Comparison between the phenolic composition of Petit Verdot wines elaborated at different maceration/fermentation temperatures

The Impact of Fermentation Temperature and Cap Management on Selected Volatile Compounds and Temporal Sensory Characteristics of Grenache Wines from the Central Coast of California

Grenache wines from the Central Coast of California were subjected to different alcoholic fermentation temperature regimes (Cold, Cold/Hot, Hot) and cap management protocols, namely, punch down (PD), or no punch down (No PD), to determine the effect of these practices on the color, aroma, and the retronasal and mouthfeel sensory characteristics of the resulting wines. Descriptive analysis (n = 8, line scale rating 0-15) results indicated that the combination of a hot fermentation temperature and no punch downs led to a significantly higher intensity in perceived color saturation (7.89) and purple hue (8.62). A two-way analysis of variance (ANOVA) showed that cap management was significantly more impactful on the perception of orthonasal aromas than fermentation temperature. The reduction aroma was significantly higher in No PD wines (5.02) compared to PD wines (3.50), while rose and hot aromas had significantly higher intensity perception for PD wines (5.18, 6.80) than for No PD wines (6.80, 6.14). Conversely, analysis of selected volatile compounds indicated that fermentation temperature was more impactful than cap management regime. Cold/Hot wines had higher concentrations of important esters such as ethyl hexanoate (650 µg/L) and isoamyl acetate (992 µg/L). Cold wines had a higher concentration of β-damascenone (0.719 µg/L). TCATA evaluation (n = 8) indicated that Cold/Hot PD wines had a significantly higher citation proportion of fruit flavor (1.0) and velvet astringency perception (0.80) without significant reduction flavors. Finally, the present study represents a contribution with the main volatile compounds (e.g., β-damascenone and esters in the Cold and Cold/Hot fermented wines, respectively; hexanol in PD wines, which may be potentially responsible for a hot mouthfeel), and sensory characteristics (red fruit, tropical fruit, white pepper, and rose) of Grenache wines grown in the Mediterranean climate of the Central Coast of California.

Different approaches to enhance resveratrol content in wine

Resveratrol is a polyphenol with antioxidant properties and possible beneficial effects on human health. Grapes, peanuts, berries, cacao beans and red wine contain resveratrol. Resveratrol attracts attention due to its bioactive properties, however, the concentration of this compound is not high in grape and wine. Therefore, different studies have been carried out to increase resveratrol level in these products. Several factors such as the grapevine variety, the climatic conditions and the viticultural practices used to create stress on the vine affect the level of resveratrol. Winemaking technologies applied during pre-fermentation, fermentation and post–fermentation stages could also have an effect on the concentration of this stilbene. In addition, recent studies have evaluated biotechnological approaches through the use of different bacteria and yeast strains to produce wine with increased resveratrol content. In this review, the most important factors contributing to increase the resveratrol concentration in grapes and wines are examined. Besides, analytical methods to determine resveratrol content in wine are addressed.

Identification of Tentative Traceability Markers with Direct Implications in Polyphenol Fingerprinting of Red Wines: Application of LC-MS and Chemometrics Methods

This study investigated the potential of using the changes in polyphenol composition of red wine to enable a more comprehensive chemometric differentiation and suitable identification of authentication markers. Based on high performance liquid chromatography-mass spectrometry (HPLC-MS) data collected from Feteasca Neagra, Merlot, and Cabernet Sauvignon finished wines, phenolic profiles of relevant classes were investigated immediately after vinification (Stage 1), after three months (Stage 2) and six months (Stage 3) of storage, respectively. The data were subjected to multivariate analysis, and resulted in an initial vintage differentiation by principal component analysis (PCA), and variety grouping by canonical discriminant analysis (CDA). Based on polyphenol common biosynthesis route and on the PCA correlation matrix, additional descriptors were investigated. We observed that the inclusion of specific compositional ratios into the data matrix allowed for improved sample differentiation. We obtained simultaneous discrimination according to the considered oenological factors (variety, vintage, and geographical origin) as well as the respective clustering applied during the storage period. Subsequently, further discriminatory investigations to assign wine samples to their corresponding classes relied on partial least squares-discriminant analysis (PLS-DA); the classification models confirmed the clustering initially obtained by PCA. The benefits of the presented fingerprinting approach might justify its selection and warrant its potential as an applicable tool with improved authentication capabilities in red wines.

Acetylation of Malvidin-3-O-glucoside Impedes Intermolecular Copigmentation: Experimental and Theoretical Investigations

Malvidin-3-O-(6-O-acetyl)-glucoside is usually the most abundant acylated anthocyanin in red wines. In this work, intermolecular copigmentation of malvidin-3-O-(6-O-acetyl)-glucoside and malvidin-3-O-glucoside with three phenolic copigments was carried out in model wine solutions, and the influence of the acetylation group was evaluated emphatically using experimental and theoretical approaches. This study found that there was no distinct coloring difference in the two anthocyanins themselves; however, the hyperchromic effects were smaller in malvidin-3-O-(6-O-acetyl)-glucoside solutions with the existence of insufficient copigments. Thermodynamic analysis confirmed that malvidin-3-O-(6-O-acetyl)-glucoside showed weaker affinity (smaller K values) toward the three copigments compared with its non-acylated form. Theoretical analysis also indicated that the existence of the acetylation group changed the spatial conformations and non-covalent interactions (hydrogen bonds and van der Waals forces) of the copigmentation complexes, which might be due to the potential steric hindrance effect. In conclusion, the results revealed that the acetylation group on anthocyanin glycosyl could impede intermolecular copigmentation.

Cardioprotective effect of red wine and grape pomace

Several studies have related moderate consumption of red wine with prevention of cardiovascular diseases (CVD). According to epidemiological studies, those regions with high consumption of red wine and a Mediterranean diet show a low prevalence of CVD. Such an effect has been attributed to phenolic compounds present in red wines. On the other hand, by-products obtained during winemaking are also a significant source of phenolic compounds but have been otherwise overlooked. The cardioprotective effect of red wine and its byproducts is related to their ability to prevent platelet aggregation, modify the lipid profile, and promote vasorelaxation. Phenolic content and profile seem to play an important role in these beneficial effects. Inhibition of platelet aggregation is dose-dependent and more efficient against ADP. The antioxidant capacity of phenolic compounds from red wine and its by-products, is involved in preventing the generation of ROS and the modification of the lipid profile, to prevent LDL oxidation. Phenolic compounds can also, modulate the activity of specific enzymes to promote NO production and vasorelaxation. Specific phenolic compounds like resveratrol are related to promote NO, and quercetin to inhibit platelet aggregation. Nevertheless, concentration that causes those effects is far from that in red wines. Synergic and additive effects of a mix of phenolic compounds could explain the cardioprotective effects of red wine and its byproducts.

Influence of grape seeds on wine composition and astringency of Tempranillo, Garnacha, Merlot and Cabernet Sauvignon wines

BACKGROUND

The aim of this work was to study the influence of grape berry morphology, especially the seed weight percentage, on the tannin concentration and astringency of red wine. Clusters of Tempranillo, Garnacha, Merlot, and Cabernet Sauvignon were characterized and their seeds were extracted and macerated in a model wine solution. In parallel, we elaborated three types of wines of each cultivar. One wine was made with only grape juice, one wine was made adding the appropriate proportion of seeds to the grape juice, and the last wine was elaborated with the complete destemmed and crushed berries.

RESULTS

Merlot and Cabernet Sauvignon grapes, which have higher percentage of seed weight with respect to the berry weight than Tempranillo and Garnacha grapes originated wines with higher tannin concentration and astringency than Tempranillo and Garnacha wines.

CONCLUSION

The main conclusion of this study is that the seed weight percentage with respect to the berry weight is one of the main determinants of the final tannin concentration and astringency of red wines.