Classification of South African red and white wines according to grape variety based on the non-coloured phenolic content

The phenolic content of South African wines was investigated for the purpose of their classification according to variety or cultivar. Twenty-two phenolic compounds were quantified by liquid chromatography in 55 red wines of five varieties and in 38 white wines of three varieties. Data were compared to literature values reported for wines from across the globe. ANOVA was used to determine significant concentration differences between the different varieties. Further grouping of the data was investigated by principal component analysis and cluster analysis. Finally, linear discriminant analysis was used to derive classification functions for the effective recognition of red and white wine varieties which allowed 100.0% and 97.4% correct recognition of red and white wines, respectively.     

Phenolic characterisation of red wines from different grape varieties cultivated in Mendoza province (Argentina)

BACKGROUND: Knowledge of the chemical composition of wine and its association with the grape variety/cultivar is of paramount importance in oenology and a necessary tool for marketing. Phenolic compounds are very important quality parameters of wines because of their impact on colour, taste and health properties. The aim of the present work was to study and describe the non‐flavonoid and flavonoid composition of wines from the principal red grape varieties cultivated in Mendoza (Argentina). RESULTS: Sixty phenolic compounds, including phenolic acids/derivatives, stilbenes, anthocyanins, flavanols, flavonols and dihydroflavonols, were identified and quantified using high‐performance liquid chromatography with diode array detection coupled with electrospray ionisation mass spectrometry (HPLC‐DAD/ESI‐MS). Marked quantitative differences could be seen in the phenolic profile among varieties, especially in stilbenes, acylated anthocyanins and other flavonoids. CONCLUSION: The polyphenolic content of Malbec wines was higher compared with the other red varieties. Dihydroflavonols represent a significant finding from the chemotaxonomic point of view, especially for Malbec variety. This is the first report on the individual phenolic composition of red wines from Mendoza (Argentina) and suggests that anthocyanins, flavanols and phenolic acids exert a great influence on cultivar‐based differentiation. Copyright © 2011 Society of Chemical Industry     

Characterization of Polish Wines Produced from the Multispecies Hybrid and Vitis vinifera L. Grapes

Phenolic profile, antioxidant activity, and color parameters of Polish wines, produced from the multispecies hybrid and Vitis vinifera L. grapes were analyzed. A principal component analysis was applied, in order to differentiate the investigated wines in terms of content of phenolic compounds. The white wines turned out to be similar to each other in terms of color parameters and the results of principal component analysis, while the red wines strongly differed in this respect. However, the white wine produced from the multispecies hybrid grapes contained a higher level of phenolic acids and flavonoids, as compared to the white wines obtained from the hybrid cultivars. Out of the red wines, Rondo wine, produced from the multispecies hybrid grapevine was the richest in total phenolic and phenolic acids content. Caffeic acid and quercetin were the predominant phenolics in majority of the wines tested.     

Analysis of phenolic compounds in Spanish red wines by capillary zone electrophoresis

A simple technique for the routine capillary electrophoretic analysis of phenolic compounds in red wines from different Spanish regions, is described. Separation was achieved using a fused-silica capillary column with a borate buffer at pH 9.5, and UV detection at 280 nm. The compounds identified were: (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, syringic acid, vanillic acid, gallic acid, 3,4 dihydroxybenzoic acid, p-coumaric acid, caffeic acid and the hydroxycinnamic tartaric acid esterscis- andtrans-coumamyl tartaric acid andcis-caffeoyl tartaric acid. Different wines showed very similar electrophoretic profiles, but significant quantitative differences were observed.     

Indian Grape Wines: A Potential Source of Phenols,Polyphenols, and Antioxidants

Indian grape wines are analyzed for total phenolic content and antioxidant activity along with other parameters, such as pH, alcohol content, and reducing sugars. Concentration of polyphenols, like tannic acid, catechol, vanillin, caeffic acid, ferullic acid, and resveratrol, was quantified using reverse phase-high performance liquid chromatography and ultra high performance liquid chromatography. The red wines showed the highest concentration of phenolic content (6.5 ± 0.1 mg/ml) and antioxidant activity (84.60 ± 1%) as compared to white and port wines, while red wine R2 showed the highest radical scavenging activity among red wines and R4 showed the lowest total phenolic content. The white wine W3 showed less total phenolic content and antioxidant activity. Further, a positive correlation between phenolic content and antioxidant activity was observed.     

Phenolic compounds in a Spanish red wine aged in barrels made of Spanish,French and American oak wood

A red Rioja wine was aged in barrels made of Spanish oak wood for 21 months. The evolutions of colour percentage intensity, families of phenolic compounds and low molecular weight phenolic compounds were studied in these wines and compared with those of the same wine aged in barrels made of French and American oak. The analysis of chromatic parameters and total anthocyanins indicates that the wines aged in Spanish and French oak wood barrels have similar chromatic characteristics, but are significantly different to those of wines aged in barrels made of American oak wood, indicating a different degree of modification of the colour. The ageing process also had an important influence on the low molecular weight polyphenols composition of wine. The evolution of these components allowed the production of wines with different characteristics, in relation to the type of wood used in barrel making process. On the other hand, Spanish oak wood can be considered suitable for barrel production for quality wines, since a wine aged in barrels made of Spanish oak wood showed similar and intermediate characteristics to those of the same wine aged in French and American oak woods.     

Proanthocyanidin content,antioxidant capacity and scavenger activity of Portuguese sparkling wines (Bairrada Appellation of Origin)

BACKGROUND: The main object of the present study was to investigate the different proanthocyanidin fraction (monomeric, oligomeric and polymeric fraction) contents, antioxidant capacity and scavenger activity of the most important and representative commercial sparkling wines available in Bairrada Portuguese Appellation of Origin. RESULTS: The white commercial sparkling wines tested had much less total phenolic, proanthocyanidin content, antioxidant capacity and scavenger activity than the sparkling red wines. For all white and red sparkling wines the polymeric fraction of proanthocyanidins was the most abundant fraction quantified. The antioxidant capacity was positively correlated with the different proanthocyanidin fractions studied. However, in general, higher correlations between total polyphenols, different proanthocyanidin fractions and antioxidant capacity were found only for red sparkling wines. CONCLUSION: The results confirm that Portuguese sparkling wines from Bairrada Appellation of Origin are good sources of antioxidants when compared with other wines elaborated from other grapes varieties and from other regions. At same time, good linear correlations between the levels of each different proanthocyanidin fractions and total polyphenols with antioxidant capacity were found for the commercial sparkling wines analysed. Copyright © 2010 Society of Chemical Industry     

Polyphenolic compounds and antioxidant properties of selected China wines

Thirty-seven China wines, produced from different geographical origins, were examined in this study. The antioxidant activity of wines was measured by different analytical methods: oxygen radical absorbance capacity (ORAC), reducing power, 2,2-azino-di-(3-ethylbenzothialozine-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH·), hydroxyl radical-scavenger activity, superoxide radical-scavenger activity, lipid peroxidation and chelating capacity. Furthermore,total phenols, total flavonoids, total flavanols and total anthocyanins of wines were determined. As expected, the red wines had much higher phenolic content and antioxidant capacity than rosé wines or white wines. Among the red wines, Cabernet Sauvignon and Muscat Hamburg, respectively, represented the wines with the highest and lowest phenolic contents and antioxidant capacity. Among the white wines, Italian Riesling had the lowest phenolic content and antioxidant capacity. Taken together, a close relationship between phenolic contents and antioxidant capacity, for all wines, was observed.     

Chemometric investigation of the volatile content of young South African wines

The content of major volatiles of 334 wines of six different cultivars (Sauvignon Blanc, Chardonnay, Pinotage, Shiraz, Cabernet Sauvignon and Merlot) and vintage 2005 was used to investigate the aroma content of young South African wines. Wines were sourced from six different regions and various producers. Thirty-nine volatile components partially responsible for the flavour of wine were quantified. In order to investigate possible correlation between volatile content and grape variety and/or geographical origin, analysis of variance, factor analysis (FA), principal component analysis (PCA) and linear discriminant analysis (LDA) were used. Significant differences in the levels of certain volatiles were observed as a function of region and cultivar, with the latter factor proving to be more influential. A few volatile compounds were identified as potential predictors of the white wine cultivars. Prediction for red wine cultivars was poor, with the exception of Pinotage wines, for which three compounds (isoamyl acetate, isoamyl alcohol and ethyl octanoate) were identified as accurate predictors. The reasons for the importance of these three volatile compounds in distinguishing young Pinotage wines are discussed, and possible reasons for the unique levels in wines of this cultivar are highlighted.     

Classification of red and white wines by denomination of origin according to phenolic composition and colour characteristics and correlation with standard parameters

The two main phenolic compounds, namely anthocyanins and tannins, and some chromatic characteristics have been determined in 437 samples of red and white wines from northwest of Spain, which were commercialised in two consecutive years (2005 and 2006). The variation range for total polyphenol index (TPI) was 4.1–16.6 and 27.8–91.9 in white and red wines, respectively. Standard parameters were also investigated. The classification successful by Denominations of Origin was near 50% for both red and white wines. Statistical correlations among standard and colour parameters were established to find a simple methodology usually used in winery that permits to provide more complete information for the oenologist. So, a significant correlation was found for TPI or chromatic intensity and volume mass in red wines (0.547–0.583, P < 0.01), while tonality can be estimated from pH (0.601, P < 0.01). No lineal relationship was found in white wines.     

Free radical scavenging capacity of selected red,rosé and white wines

The free radical scavenging capacity of selected red, rosé and white Spanish wines from different grape varieties was determined by the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^·) method using a new methodology developed at our laboratory. The amount of sample necessary to decrease by 50% the initial DPPH^· concentration (EC₅₀), the time needed to reach the steady state at EC₅₀ concentration (T_EC50) and the antiradical efficiency (AE = 1/EC₅₀T_EC50) were determined in the wine samples. Some differences between rosé wines made with Garnacha and Tempranillo grape varieties were observed in the UV‐vis spectra and in the free radical scavenging parameters, those from Garnacha variety having the highest antioxidant activity. The antiradical efficiency of the wines followed a decreasing order: red wines (22.44 × 10⁻⁶) > rosé wines (4.90 × 10⁻⁶) > white wines (1.88 × 10⁻⁶). There was a correlation between antiradical efficiency and total polyphenol (TP): AE = −3.33135 + 0.0180535TP; the correlation coefficient was r = 0.951454. © 1999 Society of Chemical Industry     

Polyphenolic composition of Spanish red wines made from Spanish Vitis vinifera L. red grape varieties in danger of extinction

Phenolic composition, chromatic characteristics, and antioxidant activity of young wines made from three minority red grape varieties (Moravia Dulce, Rojal and Tortosí) cultivated in the Spanish region of Castilla-La Mancha were studied over two vintages. Phenolic contents were affected by both grape variety and vintage, whereas phenolic profiles were mainly affected by grape cultivar, thus allowing their differentiation The anthocyanin profiles of Moravia Dulce and Tortosí wines were dominated by malvidin 3-glucoside, whereas peonidin 3-glucoside was in Rojal wines. The flavonol profile of Rojal and, in a lesser extent, Tortosí wines were dominated by B-ring di-substituted flavonols (mainly quercetin-type flavonols). In contrast, B-ring tri-substituted flavonols (mainly myricetin-type) predominated in Moravia Dulce wines. All studied wines had high quantities of total resveratrol, especially Rojal and Moravia Dulce wines, although they mainly occurred as cis-isomers. Rojal wines always appeared as the most different single-cultivar wines in all parameters in this study, being characterized by the lowest content of almost all families of phenolic compounds. With regard to the colour characteristics, all the studied wines had normal values to be considered young red wines except for Rojal wines, which should be considered as rosé wines. Finally, all wines showed remarkable antioxidant activity, closely connected with their phenolic content. The results suggest that Moravia Dulce and Tortosí grape cultivars could be appropriate raw materials for the elaboration of quality young red wines, whereas Rojal grapes could be for rosé wines.     

Monitoring of chemical parameters of oxygen-treated musts during alcoholic fermentation and subsequent bottle storage of the resulting wines

The effect of hyper-oxygenation of Airén white wines on color characteristics, phenolic composition, and volatile profile has been evaluated in different processing steps, not previously reported in conjunction: musts, musts during the alcoholic fermentation, resulting young wines and after 1 year of bottle storage. Hyper-oxygenation treatment achieved a positive effect on color stabilization by means of significantly lower contents of most important phenolic compound families (hydroxycinnamic acid derivatives, benzoic acids, flavonols, and flavan-3-ols) in oxygen-treated musts in fermentation, young wines, and one-year-stored white wines. Therefore, browning was avoided in wines elaborated from hyper-oxygenated musts and their values of a* (green–red component of color) were maintained, in contrast to what occurred in control wines. With regard to volatile profile, the concentration of the majority of individual volatile compounds was significantly higher in wines derived from hyper-oxygenated musts, even after 1 year of bottle storage, especially those derived from alcoholic fermentation (alcohols: 2-methyl-1-butanol and 3-methyl-1-butanol, polar esters: ethyl lactate and ethyl glutarate, C₆ alcohols: 3-methyl-1-pentanol, and acetates: 2-phenylethyl acetate). This study enhances knowledge regarding the effects of hyper-oxygenation process during and after alcoholic fermentation and 1 year of bottle aging, especially as there is scarce literature available on the subject.     

Classification and characterisation of Spanish red wines according to their appellation of origin based on chromatographic profiles and chemometric data analysis

Chromatographic profiles of wines have been used as a fingerprint for the discrimination of Spanish wines based on oenological practices. In order to extract information of different families of phenolic compounds, profiles of different UV-vis absorption wavelengths (280, 310, 370 and 520nm) and fluorescence (ex=260nm; em=360nm) were analysed. A total of thirteen phenolic compounds which allowed the discrimination of wines of three different Spanish appellations (Penedes, Rioja and Ribera del Duero) were selected by means of principal component analysis (PCA). Afterwards, these compounds were used to build partial least squares discriminant analysis (PLS1-DA and PLS2-DA) models which allowed the discrimination of wines according to their appellation with classification rates for independent test sets higher than 96% and 93% for PLS1-DA and PLS2-DA models respectively. Finally, characteristic compounds of each appellation were tentatively identified by means of liquid chromatography-mass spectrometry (LC-MS) analysis. Thus, ten out of thirteen compounds (i.e., gallic acid for Penedes, trans-coumaroyltartaric and trans-caffeoyltartaric acids for Rioja and myricetin for Ribera del Duero wines) have been proposed.     

Relationship between Sensory Perception,Volatile and Phenolic Components in Commercial Spanish Red Wines from Different Regions

Polyphenols are an important fraction of the non-volatile components in the red wine matrix, and they are influenced in quantity and composition at all stages from the grape growing conditions until the time the wine is consumed. Evidence of their interaction with volatiles has been found, and this should affect wine flavour. A range of 12 commercial Spanish red wines from different regions and ages was analysed for their sensory properties, volatile composition in solution and headspace, and their non-volatile phenolic components. Maturation was the most important effect on sensory perception, while the chemical data showed also individual differences between the wines and their regions of production. Headspace volatiles and the phenolic fraction showed better correlations with the sensory perception, but volatiles in solution did not give a good prediction, though there were changes related to maturation. Some flavour components showed changes in their volatile behaviour in the matured wines. This supports the hypothesis that changes in the behaviour of the volatile fraction are related to the evolution of phenolic compounds.     

Relationship between the antioxidant properties and the phenolic and flavonoid content in traditional balsamic vinegar

The antioxidant properties of traditional balsamic vinegar as regards its phenolic and flavonoid content comparing it to selected vinegars and red wines have been investigated. The polyphenols were separated from interfering compounds utilizing C18 columns. The polyphenolic content was determined utilizing both Folin–Ciocalteu and peroxidase assays. The antioxidant capacity was quantified using both ABTS and FRAP assays. The results show that traditional balsamic vinegar has lower antioxidant activity and phenolic and flavonoid content than Nero d’Avola but higher than the other tested products. The antioxidant capacity of wines and vinegars is highly correlated with their phenolic content, measured by peroxidase assay and it is also highly correlated with their flavonoid content while in traditional balsamic vinegar and balsamic vinegar this correlation diminishes. The study describes a simple and fast method of separating from other compounds and of measuring polyphenols in the analysis of red wines and vinegars with complex composition such as traditional balsamic vinegar.     

The Effect of Path Length on the Measurement Accuracies of Wine Chemical Parameters by UV,Visible, and Near-Infrared Spectroscopy

The use of spectral measurements using either UV, visible (VIS), or near-infrared (NIR) spectroscopy to characterize wines or to predict wine chemical composition has been extensively reported. However, little is known about the effect of path length on the UV, VIS, and NIR spectrum of wine and the subsequent effect on the performance of calibrations used to measure chemical composition. Several parameters influence the spectra of organic molecules in the NIR region, with path length and temperature being one of the most important factors affecting the intensity of the absorptions. In this study, the effect of path length on the standard error of UV, VIS, and NIR calibration models to predict phenolic compounds was evaluated. Nineteen red and 13 white wines were analyzed in the UV, VIS, and NIR regions (200–2500 nm) in transmission mode using two effective path lengths 0.1 and 1 mm. Principal component analysis (PCA) and partial least squares (PLS) regression models were developed using full cross validation (leave-one-out). These models were used to interpret the spectra and to develop calibrations for phenolic compounds. These results indicated that path length has an effect on the standard error of cross validation (SECV) absolute values obtained for the PLS calibration models used to predict phenolic compounds in both red and white wines. However, no statistically significant differences were observed (p > 0.05). The practical implication of this study was that the path length of scanning for wines has an effect on the calibration accuracies; however, they are non-statistically different. Main differences were observed in the PCA score plot. Overall, well-defined protocols need to be defined for routine use of these methods in research and by the industry.     

Determination of flavan-3-ols and trans-resveratrol in grapes and wine using HPLC with fluorescence detection

Concentrations of trans-resveratrol, catechin and epicatechin were analyzed in musts and wines produced from seven red and four white grape cultivars from various wine growing regions of Turkey. Phenolics were quantified using an HPLC method optimized for the separation of wine phenolics. Wine samples contained higher phenolics levels than the corresponding musts. With the exception of Semillion, white wines and musts contained lower concentrations of phenolics than red wines and musts. However, the white cultivar Semillion had the highest concentrations of catechin and epicatechin among all wine and must samples. Semillion wine catechin and epicatechin were 13.7 and 11.8 mg/L, respectively. The highest level of trans-resveratrol among the white cultivars was found in Narince wine (1.93 mg/L). Within the red wine and must cultivars, Bo?azkere, Öküzgozü, and Cabernet contained the highest concentrations of flavan-3-ols and trans-resveratrol. Catechin was the major phenolic in all wines and most musts. Epicatechin was the major phenolic in 6 of the 11 must samples, but none of the wine samples. trans-Resveratrol was generally found in lowest concentrations in both wines and musts.     

Astringency,bitterness and color changes in dry red wines before and during oak barrel aging: An updated phenolic perspective review

To understand effects of using oak barrels on the astringency, bitterness and color of dry red wines, phenolic reactions in wines before and after barrel aging are reviewed in this paper, which has been divided into three sections. The first section includes an introduction to chemical reactivities of grape-derived phenolic compounds, a summary of the phenolic reactions that occur in dry red wines before barrel aging, and a discussion of the effects of these reactions on wine astringency, bitterness and color. The second section introduces barrel types that determine the oak barrel constituents in wines (primarily oak aldehydes and ellagitannins) and presents reactions between the oak constituents and grape-derived phenolic compounds that may modulate wine astringency, bitterness and color. The final section illustrates the chemical differences between basic oxidation and over-oxidation in wines, discusses oxygen consumption kinetics in wines during barrel aging by comparing different oxygen consumption kinetics observed previously by others, and speculates on the possible preliminary phenolic reactions that occur in dry red wines during oak barrel aging that soften tannins and stabilize pigments via basic oxidation. Additionally, sulfur dioxide (SO₂) addition during barrel aging and suitability of adopting oak barrels for aging wines are briefly discussed.