its effectiveness to preserve red wine quality under two different winemaking systems (traditional and Ganimede) was studied at bottling and after twelve months of storage in bottle. Enological parameters, color related parameters, volatile composition, sensory analysis and olfactometric profile were evaluated. At bottling wines treated with Vineatrol showed higher color related parameters and higher score in sensory analysis than those treated with SO2. The use of SO2 increased ester and alcohol volatile compounds in relation to the use of Vineatrol. Wine olfactometric profile was modified by Vineatrol addition. Two new odorant zones with high modified frequency appeared in wines treated with Vineatrol. After 12months of storage in bottle, wines treated with Vineatrol showed parameters related to oxidation. The weak point of the process seemed to be the evolution during the storage in bottle.

Contribution of low molecular weight phenols to bitter taste and mouthfeel properties in red wines.

The aim of this study was to explore the relationship between low molecular weight compounds present in wines and their sensory contribution. Six young red wines were fractionated by gel permeation chromatography and subsequently each fraction obtained was separated from sugars and acids by solid phase extraction. Wines and both fractions were in-mouth evaluated by a trained sensory panel and UPLC-MS analyses were performed. The lack of ethanol and proanthocyanidins greatly increased the acidity perceived. The elimination of organic acids enabled the description of the samples, which were evaluated as bitter, persistent and slightly astringent. Coutaric acid and quercetin-3-O-rutinoside appear to be relevant astringent compounds in the absence of proanthocyanidins. Bitter taste was highly correlated with the in-mouth persistence. A significant predictive model for bitter taste was built by means of PLSR. Further research must be carried out to validate the sensory contribution of the compounds involved in bitterness and astringency and to verify the sensory interactions observed.

Taste and mouthfeel properties of red wines proanthocyanidins and their relation to the chemical composition.

The aim of this work is to assess the relationship between the in-mouth sensory properties of proanthocyanidins (PAs) and its chemical composition. To achieve such a goal, the proanthocyanidin fraction from six different young commercial red wines was obtained by gel permeation chromatography. A sensory panel, selected on the basis of their PROP status and trained in taste and mouthfeel sensations, described both the wines and fractions. MALDI-TOF-MS and UPLC-MS were used to identify thoroughly the polyphenolic composition of each proanthocyanidin fraction. The results showed that the PAs fractions were exclusively described as astringent and persistent. The astringent subqualities studied (velvety and puckering/drying) were mainly related to the quantity of proanthocyanidins and the proportion of the extension flavanol units linked to proanthocyanidins. A significant negative correlation was found between both of the astringencies (velvety and puckering/drying). Furthermore, both subqualities appeared to contribute to the persistence. A significant correlation was observed between the astringency and the persistence data of the wines and fractions. Significant multiple linear regressions were found between the sensory astringency data and the chemical compounds analyzed. The concentration of proanthocyanidins present in young red wines is the major determinant of the differences perceived in the astringency. Additionally, the extension flavanol units linked to the proanthocyanidins seem to have a different impact on the astringent subqualities.

Effect of cluster thinning and prohexadione calcium applications on phenolic composition and sensory properties of red wines.

The overall objective of this study was to investigate the effect of manual cluster thinning (CT) and the application of the growth regulator Prohexadione calcium (ProCa) on the phenolic composition and the sensory profile of Tempranillo and Grenache wines produced from treated vines in La Rioja (Spain). ProCa was applied at preblooming and CT was carried out at veraison in two consecutive years. Different physicochemical parameters and analyses of phenolic compounds were carried out in control, CT and ProCa grapes and wines and wine sensory was performed. Thinning treatments decreased crop yield, besides ProCa application reduced berry size, and berry weight. Color and phenolic composition of Grenache and Tempranillo wines in general were affected by thinning treatments, with an increase in anthocyanin, flavanol and flavonol concentrations. In sensory analysis, wines obtained from thinned vines presented higher values for several aromatic (e.g., white and yellow fruits, fresh flowers) and taste attributes (i.e., astringency, bitternes, persistence). CT and ProCa treatments resulted in an improvement in wine quality. In general, similar results in phenolic composition, sensory properties and quality of wines were obtained by manual and chemical cluster thinning. ProCa as a growth regulator may be an option for a quality vitiviniculture.