Examination of the sulfur dioxide–ascorbic acid anti‐oxidant system in a model white wine matrix

The effectiveness of sulfur dioxide in inhibiting the ascorbic acid induced oxidation of (+)‐catechin in a matrix simulating white wine was investigated. At a sulfur dioxide:ascorbic acid mole ratio of 0.8:1.0, sulfur dioxide extended the delay prior to the onset of (+)‐catechin browning as measured by the increase in absorbance at 440 nm from 2 to 4 days post reaction initiation. The lengthening of the pre‐browning period was correlated with an increase in the time required to oxidise ascorbic acid completely, the sequence of events being loss of sulfur dioxide (day 3), loss of ascorbic acid (day 4) and on‐set of (+)‐catechin browning (day 4). Increasing the sulfur dioxide to ascorbic acid mole ratio to 3.0:1.0 inhibited the onset of (+)‐catechin browning over the 14‐day reaction period. This inhibition was achieved at considerable cost to the sulfur dioxide concentration, with the ratio of sulfur dioxide consumed to ascorbic acid oxidised being 1.7 compared with the expected fraction of 1.0. Reasons for the enhanced consumption of sulfur dioxide and the implications of this study for maintenance of quality in white wine production are discussed. Copyright © 2004 Society of Chemical Industry     

An Alternative Method for the Determination of Some of the Antioxidant Phenolics in Varietal Turkish Red Wines

The concentration of eight biologically important phenolic compounds (β‐coumaric acid, gallic acid, ferulic acid, caffeic acid, trans‐resveratrol, quercetin, (+)‐ catechin and (?)‐ epicatechin) of red wines produced on a pilot plant scale were determined using gas chromatography with mass spectrometric detection in the selective ion monitoring mode (GC/MS‐SIM). The procedure involved an easy fractionation and liquid‐liquid extraction method. For derivatization, BSA [N,O‐bis‐trimethylsilyl aceta‐mide] / TMCS was used. The results showed that the p‐coumaric acid, gallic acid, ferulic acid, caffeic acid, trans‐resveratrol, quercetin, (+)‐ catechin and (?)‐epicatechin levels in the wine samples ranged between 2.05 and 4.21 mg/L; 21.78 and 60.83 mg/L; 0.33 and 0.82 mg/L; 1.50 and 4.06 mg/L; 0.96 and 3.93 mg/L; 2.66 and 3.14 mg/L; 8.72 and 11.30 mg/L; 5.50 and 9.58 mg/L, respectively. Although the quercetin and trans‐resveratrol levels of Turkish red wines were similar to previously reported values, (+)‐ catechin and (?)‐ epicatechin levels were lower than the values of red wines originating from other countries.     

The influence of ascorbic acid on the composition, colour and flavour properties of a Riesling and a wooded Chardonnay wine during five years' storage

This paper presents the results from an investigation to assess the development of a Riesling and a wooded Chardonnay wine over five years. The wines were bottled either with or without added ascorbic acid and stored under controlled temperature and humidity conditions. Ascorbic acid addition to wine at bottling had little effect on wine aroma and flavour when the wines in this study had been in bottle for 6 months or less. For both wines, at bottle storage times of 3 years or more, addition of ascorbic acid at bottling resulted in wines with no difference in aroma or less oxidised and/or more fresh fruity aromas, even if all the ascorbic acid had been depleted at the time of assessment, compared to wines without addition of ascorbic acid at bottling. In terms of colour, for the Chardonnay wines, the effect of ascorbic acid addition at bottling assessed between two weeks and two years after bottling suggested that wines without addition were browner and had more overall colour intensity. For the Riesling wines, ascorbic acid addition had no significant effect on brownness and overall colour intensity although the Riesling wines with ascorbic acid were generally higher in yellow colour. The A₄₂₀ measurements, which are widely used to estimate the brown colour of wines, did not always appear to correlate with the brown scores obtained by visual assessment or colour measures by CIELAB when wines with and without ascorbic acid addition were compared together. For both wines, after three and five years storage, the concentration of the antioxidant sulfur dioxide was either little different or else slightly(statistically significantly) higher in wines to which ascorbic acid was added at bottling than those without addition.     

The effect of ascorbic acid on oxidative browning of white wines and model wines

The effects of ascorbic acid addition to white wines and model wines were either anti-oxidative or pro-oxidative, and depended, inter alia , on the duration of storage. Soon after its addition, ascorbic acid decreased the redox potential and brown colour of model wines and white wines. However, with time, these effects were reversed, and redox potential, SO₂ consumption and browning were greater in samples with added ascorbic acid. The point at which the net effect of ascorbic acid addition was to increase browning occurred earlier at higher SO₂ levels. Under a variety of accelerated (45®), or prolonged (ranging from three months to five years) storage conditions, the browning of model wines and white wines was invariably enhanced by ascorbic acid addition, and this enhancement took place whether or not SO₂ was present. The addition of SO₂ alone, rather than ascorbic acid alone or SO₂ plus ascorbic acid, appears to be the most effective and least expensive way of protecting white wine from browning during bottle conservation.     

红糖醋不同发酵阶段产物有机酸变化及抗氧化活性研究

以红糖为原料,采用液态深层发酵法酿造红糖醋,分析红糖醋不同发酵阶段产物有机酸组成,研究总多酚、总黄酮含量及抗 氧化活性的变化。 结果表明,红糖醋、红糖酒醪及红糖液分别检出10种、9种及8种有机酸,主要为乙酸、乳酸、甲酸、抗坏血酸、琥珀酸、 苹果酸、柠檬酸、草酸。 红糖液中琥珀酸和红糖醋中乙酸含量最高,分别为4 971.09 mg/L和28 273.35 mg/L。 在发酵过程中,红糖液中 总多酚和总黄酮含量由0.94 mg/mL和0.50 mg/mL降至红糖醋中0.87 mg/mL和0.17 mg/mL。 不同发酵阶段产物抗氧化能力的顺序为红 糖液＞红糖酒醪＞红糖醋。 总多酚和总黄酮含量与DPPH自由基清除能力有一定相关性,相关系数分别为0.855 5和0.883 0,与总还原力 有较强的相关性,相关系数分别为0.9078和0.9093。     

不同抗氧化剂对白葡萄酒品质的影响

将甘露聚糖、谷胱甘肽加入瓶装葡萄酒中，检测不同处理后白葡萄酒在储存期间颜色、酚类化合物和香气的变化，并通过感官品评来评估抗氧化剂对葡萄酒品质的影响。结果表明，添加20 mg/L甘露聚糖能有效抑制白葡萄酒颜色褐变，降低白葡萄酒的黄、绿色调及色差，提升酒体明亮度；显著延缓儿茶素和表儿茶素的氧化速率（高于对照组61.9%、39.7%），提高没食子酸的浓度（56.91%），但总酚含量总体呈递减趋势，表明抗氧化剂选择性保护了部分酚类物质；有效降低辛酸乙酯，乙酸异戊酯等酯类物质的水解（高于对照组2.97～5.77倍），保护了葡萄酒的花香味；并减少辛酸、己酸和正葵酸等酸性化合物的含量（低于对照组59%、70.07%和91.24%），降低了葡萄酒的奶酪腐败味；添加20 mg/L甘露聚糖白葡萄酒感官评分最高，为81分。     

Effect of bottle colour and storage conditions on browning of orange wine

We investigated the effect of bottle colour, storage temperature and storage time on the browning of orange wine. Kozan orange variety was used for the production of wine. The fermentation was performed spontaneously at 20 degrees C. The wine was bottled in three differently coloured bottles: clear white, green and brown. Then each was divided into two parts: one part was stored at 13-14 degrees C in the cellar and the other at 23-26 degrees C in the laboratory for 150 days. During the storage, browning index and ascorbic acid content of the wines were measured at day 0, 75 and 150. The results showed that the use of brown bottles and the short-time storage reduced the browning in orange wines, however, storage at two different temperatures did not significantly affect the browning index.     

Factors influencing the production and stability of xanthylium cation pigments in a model white wine system

The influence of various wine parameters on the production and stability of xanthylium cation pigments in a wine-like medium is reported. The xanthylium pigments have an absorbance maximum in the visible region at 440 nm that is close to the measured absorbance used by the wine industry to indicate the browning of wine (i.e. 420 nm). The results of this study show that iron is more efficient than copper in both the colouration and production of xanthylium cation pigments in wine-like solutions of tartaric acid and (+)-catechin. The non-flavonoid caffeic acid can inhibit the accumulation of the xanthylium cation pigments, despite the presence of metal ions, and also influence the stability of the pigment. Sunlight leads to a decrease in the concentration of xanthylium cation pigments while a temperature difference of 20 ^oC in the absence of light was observed to have little influence on concentration. The results suggest that the xanthylium cations are more likely to be a transitory species during white wine oxidation rather than accumulating pigments based on their instability with caffeic acid.     

Color Degradation in an Ascorbic Acid-Anthocyanin-Flavanol Model System

Interactions between ascorbic acid, pelargonidin-3-glucoside, and catechin were studied in pH 3.4 citrate-phosphate buffer at 20°C under anaerobic and oxygenated conditions. Changes in anthocyanin pigment, ascorbic acid, dehydroascorbic acid, and catechin were quantitatively measured during 130 days storage along with Hunter color parameters, browning, and polymeric color. Ascorbic acid had a statistically significant effect on all parameters, including anthocyanin loss under both oxygen and nitrogen environments, catechin loss, increase in browning and polymeric color, decrease in Hunter “a” value and increase in Hunter L value. Ascorbic acid bleached anthocyanin pigment and also induced browning. There is evidence that anthocyanin pigment and ascorbic acid degrade through a direct condensation mechanism.     

5种浆果果酒抗氧化活性差异及综合评价

该研究测定了5种浆果（蓝莓（野生和北陆）、蓝靛果（野生和蓓蕾）、不老莓）果酒的理化指标、单体酚类物质含量和抗氧化活性,探究5种浆果果酒抗氧化活性差异,并通过主成分分析（PCA）对其进行综合评价。结果表明,野生蓝靛果果酒中的总糖、总酸、多酚、黄酮、花色苷含量最高,分别为3.82%、9.69 mg/g、12.58 mg/g、1.55%、1.21 mg/g,单体酚类物质中咖啡酸、儿茶素、表儿茶素、绿原酸、对香豆酸、芦丁含量最高,分别为66.19 mg/g、878.09 mg/g、13.28 mg/g、735.50 mg/g、275.32 mg/g、23.86 mg/g,其DPPH·清除率（92.29%）、 ·OH清除率（96.28%）和还原力（1.744）最强;野生蓝莓果酒的ABTS+·清除率（96.77%）和O2-·的清除率（50.54%）最强;浆果果酒综合得分表明,5种浆果果酒的抗氧化活性排序为野生蓝莓果酒＞野生蓝靛果果酒＞蓓蕾蓝靛果果酒＞不老莓果酒＞北陆蓝莓果酒。     

Enhancement of red wine colour by pre-fermentation addition of copigments

The effects of pre-fermentation additions of catechin and caffeic acid to musts were investigated. The cultivar Listan negro, a major red grape grown in the Canary Islands, was used for these studies. The addition of catechin at 120 mg/l resulted in only 10% enhancement in wine colour (AU at 520 nm) after fermentation, while caffeic acid, at the same level, enhanced the wine colour by 60%. These results appear to be the first report of such a significant increase in wine colour achieved by pre-fermentation treatments with natural grape constituents, supporting the view that red wine colour is generally limited by the levels of cofactors for copigmentation rather than by the level of anthocyanins alone. This demonstrates the importance of non-pigment composition in establishing red wine colour and the influence of initial must composition.     

反相高效液相色谱法测定猕猴桃酒中的多酚物质

建立了猕猴桃酒中多酚的RP-HPLC检测方法该方法的最低检测限小于1．0mg／L,加标回收率均大于90％。RSD％小于6％,说明该方法准确可靠。用该方法对自制猕猴桃酒中多酚物质进行检测,得出样品中主要有：原儿茶酸、儿茶素、香草酸、咖啡酸、表儿茶素、香豆酸、槲皮素等13种多酚物质。     

Citric acid and the browning of solutions containing ascorbic acid

Model systems were used to simulate lemon juice so that the findings may be applicable to the non-enzymic browning phenomenon which occurs on storage of citrus juices. The addition of citric acid to systems containing ascorbic acid resulted in augmented chromophore development. Evidence is given to show that citric acid neither acts as a catalyst nor yields reactive carbonyl compounds under aerobic incubation conditions. Thin-layer chromatographic separation of the brown pigments in different systems demonstrated a specific chromophore which occurred only when citric acid and ascorbic acid were both present. The presence of amino acids in ascorbic systems is the major contributor to the development of browning but it is suggested that citric acid, or a derivative, is incorporated into some of the brown pigments.     

Antioxidant phenolic compounds of pomegranate wines produced by different maceration methods

Various methods were evaluated in the production of ‘Hicaz’ pomegranate wine by microvinification. The chemical, phenolic and antioxidant characteristics of the wines were assessed by measurement of water‐soluble dry matter, acidity, density, alcohol content, volatile acidity, total monomeric anthocyanins, polarized colour intensity and individual phenolic compounds. Three different methods – classical maceration (N), seed‐supplemented maceration (S) and seed + enzyme supplemented maceration (E) – were applied. Total phenolic compounds of pomegranate must and wines (after 18 months of storage) were 1897 mg/L (must), 1663 mg/L (N), 1339 mg/L (E) and 1414 mg/L (S). Phenolic compounds in pomegranate must and wines included gallic acid, vanillic acid, caffeic acid, ferulic acid, p‐coumaric acid, hydroxycinnamic acid, epicatechin and catechin. Total antioxidant capacities (Trolox equivalents) of pomegranate must and wines (N, E and S) were 9.9 mm /L (must), 9.8 mm /L (N), 9.7 mm /L (E) and 9.5 mm /L (S). Copyright © 2017 The Institute of Brewing & Distilling     

Influence of aerobic and anaerobic conditions and yeasts on the reaction between (+)-catechin and glyoxylic acid

The reaction between (+)-catechin and glyoxylic acid in wine model solutions was studied under aerobic and anaerobic conditions in the presence and absence of yeasts with a view to determine their contributions to browning of white wine. Under aerobic conditions, the presence of yeasts reduced the production of colored products, the formation rate of which was similar to that observed under anaerobic conditions and in the absence of yeasts. These results reveal that yeasts and intermediate reaction products compete for oxygen. In the absence of oxygen, the production of colored compounds was even smaller in presence of yeasts, as a result of their ability to retain browning products as they form. Because the absence of oxygen not inhibited the formation of intermediate products resulting from oxidation reactions, an alternative oxidation pathway are proposed acting the glyoxylic acid as oxidant. In the usual concentrations of catechin in white wines, the studied reaction of (+)-catechin-glyoxylic acid can contribute significantly to the alteration of the wine color.     

Quantification of glutathione,catechin and caffeic acid in grape juice and wine by a novel ultra-performance liquid chromatography method

This research aimed at the development and validation of an ultra-performance liquid chromatography (UPLC) method for the quantification of glutathione (GSH) in grape juice and in white wine after derivatisation with para-benzoquinone. The phenolic compounds catechin and caffeic acid that occur in white wine and have antioxidant effects, are also quantified in the same analysis. Catechin is the basic monomeric unit of grape and wine tannins and caffeic acid, when esterified with tartaric acid, plays a relevant role in Grape Reaction Product (GRP) formation.     

雪莲果发酵酒的防褐变技术研究

在不影响雪莲果果酒发酵过程和品质的前提下,通过添加抗坏血酸、柠檬酸、蜂蜜、菠萝汁等抗褐变剂来解决雪莲果果酒生产中的褐变问题,得到营养成分损失少、风味佳、色泽鲜亮的雪莲果果酒。结果表明,抑制雪莲果褐变程度的先后顺序为柠檬酸>抗坏血酸>菠萝汁雪莲混合比,蜂蜜在雪莲果酒陈酿期会产生深色物质,不适宜作为雪莲果果酒的抗褐变剂。影响感官的顺序分别为菠萝汁雪莲混合比>抗坏血酸>柠檬酸,最后得出抑制雪莲果酒褐变的最佳组合为抗坏血酸的添加量1.00%,柠檬酸的添加量0.75%,菠萝雪莲混合比为1:4。     

Inhibition of the decrease of volatile esters and terpenes during storage of a white wine and a model wine medium by caffeic acid and gallic acid

Caffeic acid and gallic acid were tested as inhibitors of the decrease of volatile acetate esters, ethyl esters and terpenes during storage of a white wine and a model wine medium. Wine and model wine samples were analysed by SPME along with GC–MS. At t = 0, no effect on the concentration of any volatile was observed as a result of adding each phenolic acid in any of wine or model wine samples. Many esters, such as isoamyl acetate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, and linalool decreased during storage of Debina-white wine for up to 20 months. Caffeic acid and gallic acid at 60 mg/L inhibited the decrease of these volatiles. Isoamyl acetate, ethyl hexanoate and linalool decreased during storage of the model wine medium containing 0, 20 or 40 mg/L SO₂. Caffeic acid and gallic acid inhibited the decrease of three volatiles; SO₂ inhibited the decrease of isoamyl acetate and ethyl hexanoate. In some cases, SO₂ increased the inhibitory action of two phenolic acids. The inhibitory action of caffeic acid and gallic acid was dose dependent in the range 0–60 mg/L. Caffeic acid was active at 7.5 mg/L while gallic acid at 15 mg/L.Present results indicate that caffeic acid and gallic acid may be taken into account as potent inhibitors of the disappearance of aromatic volatile esters and terpenes in wines at concentrations similar to those existing in wines.     

Mechanisms of oxidative browning of wine

Oxidative browning is a long-standing problem in winemaking and sulphur dioxide is the generally used antioxidant to control wine browning. However, concerns over its ability to induce severe allergic reactions have created a great need for its reduction or replacement in recent years. Furthermore, ascorbic acid seems unsuccessful as an alternative antioxidant in winemaking. So a comprehensive understanding of the chemistry of wine browning is essential to study new antioxidant(s) for the protection of wine from browning. The review systematically outlines the mechanisms of wine browning including enzymic and non-enzymic browning happening in winemaking and discusses the central roles performed by iron and copper in the chemistry of wine oxidation. Iron and copper might play a central role in initiating wine non-enzymic browning, and this has important implications in studying antioxidant substitute for sulphur dioxide in wine.     

Role of anthocyanins,polyphenol oxidase and phenols in lychee pericarp browning

Postharvest browning of lychee fruits is investigated in relation to anthocyanins, polyphenol oxidase (PPO) and phenols, using a purified PPO, anthocyanin extract and phenolic extract. Lychee PPO cannot oxidise the degradation of anthocyanins, but the presence of phenolic extract stimulates pigment degradation by PPO, leading to the development of brown pigments. The absorbance at 410 nm of the reaction solution is correlated well with the peel browning index. Pyrogallol, catechol and 4‐methylcatechol are good stimulators, but no action with chlorogenic acid, p‐cresol, resorcinol or tyrosine is observed. A decrease in the ascorbic acid content of lychee pericarp is associated with an increase in the peel browning index, and the addition of ascorbic acid to the reaction mixture exerts a preventive action on the anthocyanin degradation. Data here suggest that anthocyanins, PPO and phenols contribute to lychee pericarp browning involved in anthocyanin–PPO–phenol reactions. © 2000 Society of Chemical Industry