Tannat Wines Research Articles

Social Desirability Bias in Contingent Valuation Surveys Administered Through In-Person Interviews

The aim of this study was to determine by HPLC-DAD-MS the pigment profiles and the different anthocyanin-derived pigment formation in four monovarietal young red wines produced in Uruguay from different grape varieties (Caladoc, Marselan, Marzemino, and Cheveñasco) and compare them to that of a young <i>Vitis vinifera</i> cv. Tannat wine produced in the same vintage. In quantitative terms, Tannat wine had the highest total pigment content whereas Cheveñasco had the lowest. Results showed differences not only in anthocyanin composition but also in the chemical nature of the major anthocyanin-derived pigments present in each wine. Tannat had the lowest content in derived pigments, vitisin A being the most representative. Caladoc and Marselan were characterized by the highest percentages of malvidin-3-glucoside and its acyl derivatives. The 4-vinylphenol derivative of malvidin-3-glucoside was the major pyranoanthocyanin in both wines, along with vitisin A in Caladoc and vitisin B in Marselan. The major anthocyanin-derived pigments of Marzemino were B-type vitisins. Marzemino also contained anthocyanin-flavanol acetaldehyde-mediated condensation products, which might indicate higher levels of acetaldehyde in this wine than in the others. Cheveñasco had the highest percentage of derived pigments, with the 4-vinylphenol derivative of malvidin-3-glucoside the most representative and the second most abundant compound after malvidin-3-glucoside.

Aroma composition of Vitis vinifera Cv. tannat: the typical red wine from Uruguay.

The free volatiles, as well as those released from the glycosidically bound forms by enzyme hydrolysis, have been analyzed to chracterize young Tannat wines from two successive vintages. The Tannat wine showed some aroma profile peculiarities detected in the free forms but, above all, in the bound fraction for the level and profile of the norisoprenoidic fraction. Among the free volatile compunds, a rather low content of C(6) alcohols with a prevalence of cis-3-hexen-1-ol on the trans form and sometimes a remarkable level of trans-2-hexen-1-ol seem to be typical for the variety. C(13)-norisoprenoidic and monoterpenic volatiles made up approximately 42% of the total level of the volatiles observed in the glycosidase enzyme-released fraction. The other volatiles were C(6) alcohols (6%) and benzenoid compounds (51%). The dominating monoterpene alcohols were the cis and trans isomers of 3,7-dimethyl-1,6-octadiene-3,8-diol (8-hydroxylinalool). The C(13)-norisoprenoid pattern was composed by 3-hydroxy-beta-damascone, 3-oxo-alpha-ionol, vomifoliol, 4-oxo-beta-ionol, 3-oxo-7,8-dihydro-alpha-ionol, 4-oxo-7,8-dihydro-beta-ionol, grasshopper ketone, and 7,8-dihydrovomifoliol.

Effect of beta-glycosidase activity of Oenococcus oeni on the glycosylated flavor precursors of Tannat wine during malolactic fermentation.

Under traditional wine-making conditions, this work examines the beta-glycosidic activity of Oenococcus oeni on glycosylated aroma compounds of Tannat wines during malolactic fermentation (MLF) by comparing the changes on selected aglycones liberated. MLF diminished the content of all the glycosylated compounds. The level of the free aroma components was slightly modified by the action of the malolactic fermentation so that the cleavage of the glycosidic linkage by the beta-glycosidic activity of O. oeni did not appear to increase significatively the aglycone contents. The consequences of further chemical rearrangements of the algycones under wine conditions were explored using synthesized glycoconjugates on synthetic medium. Bacteria could also be responsible for the cleavage of aroma glycosylated compounds, being the aglycone adsorbed on polysaccharides or peptidoglycans and was released into the external medium. This hypothesis was studied through the evaluation of a stable arrangement of aroma compounds with polysaccharides produced by lactic acid bacteria. A possible retaining of free-made aroma compounds into the whole cells of O. oeni was also investigated through cell culture analysis. Through the results obtained, we assume stable linkage of aroma compounds with bacterial polysaccharides.

Anthocyanic Composition of Tannat, Cabernet Sauvignon and Merlot Young Red Wines from Uruguay

The anthocyanic composition of the 1996 and 1997 harvests of Merlot, Cabernet Sauvignon and Tannat red wines from Uruguay was studied through the determination of their delphinidin, cyanidin, petunidin, peonidin and malvidin glucoside content, together with the corresponding acyl derivatives. The anthocyanic profiles of each variety showed significant differences, which may be used in their classification. Wine distribution according to variety was verified through the application of discriminative analysis. The most important anthocyanins in varietal differentiation were the petunidin and malvidin glucosides, together with the acetyl esters of the petunidin, peonidin and malvidin glucosides, indicating the importance of the methoxylation for varietal differentiation. The total anthocyanin average content and most of the individual anthocyanins analysed were higher in the Tannat wines. The concentrations of delphinidin, petunidin and their derivatives apparently define the anthocyanic profiles of the Tannat wines as compared to the Merlot and Cabernet Sauvignon wines of Uruguay.

Effect of malolactic fermentation on the aroma properties of Tannat wine

Descriptive sensory profiles of Uruguayan Tannat wines following malolactic fermentation (MLF) with Oenococcus oeni were compared with control wines where MLF was prevented. MLF led to a significant decrease (P < 0.05) in secondary descriptors such as ‘berry fruit’ and ‘fresh vegetative’, as well as a decrease in related tertiary descriptors such as ‘blackcurrant’, ‘apricot’, ‘cut green grass’ and ‘green pepper’. The main differences in the chemical composition of Tannat wine aromas following MLF were (1) an increase of the lactates (mainly ethyl lactate) over the sensory threshold; (2) a significant decrease in ethyl esters and acetates, depending on the bacteria strain utilised (the most significant change was found in hexyl acetate), and (3) a small increase of 4-vinylguaiacol and 4-vinylphenol with one of the MLF strains (this change was below the threshold of human perception). We also observed an increase of compounds related to α-ketoglutarate metabolism, namely: ethyl 4-hidroxibutanoate and γ-butyro-lactone. Differences in chemical composition due to MLF are discussed in relation to variation in sensory profiles.