Browning of white wines: correlation with antioxidant characteristics, total polyphenolic composition and flavanol content

Browning is a serious problem in relation to white wine quality, which mostly affects the sensory attributes. It is well known to be associated with polyphenol oxidation, and therefore it may be accompanied by changes in the antioxidant capacity. On the basis of this consideration, thirteen experimental white wines, vinified and stored under identical conditions, were subjected to accelerated browning, and efforts were made to distinguish compositional parameters that might be related to the extent of browning development. Further, the relation of browning with the reducing power and the antiradical activity were assessed. Regression analysis at 95% significance level indicated that the antiradical activity is likely to be exerted principally by the flavanol fraction (r² = 0.92) and to a lesser extent by total phenols (r² = 0.85), as opposed to reducing power, which is mainly affected by total phenols (r² = 0.78), suggesting that synergistic phenomena account for the overall antioxidant status of white wines. In addition, the total phenolic and flavanol concentration correlated significantly with the browning rate constants and provided strong evidence that browning development might be predominately associated with flavanol (r² = 0.84) and to a lesser extent with total phenolic (r² = 0.79) oxidation.     

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.     

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     

Sensory assessment and chemical measurement of astringency of Greek wines: Correlations with analytical polyphenolic composition

The purpose of this study was to measure the astringency of selected Greek red wines and to assess the relationship between sensory and chemical data. Nine red wines produced by three native Greek grape varieties (agiorgitiko, xinomavro and mavrodafni) were used and their astringency and bitterness was assessed by a trained panel. In addition, their astringency was estimated chemically employing the ovalbumin precipitation method. Their polyphenolic composition was also determined by High Performance Liquid Chromatography (HPLC). The sensory data showed that mandilaria was the most astringent variety whereas agiorgitiko was the least. Statistical analysis of the results indicated that the chemical data obtained for astringency significantly correlated with the sensory determinations. In addition, significant correlations were obtained between the sensory data and the wine polyphenolic composition.     

不同产区葡萄酒多酚物质抗氧化活性差异及相关性分析

以西北部产区(焉耆盆地、吐哈盆地、天山北麓、伊犁河谷)及中部产区(河北产区)葡萄酒为样本,测定其多酚组成及抗氧化能力,分析样品间差异性及相关性,探究影响抗氧化功效的单体酚物质.通过对酚类物质含量、DPPH、ABTS+、羟自由基清除率的测定,结果显示,西北部产区样品酚类物质含量高,且种类丰度较高;焉耆与伊犁产区葡萄酒抗氧...     

Hydroxycinnamates of Vitis vinifera: Sensory assessment in relation to bitterness in white wines

The bitter and astringent taste properties of hydroxycinnamoyl tartaric acids have been responsible for incorrect speculation that these compounds influence the taste of wine. The sensory contribution of the major hydroxycinnamates found in wine was evaluated by duo—trio difference tests in model wine solutions and in white wine. The major hydroxycinnamate compound, trans-caffeoyl tartaric acid, was not detectable when added at the highest level at which it has been found in wine, 150 mg litre^?1. Similarly, no significant difference in taste was produced when caffeic acid and p-coumaric acid were added at 120 mg litre^?1 and 30 mg litre^?1, respectively. Trans-2-S-glutathionyl caffeoyl tartaric acid, a product of oxidase activity in must, was not detectable at 50 mg litre^?1. It was concluded that the hydroxycinnamates do not play any direct role in the taste of wines.     

Spectral evaluation of total phenolic components in Vitis vinifera: Grapes and wines

Whereas high levels of flavonoid extractives are responsible for the characteristic λ_Dmax at about 280 nm in the ultra-violet spectra of red wines, there is wide variability in the spectral features of natural white wines, in which the phenolic content is often minimal. For the latter, λ_Dmax may occur anywhere within the range 265–285nm, with relatively strong absorbance at 320 nm arising from the presence of hydroxycinnamate esters. Massive fining of many white wines and juices with polyvinylpyrrolidone (10% w/v) has shown residual non-phenolic u.v. absorbing constituents to be sufficiently uniform to enable direct spectral measurement of total hydroxycinnamates in white juices, white wines and rosés as (E₃₂₀-1.4) absorbance units. For white grape juices and white wines, total hydroxycinnamates are directly quantitated as mg litre^?1 ‘caffeic acid equivalents’ and total flavonoid extractives may also be estimated. Total phenolic components of red wines are accounted as (E₂₈₀-4) absorbance units. The spectral interpretations enable comparative estimation of flavonoid extractives in all natural wine types.     

Browning development in white wines: dependence on compositional parameters and impact on antioxidant characteristics

Browning is a serious problem in relation to white wine quality and mostly affects the sensory attributes, whereas its impact on the dietary value of wines has never been investigated. Browning, however, is well known to be associated with polyphenol oxidation, and therefore it may be accompanied by changes in the antioxidant capacity. On the basis of this consideration, experimental white wines vinified and stored under identical conditions were subjected to accelerated browning, and efforts were made to distinguish compositional parameters that might be related to the extent of browning development. Further, the consequences of browning on the reducing power and antiradical activity were assessed. It was shown that none of the parameters examined (titratable acidity, pH, total SO₂, total polyphenols and total flavanols) play an important role in browning onset, but SO₂ appeared to exert a statistically significant influence (r²=0.6394, P<0.05) on the percentage change in the antiradical activity. Evidence also suggested that browning development might be prominently associated with decreases in both antiradical activity (r²=0.7891, P<0.01) and reducing power (r²=0.6925, P<0.05).     

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.     

Influence of yeast mannoproteins in the aroma improvement of white wines

Abstract: In the present work, 3 different yeast strains (1, 2, and 3) were used to elaborate white wines using Albariño must. The concentration of polymeric mannose was determined using a method based on the mannoprotein precipitation, hydrolysis and analysis of sylylated mannose derivatives by gas chromatography. Wines elaborated with the strain 1 (W1) presented a higher mannoprotein concentration than the other wines. The analysis of the volatile composition of wines showed significant differences (P < 0.05) among them, being W1 which presented the highest concentration of aroma compounds, mainly terpens and norisoprenoids. The sensorial analysis of wines also showed that W1 had the best quality. The results obtained from this work demonstrate that mannoproteins could be involved in the behavior observed. Some evidences were obtained using a model wine, where 2 major terpens in W1 were preferentially retained by the colloids rich in mannoproteins released by strain 1. Practical Application: White wines elaborated with yeast strains overproducing mannoproteins could have better quality than others. Mannoproteins could contribute to aroma enhancement of Albariño white wines     

Original article: Prediction of the colour and polyphenolic composition of the young red wines from the phenolic potential of the grapes

The phenolic potential of the grapes of Tannat, Cabernet Sauvignon and Merlot produced in the south region of Uruguay was analysed in four years. The grapes of Tannat had the highest total phenolic richness (A280 = 80.0), total anthocyanin potential (ApH1 = 2540 mg L^?1) and extractable anthocyanin potential (ApH3.2 = 1269 mg L^?1), although there were important differences between the years. Representative winemaking of each vineyard was carried out. The differences verified in the grapes phenolic indexes were related to the colour and polyphenolic composition of the wines. The correlations between the phenolic indexes of the grapes and the colour and polyphenolic composition of the wines were very high. The estimation of the polyphenolic richness and the extractability of the anthocyanins of the grapes allow to improve the management of the winemaking and the prediction of the chromatic characteristics and the global polyphenolic composition of the wines.     

Screening of the antioxidant properties and polyphenol composition of aromatised green tea infusions

BACKGROUND: Aromatised green teas are widely sold and popular owing to their fragrance. In this study the antioxidant activity of six commercial green tea infusions was assessed by three complementary assays. RESULTS: In order to evaluate the tea infusions as antioxidant sources, their phenolic content (Folin‐Ciocalteu assay), cupric ion‐reducing antioxidant capacity (CUPRAC) and 2,2‐diphenyl‐1‐picryhydrazyl (DPPH) radical‐scavenging ability were determined. Their content of polyphenols was also determined by high‐performance liquid chromatography/mass spectrometry (HPLC/MS) in negative electrospray ionisation mode. Some teas with citrus aroma, besides having a relatively high content of catechins, also contain other phenolic compounds such as naringin and hesperidin. The three assays used to evaluate the antioxidant capacity of the tea infusions gave different rank orders. Therefore an antioxidant index was calculated for better correlation of the results, and its highest value was obtained for Clear Green Mint tea infusion. CONCLUSION: The studied teas, besides having a relatively high content of catechins, also contain naringin and hesperidin, which are not present in ‘pure’ green tea. It is important to run multiple assays to get a better estimate of the antioxidant capacity of a given sample. Copyright © 2012 Society of Chemical Industry     

红心与白心火龙果总糖、还原糖含量及其抗氧化活性的对比分析

以红心与白心火龙果为原料,采用热水浸提法提取果肉中的糖分。分析比较2种火龙果总糖、还原糖含量及其抗氧化活性。试验表明,温度对糖分提取具有显著影响。在80℃时,红心火龙果总糖(28.68%)及还原糖(8.85%)含量均显著高于白心火龙果总糖(18.46%)及还原糖(7.09%)含量。抗氧化活性测试结果显示,其抗氧化活性随多糖浓度的升高而增强,其中红心火龙果多糖的抗氧化活性强于白心火龙果。当多糖浓度为2.0 mg/mL时,红心火龙果多糖对·OH、DPPH、NO2-的清除率可达73.44%、48.39%、47.59%,总抗氧化力为0.79,总还原力为0.65。     

Impact of phytosanitary treatments with fungicides (cyazofamid, famoxadone, mandipropamid and valifenalate) on aroma compounds of Godello white wines

Cyazofamid, famoxadone, mandipropamid and valifenalate, four new fungicides for controlling downy mildew in vine, were applied to an experimental vineyard producing Vitis vinifera white grapes of the Godello variety. Following harvest, the grapes were subjected to single vinification runs. The odour activity values (OAVs) for the Godello white wines obtained were estimated with a view to assessing potential alterations of their aroma composition by effect of the phytosanitary treatments. Several fatty acids, their esters and acetates were formed during the winemaking process in high levels and could be expected to strongly influence the aroma of the wines by introducing floral, fruity and spicy nuances. The concentrations of six compounds (2-phenylethyl acetate, ethyl butanoate, ethyl octanoate, 4-vinylguaiacol, 3-methylbutanoic acid and methionol) were found to suffice with a view to discriminating between wines from grapes treated with fungicides under Critical Agricultural Practices (CAP) and under Good Agricultural Practices (GAP).     

Modification of the polyphenolic and aromatic fractions of red wines aged on lees assisted with ultrasound

The ageing on lees is a technique particularly interesting in the production of red wines due to the possibility of enhancing some of their sensory characteristics. Different authors have researched the ultrasound assistance to accelerate this ageing process in wines. The present work evaluated the modification that both fractions, polyphenolic and aromatic, of red wines suffer during the ageing on lees process assisted with ultrasounds and with the addition of oak chips. The results obtained during the experimental design indicate that the ultrasound treatment decreased the concentration of proanthocyanidins (between 20.3% and 32.8% with and without oak chips, respectively) and the total pigment content (with the highest reduction in the control sonicated wine 55.9% without chips and lees and from 47.8% to 48.9% when having oak chips/lees and lees, respectively). In addition, it has been observed that the ultrasound treatment did not affect the amount of fermentative volatile compounds present in the wine but, it increased the concentration of phenolic aldehydes coming from oak wood chips (10.8% in control wine and from 35.92% with oak chips/lees to 55.8% with lees).     

Combined heat and proteolytic enzyme treatment of white wines reduces haze forming protein content without detrimental effect

Laboratory heat treatments of wines at both medium and high temperatures, with and without the addition of proteolytic enzymes have resulted in reduced protein content and bentonite requirements for heat stability. Increasing sulfur dioxide concentration of the wines resulted in additional reductions in protein content after treatment. Pilot scale experiments (50L batches) were done using two proteolytic enzyme preparations and three commercial wines that had not been bentonite fined. Wines with and without enzyme addition were heated at 90°C for 1 minute in a tubular heat exchanger, then immediately cooled to 16°C to 19°C. This combined heat and enzyme treatment reduced the protein levels in all wines to between 40% and 80% of the original levels. Heat treatment alone reduced the protein levels to between 50% and 90%. The bentonite-fining requirement was reduced to between 30% and 60% in the combined heat and enzyme treated wines, compared to the heat alone treatment that reduced the requirement to between 50% and 70%, of the bentonite requirement for the untreated wines. Sensory evaluation of the wines showed that the treatments had negligible effect on aroma and no effect on palate characteristics. There were some slight effects on aroma in some cases from heating and from enzyme addition but the dosage was much higher than that recommended by the enzyme manufacturer. Separate experiments in which wine was heated at 45°C for 1 day gave results similar to those obtained with short term heating at 90°C in respect of reduced bentonite fining requirements.     

Influence of some prefermentative treatments on aroma composition and sensory evaluation of white Godello wines

The influence of the static settling time and the addition of ammonium salts on basic parameters, aroma composition and tasting of white Godello wines have been studied. The statistical analysis showed a significant influence of those treatments on several analytical parameters. The static settling time proved to be very influential on total acidity, free sulphur dioxide, esters, terpenols and fatty acids, while the addition of ammonium salts showed a significant effect on higher alcohols and ethyl lactate. According to the odour active value (OAV), 14 out of 47 studied volatile components had OAV >1 in all the analysed wines, while six volatile components showed OAV >1 only for some of them. Ethyl octanoate, isoamyl acetate and ethyl hexanoate showed the highest OAV values. During the tasting session, the two studied factors became relevant, being better valued the wine made with must containing higher limpidity and with the addition of diammonium hydrogen phosphate.     

Replacement of sulfur dioxide by lysozyme and oenological tannins during fermentation: influence on volatile composition of white wines

BACKGROUND: In recent years the use of sulfur dioxide, a commonly used additive in winemaking, has been questioned because of its toxic effects on human health. Studies have been conducted to find alternatives that can effectively substitute for this additive in all its various technological functions. In previous work, lysozyme and oenological tannins were found as possible substitutes in controlling bacterial undesirable fermentations and phenolic oxidation. However, data on the volatile composition of wines obtained by that protocol are lacking. In this work, the effects on volatile composition of white wines by the substitution of SO₂ during fermentation with lysozyme and tannin were studied. At the same time, the technological performance of two strains of yeast that produce low amounts of SO₂ were evaluated. RESULTS: The results showed that both SO₂ and lysozyme prevented the development of undesirable bacterial fermentations. The study of volatile compounds shows differences in the alcohol, acid and ester contents among the final products: wines fermented with strain 1042 and lysozyme had higher total alcohol concentration, while the addition of SO₂ promoted higher production of 3‐methyl‐1‐butanol, 3‐methylthio‐1‐propanol, phenylethyl alcohol and 4‐hydroxy‐benzenethanol. Esters, as a total, were influenced by the different strain and tannins addition, while amounts of medium‐chain fatty acid ethyl esters and their corresponding fatty acids were found in higher amounts in wines coming from fermentations with lysozyme. The sensory analysis revealed a preference for wines to which lysozyme and tannins had been added. CONCLUSION: The data suggest that the addition of lysozyme and oenological tannins during alcoholic fermentation could represent a promising alternative to the use of SO₂ and for the production of wines with reduced content of SO₂. The composition of the volatiles in the final wines was affected by the different vinification protocols (mainly with regards to alcohols and ethyl esters). Copyright © 2009 Society of Chemical Industry     

Evaluation of the effect of processing on cocoa polyphenols: antiradical activity,anthocyanins and procyanidins profiling from raw beans to chocolate

The content and composition of anthocyanins and procyanidins in fermented cocoa beans (from different geographic origins: Ecuador, Cameroon, Ivory Coast, Ghana and Nigeria), roasted nibs, cocoa mass and chocolate were determined, beside the determination of the total antiradical capacity. Concerning geographic origin, cocoa beans and processed products from Ecuador showed the highest levels of anthocyanins, followed by Nigeria and Cameroon. Generally, as cocoa beans were further processed, the levels of anthocyanins and flavan‐3‐ols decreased. The largest observed losses of phenolics occurred during roasting. A progressive decreasing trend in polyphenol concentration was observed in the other processed samples as well. Despite the original content of polyphenols in raw cocoa beans, technological processes imply a significant impact on cocoa quality, confirming the need of specific optimisation to obtain high value chocolate.