The monomeric, oligomeric, and polymeric flavan-3-ol composition of wines, grape seeds, and skins from Vitis vinifera L. cv. Graciano, Tempranillo, and Cabernet Sauvignon has been studied using (1) fractionation by polyamide column chromatography followed by HPLC/ESI-MS analysis, (2) fractionation on C(18) Sep-Pak cartridges followed by reaction with vanillin and acid-catalyzed degradation in the presence of toluene-alpha-thiol (thiolysis). The content of monomers ((+)-catechin and (-)-epicatechin), procyanidin dimers (B3, B1, B4, and B2), trimers (T2 and C1), and dimer gallates (B2-3-O-gallate, B2-3'-O-gallate, and B1-3-O-gallate) ranged from 76.93 to 133.18 mg/L in wines, from 2.30 to 8.21 mg/g in grape seeds, and from 0.14 to 0.38 mg/g in grape skins. In wines, the polymeric fraction represented 77-84% of total flavan-3-ols and showed a mean degree of polymerization (mDP) value of 6.3-13.0. In grapes, the polymeric fraction represented 75-81% of total flavan-3-ols in seeds and 94-98% in skins and showed mDP values of 6.4-7.3 in seeds and 33.8-85.7 in skins. All the monomeric flavan-3-ols and oligomeric procyanidins found in wines were also present in seeds, although differences in their relative abundances were seen. The skin polymeric proanthocyanidins participated in the equilibration of the wine polymeric proanthocyanidin fraction, especially contributing to the polymer subunit composition and mDP.
The phenolic composition of skins and seeds from Vitis vinifera L. cv. Carménère and Cabernet Sauvignon grapes during ripening was evaluated by high-performance liquid chromatography-diode array detection and spectrophotometric analysis. As compared to Cabernet Sauvignon grape skins, Carménère grape skins presented higher contents of total anthocyanins, monomeric flavan-3-ols, and total flavonoids, a higher mean degree of polymerization, a higher percentage of galloylation, a higher average molecular weight of the flavanol fraction, and a higher color intensity. As compared to Cabernet Sauvignon grape seeds, Carménère grape seeds presented a lower content of monomeric flavan-3-ols, a higher mean degree of polymerization, a higher percentage of galloylation, a higher average molecular weight of the flavanol fraction, a lower content of (+)-catechin, and higher contents of (-)-epicatechin, epicatechin-3-O-gallate, gallic acid, and dimeric procyanidins esterified with gallic acid. Altogether, we conclude that Carménère grapes present a differential composition and evolution of phenolic compounds when compared to Cabernet Sauvignon grapes.
Interaction between anthocyanins (3-glucosides of cyanidin, peonidin and
malvidin), procyanidin
B2 (B2), and acetaldehyde and the formation of
new colored compounds was studied in model wine
solutions. The anthocyanin−procyanidin B2
condensation reaction showed first-order kinetics with
or without the presence of acetaldehyde, and the reaction rates were
calculated. In all the model
solutions containing anthocyanins, procyanidin B2, and
acetaldehyde, rapid color augmentation with
shifts toward violet were observed. Two principal new compounds
(thought to be trimers, linked at
different positions) were detectable by HPLC, and their spectral
properties were studied by diode-array spectroscopy. Malvidin 3-glucoside reacts more slowly than
cyanidin 3-glucoside and
peonidin-3 glucoside. Similar color changes were observed in model
solutions containing anthocyanins alone with acetaldehyde. Finally, we observed that the
degradation constant rates for each
anthocyanin increased in the following order: anthocyanins alone <
anthocyanins + B2 <
anthocyanins + acetaldehyde < anthocyanins + B2 +
acetaldehyde. Similar increasing order of
the reaction rates of procyanidin B2 was observed. In
both cases, the presence of acetaldehyde was
of major importance in accelerating the chemical transformation of
phenolic compounds, inducing
the formation of new products.
Keywords: Anthocyanins; procyanidin B2; acetaldehyde;
condensation reaction
Commercial oenological products containing mannoproteins have the purpose of preventing tartrate salts precipitation or achieving wines with a better mouth-feeling. The evaluation of the influence of three commercial mannoproteins on colour and tannin stability of three different red wines (two from Touriga Nacional and one from Alfrocheiro and Aragonês varieties) was studied. The evolution of colour through time was similar for all modalities, resulting in an increase of polymeric pigments and colour hue and a decrease of other parameters, suggesting that there was no influence of commercial mannoproteins on colour stability. The tannin profile evolution showed a possible stabilizing effect of one of the commercial products for tannins with an mDP between 8 and 14. It is possible that the commercial mannoproteins used in this work have some influence on the tannin aggregation evolution, contributing to the delay of tannin polymerisation in red wines.
<p style="text-align: justify;">A red wine was matured in contact with 4 g/L of oak wood chips from Portuguese (Quercus pyrenaica Willd.), French (Quercus petraea L.) and a mixture (50:50) of this two oak wood species, during 13 weeks, in order to evaluate the effects of these different oak wood chip species (specially Portuguese oak wood) on the phenolic composition evolution of the wine and in their sensory properties. In general, for the phenolic compounds studied, it wasn't possible to detect remarkable differences between the control wine (aged without oak wood chips) and the wines aged in contact with the two oak wood chips species used. However, for non-flavonoid phenols, the presence of oak wood chips contributed to an increase of these compounds in red wines. The influence of oak wood chips in anthocyanins evolution were similar for all wines, except for malvidin-3-glucoside, which decrease was more evident for the wine aged in contact with oak wood chips. The oak wood chips species and the chips concentration used in this study, didn't affect the proanthocyanidin contents in the wines during the time considered.</p><p style="text-align: justify;">Sensory results showed that, the wines aged in contact with Portuguese and French oak wood chips and the mixture of this two oak wood species, differed significantly from the control wine in several sensorial characteristics. The wines aged in contact with wood chips showed a higher punctuation values for intensity, toasted, wood and vanillin aroma, taste intensity and global appreciation. This positive effect was more evident for wines aged with Portuguese oak wood chips. Probably this results, suggest that the Portuguese oak wood samples species (Quercus pyrenaica Willd.) used could be considered suitable for barrel production because it has a positively effect in sensorial red wine attributes. Thus with this study we tried to contribute for understand the Portuguese oak wood role in red wine characteristics.</p>
The ellagitannins and ellagic acid from extracts of Portuguese oak wood chips (Quercus pyrenaica) used in cooperage from different origins (Gerês and Guarda forests) were analysed by HPLC. The results were compared with the ellagitannin content of wood chips obtained from American (Q. alba) and French (Q. petraea) oak. The influence of heat treatment and the coarseness of the grain on ellagitannins and ellagic acid were also studied. Five ellagitannins (vescalagin, castalagin, roburin D, roburin E and grandinin) and ellagic acid were quantified. Vescalagin and castalagin were the most abundant individual ellagitannins in all of the oak wood chips studied. Portuguese oak wood had the highest content of ellagitannins and ellagic acid, followed by the French and American oaks. The geographical origin of Portuguese oak and the coarseness of the grain of French oak affected the content of ellagitannins and ellagic acid. In general, the ellagitannin content decreased with the toasting process, while the ellagic acid content increased. The toasting process had the highest impact on ellagitannin composition in comparison to the other variables studied.
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