Esteban García-Romero

Red-Color Related Phenolic Composition of Garnacha Tintorera (Vitis vinifera L.) Grapes and Red Wines

Garnacha Tintorera (also known as Alicante Bouschet) is one of the few V. vinifera grape cultivars with red-colored berry flesh. The study of the phenolic composition of both berry flesh and skin of Garnacha Tintorera grapes shows interesting findings. Anthocyanins were asymmetrically distributed within grape flesh and skins. Malvidin derivatives dominated in skin, followed by peonidin-type anthocyanins; in contrast, the flesh almost exclusively contained peonidin 3-glucoside. In addition, LC-UV-vis and LC-MS evidence suggest the presence of small amounts of peonidin 3,5-diglucoside and a second peonidin dihexoside derivative, and, very likely, the first report of the occurrence of pelargonidin 3-glucoside and its acetyl and p-coumaroyl derivatives in V. vinifera grapes. Flavonols also occurred in the flesh of Garnacha Tintorera grapes, but its flavonol profile showed lower contribution of trisubstituted flavonoid structures (myricetin, laricitrin, and syringetin) when compared to that of skin. The skin of Garnacha Tintorera grapes contained hydroxycinnamic acids in higher amounts than in flesh, caftaric acid being the main derivative found, and coutaric acid accounting for its highest proportion in the skin. The phenolic composition of the whole grape berries reflected the average of the differences described for the two aforementioned berry parts, and subsequently, the red wines made from these grapes had a phenolic composition closer to that shown by the whole berries. The formation of anthocyanin-derived pigments in Garnacha Tintorera red wines makes necessary the use of LC-MS for detecting the minor pelargonidin-based anthocyanins and peonidin dihexoside, which could be suggested as chemical markers for cultivar authentication of this grape cultivar and its wines.

Phenolic composition of the edible parts (flesh and skin) of Bordô grape (Vitis labrusca) using HPLC-DAD-ESI-MS/MS.

The aim of this study was the detailed characterization of the phenolic composition and the determination of the antioxidant activity of the Bordô grape (Vitis labrusca) cultivated in South Brazil. The edible parts of Bordô grapes (flesh and skin) contained 1130 mg/kg of total phenolic compounds (as gallic acid), mainly located in the skins. Anthocyanin content in the skins was high, largely as 3,5-diglucosides (1359 mg/kg, as malvidin 3,5-diglucoside). Total flavonols accounted for 154 μmol/kg, mainly located in the skins and with myricetin 3-glucoside as the principal flavonol in both grape parts. Very low amounts of flavan-3-ol monomers and dimers and low amounts of polymeric proanthocyanidins, with a composition similar to that reported for V. vinifera grape varieties, were found in Bordô grape skins. Hydroxycinnamic acid derivatives mainly derived from caffeic acid and were found in the skins in high amounts, ten times higher than in the flesh (total amount: 483 μmol/kg). Finally, the Bordô grape cultivar can be considered a high resveratrol producer (10.91 mg/kg) and also exhibited a high value of total antioxidant capacity (37.6 ± 1.0 mmol/kg, as Trolox).

Phenolic Composition of the Brazilian Seedless Table Grape Varieties BRS Clara and BRS Morena

The detailed phenolic composition (anthocyanins, flavonols, hydroxycinnamic acid derivatives, stilbenes, and flavan-3-ols) in the skin and flesh of the new BRS Clara and BRS Morena seedless table grapes has been studied using HPLC-DAD-ESI-MS/MS. The two grapes, especially BRS Morena, contained high amounts of phenolic compounds, mainly located in their skins and qualitatively not different from those found in Vitis vinifera grapes. In addition, BRS Morena (a teinturier variety) showed qualitatively different phenolic compositions in its skin and flesh, mainly affecting the anthocyanin and flavonol profiles. Consistent with high phenolic contents, high antioxidant capacity values were registered for both grape varieties, especially for BRS Morena. Proanthocyanidins and hydroxycinnamoyl-tartaric acids were the major phenolic compounds found in BRS Clara and were also important in BRS Morena, although anthocyanins were the main phenolic compounds in the latter case. These results suggest that the entire grapes, including the skin, may potentially possess properties that are beneficial to human health. In this context, the BRS Morena grape can be considered as a high resveratrol producer.

Storage stability of phenolic compounds in powdered BRS Violeta grape juice microencapsulated with protein and maltodextrin blends.

The stabilities of the phenolic compounds, antioxidant activity and colour parameters of microencapsulated powdered BRS Violeta red grape juice were evaluated throughout storage at 5, 25 and 35°C for up to 150days. Different soy protein (S) or whey protein (W) blends with maltodextrin (M) were used as carrier agents, added at diverse concentrations and proportions. The treatment combining S and M with the highest carrier agent concentration (1SM) preserved almost all the anthocyanins. Except for 1SM, the proportion of p-coumaroylated anthocyanins increased during storage, and the flavonol content of the 1SM powder decreased after 150days. The hydroxycinnamate content decreased for all treatments, independent of storage temperature, and flavan-3-ols were lost at 35°C. The time and temperature did not influence the antioxidant activity of the powder or the colour of the reconstituted grape juice after 150days.

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.

Structure elucidation of peonidin 3,7-O-β-diglucoside isolated from Garnacha Tintorera (Vitis vinifera L.) grapes.

Red wines made from Garnacha Tintorera grapes (also known as Alicante Bouschet and one of the few so-called teinturier Vitis vinifera grape cultivars, because its berry flesh is also red-colored) are usually blended with other red wines as a natural way for enhancing the color intensity of red wines. The phenolic composition of Garnacha Tintorera grapes showed already described interesting features such as the occurrence of unusual anthocyanins (pelargonidin-based anthocyanins and a peonidin dihexoside) that had not been previously described in V. vinifera cultivars. The isolation and further structure elucidation (GC-MS analysis of sugar moieties, UV-vis, LC-MS(n), and (1)H and (13)C NMR spectroscopic data) have allowed the identification of the aforementioned peonidin dihexoside as peonidin 3,7-β-O-diglucoside. This peonidin derivative, in combination with the previously reported pelargonidin-type anthocyanins, can be suggested as a suitable chemical marker for this singular V. vinifera grape cultivar and the wines made totally or partially from this grape cultivar.

Influence of the botanical origin and toasting level on the ellagitannin content of wines aged in new and used oak barrels

The influence of the botanical origin (French oak: Quercus petraea and American oak: Quercus alba) and different toasting levels (light, medium and heavy) on the ellagitannin content of wines aged in oak barrels has been studied. This took place in two consecutive vintages in order to study what happens after the barrels have been already used for one year with another wine. This study was carried out with two red wines (Cabernet Sauvignon) and with two decolored white wines (Macabeo) from vintages 2012 and 2013 in order to work with a simpler matrix which facilitates chemical analysis. The results show that the botanical origin, toasting level and the number of times that the barrels have been used exert a major influence on the final ellagitannin concentration. In general, the behavior of all the individual ellagitannins was very similar to that described for the total ellagitannins. Briefly, the levels of total ellagitannins concentration in the decolored white wine aged for 12months in new French barrels ranged between 31.2mg/L in the lightly toasted and 4.7mg/L in the heavy toasted. In contrast, these levels were quite lower in American new barrels ranging between 3.6mg/L and 0.9mg/L. Finally, the total ellagitannin concentration decreased an average of 63% in the wines aged in the one year used barrels.

Oxygen consumption rates by different oenological tannins in a model wine solution

The kinetics of oxygen consumption by different oenological tannins were measured in a model wine solution using the non-invasive method based on luminiscence. The results indicate that the oxygen consumption rate follows second-order kinetics depending on tannin and oxygen concentrations. They also confirm that the oxygen consumption rate is influenced by temperature in accordance with Arrhenius law. The indications are that ellagitannins are the fastest oxygen consumers of the different oenological tannins, followed in decreasing order by quebracho tannins, skin tannins, seed tannins and finally gallotannins. This methodology can therefore be proposed as an index for determining the effectiveness of different commercial tannins in protecting wines against oxidation.

Influence of Grape Seeds and Stems on Wine Composition and Astringency

The aim of this paper is to study the real influence of seeds and stems on wine composition, astringency, and bitterness. A decolored grape juice and a grape juice macerated for 4 days from the same Cabernet Sauvignon grapes were fermented with or without supplementation with 100% seeds, 300% seeds, or 100% stems. Once alcoholic fermentation had finished, the wines were analyzed and tasted. The presence of seeds and stems increased the concentration of flavan-3-ol monomers with respect to the controls. However, the seeds mainly released (+)-catechin and (-)-epicatechin, whereas the stems mainly released (+)-catechin and (+)-gallocatechin. The seeds and stems also released proanthocyanidins; those from seeds have a lower mDP and a high percentage of galloylation, whereas those from stems have a higher mDP and a relatively high percentage of prodelphinidins. The presence of seeds and stems brought about a slight but significant increase in pH and lowered titratable acidity and ethanol content. The presence of seeds boosted color intensity, whereas stems had the opposite effect. Finally, both seeds and stems increased wine astringency and bitterness.

Pre-drying and submerged cap winemaking: Effects on polyphenolic compounds and sensory descriptors. Part II: BRS Carmem and Bordô (Vitis labrusca L.)

Brazilian wine production is dominated by the use of American grape cultivars (Vitis labrusca L.) and their hybrids. In this context, this study analyzed the phenolic composition and sensory profile of Bordô and BRS Carmem red wines elaborated from traditional and two alternative winemaking technologies: grape pre-drying and submerged cap of chaptalized musts. Anthocyanins and pyranoanthocyanins apparently seemed to be affected by the thermal process (60°C), causing their degradation. In addition, the decrease of the concentration of these compounds could be suggested as a result of possible oxidation and hydrolysis reactions of anthocyanin 3-glucosides. Stilbenes were also affected by thermal degradation; however, flavan-3-ols and HCAD seemed to be less affected by the drying process. Submerged cap winemaking resulted in an increase of the anthocyanin and pyranoanthocyanin compounds due to the constant contact between the must and pomace during the alcoholic fermentation. The antioxidant capacity seemed not to be affected by thermal degradation, since the products of Maillard reaction also present antioxidant properties. Pre-dried wines were described as structured due to their higher flavan-3-ols content, and with high color intensity probably due to the formation of Maillard reaction products. The submerged cap wines presented an intense violet hue due to their high anthocyanin derivative concentrations and showed strong correlation with all other classes of the phenolic compounds.