The Study of Phenolic Compounds as Natural Antioxidants in Wine

Plant phenolics present in fruit and vegetables, and that are particularly rich in red wine, have received considerable attention because of their potential antioxidant activity. Human consumption of antioxidants has many alleged health benefits, including protection against cardiovascular diseases, and, most recently, cancer. Red wines contain a variety of polyphenolic antioxidants. Five samples of commercial red wines from Spain and four phenolic compounds of red wine: gallic acid, trans-resveratrol, quercetin and rutin, have been studied. The total phenolics content and the total antioxidant activity (TAA) of wines was determined. The total phenolic content, determined according to the Folin-Ciocalteu method, varied from 1800 to 2300?mg/L, expressed as gallic acid equivalents (GAE). The antioxidative effects of wine phenolics were determined using a system based on the inhibition by antioxidants of the absorbance of the radical cation. The relationship between antioxidant activity of phenolic compounds, as hydrogen donating free radical scavengers, and their chemical structures was studied. Furthermore, the total antioxidant activity of the wines investigated was well correlated with phenol content. Thus, the results confirm that red wine polyphenols are, in vitro, significant antioxidants.     

Flavonol composition of Australian red and white wines determined by high‐performance liquid chromatography

Background and Aims: Flavonols are present in Vitis vinifera L. wine grapes as glycosides and are found in wines in both their glycosidic and aglycone forms. Flavonols and their glycosides are important components in wine because of their impact on colour, taste and health properties. An assessment of the flavonols and flavonol glycosides present in a wide selection of Australian red and white wines (n = 121 and 44, respectively) was undertaken. Methods and Results: Analyses were performed using HPLC, with compound identification being aided by HPLC‐MS. In the red wines, quercetin and myricetin dominated the flavonol profile, and quercetin‐3‐glucuronide was by far the most abundant glycoside present. White wines had considerably lower levels of flavonols and their glycosides, in most cases, being below the detection limit of the HPLC method. Conclusions: There appeared to be no correlation between the flavonol profile and wine variety or region in either white or red wines. Contrary to literature reports of rutin in wine, rutin was not found in any of the wines we analysed, and spiking experiments showed rutin rapidly degraded to the aglycone quercetin. Furthermore, changes in elution order for some quercetin glycoside standards were observed depending upon the acid used in the mobile phase. Significance of the Study: This is the first time the flavonol contents of an extensive cross section of Australian wines have been reported. The concentrations are consistent with those reported in wines from other countries. In light of the instability of rutin in wine, critical review should be given to reports discussing its presence.     

Antioxidant activities of five Chinese rice wines and the involvement of phenolic compounds

Chinese rice wine has been claimed to have health-promoting effects, which may be related to the antioxidant activity in vivo. In this study, total antioxidant, reducing, free radical scavenging, and superoxide anion radical scavenging activities were determined in five Chinese rice wines (Guyuelongshan, Hongqu, Shousheng, Foshou, and Nuomi) comparing with synthetic antioxidants, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Ten individual phenolic compounds including caffeic acid, syringic acid, and rutin, (−)-epicatechin, (+)-catechin, gallic acid, vanillic acid, p-coumaric acid, ferulic acid and quercetin, were identified and quantified by HPLC. Results indicated that rice wines exhibited high antioxidant power, and that total antioxidant activity, reducing capacity and free radical scavenging activity were highly correlated with total phenolic content. Nuomi with the highest content of phenolic compounds showed the highest antioxidant activity, while Foshou had the lowest content with lowest activity. Syringic acid and (+)-catechin contributed most to the phenolic compounds and were highly correlated with all antioxidant properties (r² > 0.75). However, vanillic acid, p-coumaric acid and quercetin showed little contribution to the antioxidant function.     

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.     

Evaluating the antioxidant capacity of wines: a laccase-based biosensor approach

Polyphenolic compounds present in wine have a high antioxidant capacity providing a protective effect on human health. There is a worldwide agreement on this assertion. However, there is no agreement on the method of assessing the antioxidant capacity of wines. The purpose of this study was to emphasize the ability of the laccase-based biosensor developed by our group to evaluate the antioxidant capacity of several types of wine in relation to their polyphenolic content. The values of total antioxidant activity of the investigated wine samples were well correlated with the corresponding bioelectrochemical polyphenol-estimated values, the correlation coefficient obtained being r = 0.9795 (p < 0.05). The linear relationship between total antioxidant activity and bioelectrochemical polyphenol index determined by laccase-based biosensor enabled the calculation of the TEAC (Trolox Equivalent Antioxidant Capacity) of a wine from its bioelectrochemical polyphenol index.     

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.     

The study of phenolic compounds as natural antioxidants in wine

Plant phenolics present in fruit and vegetables, and that are particularly rich in red wine, have received considerable attention because of their potential antioxidant activity. Human consumption of antioxidants has many alleged health benefits, including protection against cardiovascular diseases, and, most recently, cancer. Red wines contain a variety of polyphenolic antioxidants. Five samples of commercial red wines from Spain and four phenolic compounds of red wine: gallic acid, trans-resveratrol, quercetin and rutin, have been studied. The total phenolics content and the total antioxidant activity (TAA) of wines was determined. The total phenolic content, determined according to the Folin-Ciocalteu method, varied from 1800 to 2300 mg/L, expressed as gallic acid equivalents (GAE). The antioxidative effects of wine phenolics were determined using a system based on the inhibition by antioxidants of the absorbance of the radical cation. The relationship between antioxidant activity of phenolic comounds, as hydrogen donating free radical scavengers, and their chemical structures was studied. Furthermore, the total antioxidant activity of the wines investigated was well correlated with phenol content. Thus, the results confirm that red wine polyphenols are, in vitro, significant antioxidants.     

Assessment of some Australian red wines for price, phenolic content, antioxidant activity, and vintage in relation to functional food prospects

Twenty-three Cabernet Sauvignon wines from the Mudgee region and thirty-two Shiraz wines from the Hunter Valley region were analyzed for phenolic content and antioxidant activity. Concentrations of (+)-catechin, quercetin, and transresveratrol, total phenolic content, and DPPH antioxidant activity varied considerably, both within and between varieties. Individual phenols, total phenols, and antioxidant activity were correlated with price and vintage. Shiraz wines showed positive and significant correlations for catechin and quercetin concentrations with total phenols, antioxidant activity, and vintage; and for total phenols and antioxidant activity with vintage. Cabernet Sauvignon wines showed positive and significant correlations for quercetin concentration with total phenols and antioxidant activity. There was a negative and significant correlation found between price and antioxidant activity for Cabernet Sauvignon wines. Results are discussed in terms of the potential for wine to be considered a functional food. PRACTICAL APPLICATION: We report on potential health benefits (antioxidant activity) of 55 wines typical of 2 geographically close, but distinct, wine regions of Australia. Our results highlight the variability in functional components as an issue that needs further research and consideration in relation to wine as a functional food. The price of studied wines is not reflective of their health functionality, based on antioxidant activities.     

Flavonoid glycosides and antioxidant capacity of various blackberry,blueberry and red grape genotypes determined by high‐performance liquid chromatography/mass spectrometry

Anthocyanin and flavonol glycosides of various blackberry, blueberry and red wine grape genotypes were identified and measured by a high‐performance liquid chromatographic (HPLC) separation method with photodiode array (PDA) and mass spectrometric (MS) detection. With this method, two distinct elution regions of anthocyanins and flavonols were obtained with near baseline separation of most compounds. Blackberry, blueberry and red wine grape genotypes varied markedly in total anthocyanins and total flavonols as well as oxygen radical absorbance capacity (ORAC). The respective ranges of total anthocyanin (TA) and total flavonol (TF) contents of tested samples were: blackberries, 1143.9–2415.4 and 102.0–160.2 mg kg^?1; blueberries, 1435.2–8227.3 and 172.5–327.5 mg kg^?1; and red wine grapes, 380.9–7904.7 and 21.0–322.2 mg kg^?1. Antioxidant activities and contents of total anthocyanins and total flavonols in blackberries, blueberries and red wine grapes were highly correlated, with linear relationships between ORAC and TA (r_xy = 0.94) and TF (r_xy = 0.90) for grapes, TA (r_xy = 0.95) for blueberries and TA (r_xy = 0.74) for blackberries. Copyright © 2004 Society of Chemical Industry     

Effects of Vinification Techniques Combined with UV‐C Irradiation on Phenolic Contents of Red Wines

Red wines are typically high in phenolic and antioxidant capacity and both of which can be increased by vinification techniques. This study employed 3 vinification techniques to assess the increase in phenolic compounds and antioxidant capacity. Wines were obtained from Bo?azkere grape cultivar by techniques of classical maceration, cold maceration combined with ultraviolet light (UV) irradiation, and thermovinification combined with UV irradiation and changes in phenolic contents were examined. Total phenolic and anthocyanin contents and trolox equivalent antioxidant capacity of wines were measured spectrophotometrically and phenolic contents (+)‐catechin, (–)‐epicatechin, rutin, quercetin, trans‐resveratrol, and cis‐resveratrol were measured by High Pressure Liquid Chromatography with Diode Array Detection (HPLC‐DAD). As a result of the study, the highest phenolic content except for quercetin was measured in the wines obtained by thermovinification combined with UV irradiation. We demonstrated that the highest phenolic compounds with health effect, total phenolic compounds, total anthocyanin, and antioxidant activity were obtained from thermovinification with UV‐C treatment than classical wine making.     

Evaluation of the antiradical and reducing properties of selected Greek white wines: correlation with polyphenolic composition

The total hydroxycinnamate (THC) and total flavanol (TF) contents were determined in 26 selected Greek white wines of ‘Appellation of Origin of High Quality’ using well‐established spectrophotometric methodology. Furthermore, two parameters related to the antioxidant capacity of wines, the antiradical activity (A_AR) and the reducing power (P_R), were also determined using the stable DPPH· radical and a ferric reducing power assay respectively. THC content varied from 64.4 to 197.1 mg l^?1 chlorogenic acid equivalents (CGAE), whereas TF content exhibited larger variation, ranging from 3.3 to 205.3 mg l^?1 catechin equivalents (CTE). A_AR and P_R were found to range from 0.47 to 0.60 mM Trolox equivalents (TRE) and from 0.32 to 2.05 mM quercetin equivalents (QE) respectively. Regression analysis at 95% significance level indicated that reducing effects are likely to be exerted by the flavanol fraction (SF < 0.05), as opposed to antiradical efficiency which is primarily affected by the sum of THC and TF contents (SF < 0.05), suggesting that synergistic phenomena account for the overall antioxidant status of white wines. © 2002 Society of Chemical Industry     

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     

In vitro antioxidant activity of red grape skins

Phenolic antioxidants seem to be partly responsible for the protective effects against cardiovascular diseases attributed to moderate wine consumption. Grape skins greatly contribute to the phenolic composition of red wine. In this paper, the in vitro antioxidant activity of red grape (Vitis vinifera) skins is determined. We show that the radical scavenging activity (C ₅₀ values) against 2,2-diphenyl-1-picrylhydrazyl (DPPH^·) of grape skin extracts is relatively high (3.2–11.1 mg dried skin/mg DPPH^·) in relation to other foodstuffs and, as expected, is influenced by grape variety, stage of grape ripening and vintage. The antioxidant potential of grape skins seems to be transferred into wine since grape varieties with skins exhibiting high antioxidant potential also resulted in wines with high antioxidant activity. Statistically significant correlations were found between antioxidant activity and phenolic content (total polyphenols, proanthocyanins, catechins and anthocyanins) for both grape skins and wines.     

Measurement of total phenolic content in wine using an automatic Folin–Ciocalteu assay method

Measuring the total phenolic content in wine is important in estimating the taste and health benefits of wine. We developed an automatic Folin–Ciocalteu (F‐C) method to reduce processing times (3 min), human errors and waste volume as compared it to the manual method. The gallic acid standard responded linearly up to 5000 μg mL^?1, and the wine dilution series responded linearly between four‐ and sixteenfold dilutions. Anthocyanins showed slower reaction rate compared with wine, gallic acid and quercetin, while ascorbic acid showed the fastest rate. Fructose and glucose at the 10% level showed approximately 8% interference in port wines, and the interference was thought to be negligible in most dry wines containing <1% sugar. Total phenolic contents ranged between 1600 and 3300 μg mL^?1 by the automatic method and were approximately 20% less than those by the manual method, except in pink wines which was nearly identical. The regression analysis of the phenolic contents showed a very linear relationship between the methods (r² = 0.97***). This automatic method was thought to be efficiently adopted in wine testing laboratories as a fast and reproducible assay.     

Antioxidant and antimicrobial properties of polyphenolic fractions from selected Moroccan red wines

The present study is the first effort to a comprehensive evaluation of the antioxidant and antimicrobial activities of fractionated red wines from Morocco. The results obtained revealed that the wine samples were characterized by a higher phytochemical concentration than the same variety of wines with a different geographical origin and other more consumed red wines, confirming what was reported in a previous authors' work. The most phenolic-rich fractions were the ones containing phenolic acids and quercetin glucoronides from Syrah and Merlot wine samples while Cabernet Sauvignon exhibited the highest monomeric anthocyanin content. The antioxidant activity of wine extracts was tested by ferric reducing antioxidant power and 1,1-diphenyl-2-picrilhydrazyl assays. Samples revealed a higher reducing capacity than radical scavenging property and a good correlation between antioxidant activity and polyphenolic content values. As regards the antimicrobial properties, each fraction exhibited activity against a broad spectrum of food-borne microorganisms, revealing not only a moderate to high natural preserving capacity, but also potentially beneficial influence on human health. PRACTICAL APPLICATION: In consideration of the scarcity of data regarding composition and biological properties of Moroccan red wines, the present study may represent a valuable reference for wine consumers and producers.     

Phenolic compounds and antioxidative properties of selected wines from the northeast of Thailand

The phenolic contents and antioxidative properties of selected wines, produced in the northeast of Thailand, were evaluated and compared, particularly those produced at Suranaree University of Technology (SUT) Farm as a case study. Nine wine varieties were used to evaluate their total phenolic content (TPC) by Folin–Ciocalteu method, free radical scavenging efficacy by DPPH method and reducing power by ferric reducing-antioxidant power (FRAP) method. The red wines had significantly higher (p < 0.05) amounts of total phenols, flavonoids and antioxidant activities (AA) compared to white wines. Capillary electrophoresis (CE) was used as a powerful and high performing tool for analysis of principal phenolic compounds in the wines. t-Resveratrol was found in Shiraz, Zinfandel and blended wine varieties. (+)-Catechin was found in all wine varieties, except in Chasselar Dore. (+)-Catechin was present in wines at a higher level than (−)-epicatechin. In red wine, gallic acid was the dominant phenolic acid found.     

Phenolic profile and free radical‐scavenging activity of Cabernet Sauvignon wines of different geographical origins from the Balkan region

BACKGROUND: The phenolic profile, determined by the relative proportions of different phenolic compounds, is characteristic for each grape variety and its corresponding wine. The aim of this study was to determine the phenolic and hydroxycinnamate acid, flavan‐3‐ol and flavonol contents and free radical‐scavenging activity of single‐cultivar (Cabernet Sauvignon) wines from selected Balkan vineyard regions by spectrophotometric methods and high‐performance liquid chromatography with photodiode array and fluorescence detection. RESULTS: The contents of phenolic compounds varied depending on the agroclimatic factors and oenological practices of the vineyard region. The antioxidant activity of wine samples was estimated by their ability to scavenge the stable 2,2′‐diphenyl‐1‐picrylhydrazyl free radical (DPPH). All wines showed high DPPH‐scavenging activity (70.03–83.53%, mean 73.76%). Significant correlations between catechin (R² = 0.8504) and quercetin (R² = 0.8488) concentrations and DPPH‐scavenging ability of the wines were found. CONCLUSION: The concentrations of the main components catechin and quercetin can be used as biochemical markers for the authentication of red grape cultivars and their corresponding single‐cultivar wines. Copyright © 2010 Society of Chemical Industry     

Phenol content,antioxidant activity and metal composition of Croatian wines deriving from organically and conventionally grown grapes

The present study was performed to evaluate the antioxidant capacity, the polyphenol and metal content of conventionally and organically produced wines, which underwent similar winemaking processes. The wine grapes were grown under well-defined organic and conventional conditions from the two different wine-growing sub-regions of Croatia, Prigorje and Southern Dalmatia. The values of antioxidant activity, as evaluated by two free radical methods, ABTS and DPPH, was found systematically higher in organic wines compared to conventional ones. In a reversed phase HPLC analysis, used in order to characterise the phenol fraction of wines, higher concentrations of chlorogenic acid, ferulic acid, catechin, trans-resveratrol, all studied hydroxybenzoic acids and flavonols were found in the organically produced wines. No apparent trend was found in the metal contents of the wines, but ICP-MS analysis confirmed that both wine productions, organic and conventional, were well within the toxicological safety limits.     

Effect of grape processing on selected antioxidant phenolics in red wine

Wine, particularly red wine, is an important source of polyphenols and several studies have shown that moderate wine consumption is associated with a reduced risk of coronary heart disease. It has been hypothesized that these antioxidant compounds may be responsible for the potential beneficial effects of wine. The influence of different vinification techniques (fermentation on skin [A], mash heating [B], and the combination of both [C]) on the antioxidant capacity and the phenolic composition of red wines (Spätburgunder [Pinot Noir], Lemberger, and Cabernet Franc) were tested in the present study. The highest concentrations of anthocyanins, flavan-3-ols, flavonols, stilbenes, and antioxidant capacity were found in the red wines which were produced under the conditions of C, followed by B and A.     

A comparative study on the antioxidant properties of Slovakian and Austrian wines

The antioxidant properties of 86 wine samples (35 white and 17 red from the Slovak, and 12 white and 22 red from the Burgenland, regions) were investigated by Electron Paramagnetic Resonance (EPR) spectroscopy using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt cation radical (ABTS⁺) as oxidants. Generally, the red wines showed, on the average, more than 10 times higher antioxidant activity towards ABTS⁺ than the white wines. A similar ratio was found for the total phenolics content. A linear correlation was found between the antioxidant activities determined by DPPH and ABTS⁺ and the phenolics concentration. This trend is supported by the significant difference of the total integral value of the aromatic region in ¹H NMR (Nuclear Magnetic Resonance) spectra between the red and white wine samples. The content of the phenolic acid components of 16 selected wine samples determined by High Performance Liquid Chromatography (HPLC) correlates with the antioxidant activities. No significant differences were found between Slovakian and Austrian wines.