Effect of Phenolic Acid on Antioxidant Activity of Wine and Inhibition of Pectin Methyl Esterase

Antioxidant activity, malolactic fermentation and sensory evaluation of the grape must after fermentation in the presence of gallic acid and coumaric acid, as well as the inhibitory mechanism of gallic acid and coumaric acid on pectin methyl esterase (PME), were investigated. The content of malic acid and lactic acid increased 40.4% and 36.9% compared to the control when commercial pectic enzyme (CPE) was used. The increase in malic acid content was enhanced by 64.8% and 83.4%, compared to the control in the presence of CPE + Gallic acid and CPE + Coumaric acid respectively. Ferric reducing/antioxidant power (FRAP) increased in the samples with added CPE. In addition to an increase in the FRAP, antioxidant capacity was enhanced in the CPE + Gallic acid and CPE + Coumaric acid samples. No significant differences were found in the content of total anthocyanin and in the value of sensory characteristics. The content of total flavanols increased significantly in the samples with added CPE. Lineweaver‐Burk plots of PME, with gallic acid or coumaric acid, indicated that gallic acid and coumaric acid were mixed inhibitors of PME.     

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     

几种酚酸对木聚糖酶活力的影响

采用3,5-二硝基水杨酸法(DNS法)测定酶解后还原糖释放量,研究4种不同酚酸(阿魏酸、对-香豆酸、水杨酸、单宁酸)对木聚糖酶活力的影响。结果表明:阿魏酸、对-香豆酸、水杨酸能提高木聚糖酶活力,当这3种酚酸质量浓度为0.75mg/mL时,酶活力分别提高65.59%、46.21%和12.83%。单宁酸抑制木聚糖酶活性,添加量为0.50mg/mL时,抑制率达37.18%。动力学研究表明:上述4种酚酸均能提高酶与底物的亲和力,对-香豆酸能提高酶反应速度,但单宁酸会使反应速度显著降低。     

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.     

小麦麸皮中酚酸提取方法的研究

研究了酸种类、酸碱浓度、水解时间、水解顺序对小麦麸皮中束缚型酚酸释放量的影响。结果表明,酚酸在小麦麸皮中主要以束缚型形式存在,且肉桂酸类酚酸含量明显高于苯甲酸类酚酸,其中以阿魏酸的含量最高。水解方法对酚酸释放量的影响存在显著差异。采用超声波辅助有机溶剂（甲醇：丙酮：水=7：7：6）提取,酚酸释放量最高的水解条件为：先用2mol／L氢氧化钠室温水解4h,再用2mol／L盐酸于85℃下水解1h,束缚型酚酸总释放量达4719μg／g麸皮。     

甘蔗不同组织中游离态和结合态酚酸的分布及抗氧化活性

为了探讨甘蔗不同组织中酚酸的存在形式,本文利用反相高效液相色谱法(RP-HPLC)对蔗汁、蔗叶及蔗渣三个组织中游离态和结合态的酚酸进行了定性和定量检测分析。结果表明,甘蔗组织中的酚酸主要以结合态形式存在,但其在甘蔗三个组织中的含量和存在形式有差别。甘蔗叶、蔗渣中游离的酚酸含量最高,蔗汁较低。蔗汁、蔗叶及蔗渣中总游离态酚酸含量分别为317.18 mg/kg(干固物),1568.37 mg/kg(干基)及1504.57 mg/kg(干基);总结合态酚酸含量分别为740.32 mg/kg(干固物),2725.41 mg/kg(干基),2452.13 mg/kg(干基)。在蔗汁中,咖啡酸、没食子酸主要以游离态存在,阿魏酸、香豆酸主要以结合态存在,而在蔗叶和蔗渣中,咖啡酸、阿魏酸、香豆酸主要以结合态形式存在。甘蔗不同组织中游离态酚酸的DPPH和ABTS自由基清除活性优于结合态酚酸,不同组织中的游离态酚酸和结合态酚酸含量分别与抗氧化活性呈正相关性。     

Changes of Phenolic Acids During Aging of Organic Wines

Grapes (Vitis vinifera L. origin var: Carignane, Cabernet Sauvignon, Merlot, Grenache, Columbard, and Semillon) were cultivated and processed according to accepted organic agriculture and organic wine techniques. Aged wines (5 years) were evaluated for changes of their phenolic acids. The highest reduction of gallic acid concentrations were determined in Cabernet Sauvignon (24.36 mg/L) and Carignane (16.00 mg/L) wines. The quantities of p-hydroxybenzoic acid decreased mostly in Carignane (22.47 mg/L) and Columbard (20.84 mg/L) wines. The decreases of syringic acid were dominant in Cabernet Sauvignon (2.34 mg/L) and Carignane (1.69 mg/L) wines. In the case of ferulic acid, the highest reduction was determined in Cabernet Sauvignon (3.97 mg/L) wines. The decreases of p-coumaric acid contents were the same and mostly in Merlot (1.06 mg/L) and Grenache (1.035 mg/L) wines. The principal component analyses results demonstrated the relations among aged wines produced from different grape varieties and their phenolic acids. The distribution of data was accumulated into two groups. The first group included total phenols, gallic acid, p-hydroxybenzoic acid, syringic acid, p-coumaric acid, and Merlot/Carignane/Grenache wines. The second one included ferulic acid and Cabernet Sauvignon wine.     

瑰茄浸提及其发酵酒工艺优化及发酵前后有机酸和酚酸的比较

以云南产玫瑰茄干花萼为原料,在单因素试验基础上采用响应面法对玫瑰茄浸提工艺及其发酵酒工艺进行优化,确定玫瑰茄花萼浸提的最佳工艺条件为料液比1∶28（g/mL）、浸提温度84.0℃、浸提时间78min,在此条件下,花青素提取率为（0.060±0.009）%,多酚提取率为（0.201±0.05）%;玫瑰茄酒的最佳发酵工艺条件为发酵温度24.5℃、S4酵母接种量1.6g/L、加糖量22.5%,所得玫瑰茄酒风味独特,其乙醇体积分数为（10.6±0.12）%,花青素质量浓度为（121.25±0.35）mg/L,多酚质量浓度为（629.58±0.22）mg/L,氨基酸种类齐全,组成合理。检测出玫瑰茄浸提液中含有以柠檬酸和木槿酸为主的7种有机酸和以原儿茶酸为主的8种酚酸,玫瑰茄酒中的主要有机酸为乳酸和木槿酸,原儿茶酸仍是其主要的酚酸;在发酵过程中,柠檬酸、羟基柠檬酸和酒石酸含量降低,丙酮酸、乳酸和琥珀酸含量升高;原儿茶酸、龙胆酸和阿魏酸等酚酸含量降低,而没食子酸、香豆酸和丁香酸含量得到了提高。     

Distribution of bound and free phenolic acids in oranges (Citrus sinensis) and Grapefruits (Citrus paradisi)

Free phenolic acids may be the precursors for vinyl phenols and off-flavours formed in citrus products during storage. Quantitative determination of free and bound phenolic acids in fruit parts of grapefruit (Citrus paradisi Macfadyen) and oranges (Citrus sinensis (L) Osbeck) was performed by extraction with ethyl acetate, silica gel column chromatography and HPLC analyses of samples before and after alkaline hydrolysis. The content of free and bound phenolic acids was further determined in juice derived from fruit harvested early, mid and late in season. As found previously for ferulic acid, phenolic acids occur mainly in bound forms in grapefruits and oranges. In both fruits the peels contained the major portion of cinnamic acids compared with the endocarp, and the flavedo was richer in hydroxycinnamic acids than the albedo. In most cases, hydroxycinnamic acid content was in the following order: ferulic acid>sinapic acid>coumaric acid>caffeic acid. Results showed that the content of bound cinnamic acids was unchanged or slightly elevated from early to late season. However, the content of free acids was reduced during that period.     

桑葚、甘蔗糖蜜多酚的成分鉴定及其复配物的抗氧化活性

为探索酚类提取物及其复配物的协同增效作用,以桑葚和甘蔗糖蜜多酚作为研究对象,分别测定其总酚、黄酮含量及酚类组成,基于单一提取物的总酚含量按一定配比制得复配物,评价抗氧化活性。结果表明,桑葚游离多酚（MFP）占桑葚总酚含量的90.3%,为677.62 mg没食子酸当量（Gallic Acid Equivalent,GAE）/100 g,黄酮含量为736.65 mg芦丁当量（Rutinum Equivalent,RE）/100 g,共检测出原儿茶酸、3,4-二羟基苯丙酸、咖啡酸、丁香酸、对香豆酸、阿魏酸、矢车菊素3-O-葡萄糖苷和芦丁8种多酚物质,其中矢车菊素3-O-葡萄糖苷含量占92.6%。甘蔗糖蜜多酚（SMP）总酚含量为339.69 mg GAE/100 g,总黄酮含量为314.61 mg RE/100 g,主要单体包括没食子酸、原儿茶酸、绿原酸、咖啡酸、丁香酸、对香豆酸、阿魏酸、芦丁和表儿茶素9种多酚物质。在0~10 mg/mL的浓度范围内SMP、MFP及其复配物具有良好的抗氧化活性且呈现量效关系。同时,两种复配物的抗氧化活性优于SMP和MFP,其中中效原理计算复配物DPPH自由基清除能力的0.25 IC50、0.5 IC50、0.75 IC50、1 IC50、1.25 IC50、1.5 IC50的联合作用指数CI分别为0.73、0.85、0.94、0.91、0.89和0.90,均小于1,表明桑葚和甘蔗糖蜜多酚复配物具有协同抗氧化作用。     

地参发酵酒的工艺优化及品质分析

目的：以新鲜的地参为原料,研究地参发酵酒的最佳工艺。方法：采用单因素实验和Box-Behnken响应面优化地参发酵酒的工艺条件,以酒精度及感官评分为响应值,考察发酵温度、酵母接种量和初始糖度对发酵酒的影响,采用UPLC法对地参发酵酒的酚酸类物质进行了分析。结果：地参发酵酒最佳工艺条件为：酵母接种量为5.1%,初始糖度为22.8%,发酵温度为26℃,发酵时间为9 d。在此条件地参发酵酒酒精度达到11.23%vol,感官评分为85.50分,多糖、总酚、总酸和总黄酮含量分别为6.54 g/L、384.31 mg/L、20.67 g/L和204.59 mg/L。地参发酵酒的ABTS+、DPPH和对羟基自由基的清除率分别为90.53%、81.51%和55.86%,说明其具有一定的抗氧化活性;地参发酵酒含有没食子酸、丹参素、原儿茶酸、对羟基苯甲酸和咖啡酸5种酚酸类物质,其中没食子酸含量最高（11.20 mg/L）。结论：优化工艺后的地参发酵酒色泽呈橘黄色,澄清透明,酒体醇厚丰满,不仅具有独特的地参酒风味,同时较好的保留了地参发酵酒多酚等活性成分。     

Determination of Phenolic Compounds in Strawberries (Fragaria ananassa Duch) by High Performance Liquid Chromatography with Diode Array Detection

This paper describes a method for simultaneous identification and quantification of phenolic compounds in strawberries followed by a reversed-phase high performance liquid chromatography (HPLC) with diode array detection. The studied phenolics were flavonoids (flavonols: quercentin, rutin, and kaempferol; flavanols: catechin and epicatechin; anthocyanidins: cyanidin and pelargonidin) and phenolic acids (hydroxybenzoic acid derivatives: gallic and ellagic acids; hydroxycinnamic acid derivatives: ferulic, coumaric, and cinnamic acids). The mobile phase consisted in a gradient prepared from formic acid in water (2 %, pH 3) and formic acid in methanol (2 %, pH 3), flow rate 0.7 mL min^?1 at 25 °C. Analyses were performed, using methanol as extractant, before and after acid hydrolysis with the aim of determining free and conjugated phenolic compounds in strawberries. The acid hydrolysis conditions (6 mol L^?1 HCl, 50 min at 90 °C) were shown to be suitable both for phenolic standards and strawberry extracts. Method validation, using phenolic standard solutions, included: linearity study, limits of detection and quantification, and calibration and analytical sensitivity quantifications. Precision and accuracy were studied in strawberry extracts. The results indicate that the developed method was linear, sensible, precise, and accurate, and the convenience of methanol can substitute acetonitrile as the most commonly used solvent in HPLC. The method was employed for knowing the phenolic profile in seven strawberry cultivars from Italy and Argentina, and besides, total phenolic content was analyzed by the Folin–Ciocalteu method; the total antioxidant activity was investigated using the ABTS method. Good correlations were observed among latter parameters, and total phenolics were obtained as the sum of each phenolic compound analyzed by photodiode array detection-HPLC.     

两类紫云英苗菜生长过程中酚类物质及其抗氧化活性的变化

紫云英营养价值高,常做绿肥、牧草使用,种植效益较低。为拓宽紫云英资源化利用渠道,选取湘紫1号、皖紫1号两类紫云英种子水培开发苗菜,以土培紫云英成熟茎叶为对照,对比分析两种种质酚类物质组成差异和发芽8~14 d的变化,以及酚类物质与抗氧化性之间的相关性。结果发现,两类紫云英苗菜生长过程中总酚、总黄酮含量以及抗氧化能力均呈上升趋势;皖紫1号苗菜酚类物质含量以及抗氧化能力均优于湘紫1号。发芽14 d的皖紫1号苗菜总酚（7.31 mg/g dw）、总黄酮（5.86 mg/g dw）含量高且抗氧化性强,共检测出12种酚类化合物,比土培成熟茎叶多检测出没食子酸、阿魏酸、香草酸、水杨酸、丁香酸5种酚类物质。其优势成分为山奈酚（12.86±0.34 mg/g）、芹菜素（6.38±0.17 mg/g）、槲皮素（5.36±0.04 mg/g）、对香豆酸（4.59±0.13 mg/g）、没食子酸（3.01±0.11 mg/g）、木犀草素（3.00±0.02 mg/g）和阿魏酸（2.35±0.29 mg/g）。其中,没食子酸含量为发芽14 d湘紫1号苗菜13倍,对香豆酸含量达到土培成熟茎叶的33倍。本文为紫云英苗菜选种、育苗提供了初步理论支撑和相关参数参考,建议增强对紫云英水培开发苗菜和其酚类资源的关注和开发。     

High-added-value antioxidants obtained from the degradation of wine phenolics by Lactobacillus plantarum

Disposal of the waste from wine production has long been a problem for wineries, mainly because of the presence of phenolic compounds. In this study, we analyzed the antimicrobial activities of 10 wine phenolic compounds against Lactobacillus plantarum strains. Inhibition increased in this order: catechin = gallic acid < epicatechin = salicylic acid < methyl gallate = caffeic acid < ferulic acid = tryptophol < p-coumaric acid. The obtained results indicated that L. plantarum is able to grow in the presence of high concentrations of some wine phenolic compounds. Of the 10 compounds analyzed, only the hydroxycinnamic acids, gallic acid, and methyl gallate were metabolized by the four L. plantarum strains studied. Results also revealed that 4-vinylphenol and 4-vinylguaiacol are originated from p-coumaric and ferulic acids. These phenolic compounds are valuable intermediates in the biotechnological production of new fragrances. In addition, gallic acid and its ester, methyl gallate, are metabolized to produce the powerful antioxidant pyrogallol. Therefore, it might be possible to use L. plantarum strains to obtain high-added-value antioxidants from the degradation of phenolic compounds found in wine wastes.     

Strengthening the texture of dried guava slice by infiltration of phenolic compounds

Phenol–pectin interaction was highlighted in plant texture maintenance during thermal processing. However, neither application nor significantly involved phenolic compounds other than ferulic acid have been reported. The aim of this study is to evaluate the contribution of this crosslink in strengthening the texture of guava slices with six phenolic compounds during processing. Results showed that samples treated with phenolics bearing a carboxyl group exhibited significantly higher hardness than control samples. Further pectin fractionation analysis and binding capacity tests in an artificial model system proved the existence of a higher ratio of hard pectin and greater binding capacity in phenolic treated samples. Sephadex G-75 purification and observation through fluorescence microscope and SEM confirmed the existence of phenol–pectin complex. Contribution of binding capacity to strengthen hardness was found highest in gallic acid treated samples, followed by those treated with ferulic acid, caffeic acid, coumaric acid, cinnamic acid or catechin. FRAP reducing power and DPPH scavenging ability showed the similar tendency. These results indicated that phenolic infiltration might improve the texture and antioxidant capacity of processed guava slices through phenol–pectin interaction.     

小麦酚酸提取工艺优化及产区与品种差异对酚酸含量的影响

研究NaOH浓度、液料比、乙酸乙酯萃取时间和萃取次数对小麦籽粒中酚酸提取量的影响,并优化提取条件;运用高效液相色谱-质谱联用法分析不同产区主栽小麦品种差异对酚酸含量的影响。结果表明：NaOH浓度、液料比、乙酸乙酯萃取时间和萃取次数对小麦籽粒中酚酸提取量影响显著,经响应面优化获得小麦籽粒中酚酸提取条件为：NaOH溶液浓度1.56 mol/L、液料比15.53∶1（mL/g）、萃取时间17.33 min、萃取2 次。在此提取条件下,小麦籽粒中酚酸提取量达到1 055.99 mg/kg。小麦中主要有9 种酚酸,分别为没食子酸、原儿茶酸、4-羟基苯甲酸、香草酸、咖啡酸、丁香酸、p-香豆酸、芥子酸和阿魏酸,其中阿魏酸为主要酚酸,占总酚酸的73.07%～89.01%。江淮麦区宁麦14中总酚酸含量最高,达1 001.12 mg/kg,与该产区的保麦6号、淮麦33有显著性差异;黄淮麦区的新麦26中总酚酸含量最高,为1 016.03 mg/kg,与该产区的矮抗58、百农207有显著性差异。由此可见,不同产区主栽小麦品种的差异对酚酸含量的影响极大。     

苯丙氨酸-肌酐模型反应体系中甘蔗糖蜜酚酸单体对PhIP的抑制作用

该研究探讨了模型反应体系中甘蔗糖蜜含有的阿魏酸和香草酸对2-氨基-1-甲基-6-苯基-咪唑[4,5-b]吡啶(Ph IP)的抑制作用。实验通过糖蜜净化处理方法去除糖蜜中的胶体、灰分和重金属等物质,得到糖蜜粗提物,建立没食子酸标准曲线,测定糖蜜提取物中多酚含量。通过UPLC-MS对糖蜜提取物进行分析,确定糖蜜提取物中含有的酚酸种类。将酚酸单体分别加入到模型反应(苯丙氨酸和肌酐)体系中,用UPLC-MS系统分析模型反应中Ph IP的变化。结果发现,糖蜜提取物中多酚含量多达3.58 mg/g,通过和酚酸标准品对照,发现糖蜜提取物中含有阿魏酸和香草酸。在模型反应体系中,随着阿魏酸和香草酸浓度的增加,模型反应中苯丙氨酸含量和Ph IP的生成量均先逐渐减少后趋于平稳,当阿魏酸溶液浓度达到2.33×10-7 g/m L时,对Ph IP的抑制效果最佳,总体抑制率为76.67%;当香草酸溶液浓度达到2.02×10-7 g/m L时,对Ph IP的抑制效果最佳,总体抑制率为77.43%。综上,甘蔗糖蜜中含有的阿魏酸和香草酸单体在模型反应体系中均对Ph IP有较强的抑制作用,为后续对Ph IP抑制物的研究提供了基础。     

Effect of phenolic acids on glucose and organic acid metabolism by lactic acid bacteria from wine

The influence of phenolic (p-coumaric, caffeic, ferulic, gallic and protocatechuic) acids on glucose and organic acid metabolism by two strains of wine lactic acid bacteria (Oenococcus oeni VF and Lactobacillus hilgardii 5) was investigated. Cultures were grown in modified MRS medium supplemented with different phenolic acids. Cellular growth was monitored and metabolite concentrations were determined by HPLC-RI. Despite the strong inhibitory effect of most tested phenolic acids on the growth of O. oeni VF, the malolactic activity of this strain was not considerably affected by these compounds. While less affected in its growth, the capacity of L. hilgardii 5 to degrade malic acid was clearly diminished. Except for gallic acid, the addition of phenolic acids delayed the metabolism of glucose and citric acid in both strains tested. It was also found that the presence of hydroxycinnamic acids (p-coumaric, caffeic and ferulic) increased the yield of lactic and acetic acid production from glucose by O. oeni VF and not by L. hilgardii 5. The results show that important oenological characteristics of wine lactic acid bacteria, such as the malolactic activity and the production of volatile organic acids, may be differently affected by the presence of phenolic acids, depending on the bacterial species or strain.     

Pomological features, nutritional quality, polyphenol content analysis, and antioxidant properties of domesticated and 3 wild ecotype forms of raspberries (Rubus idaeus L.)

Abstract: The raspberry (Rubus idaeus L.) is an economically important berry crop that contains many phenolic compounds with potential health benefits. In this study, important pomological features, including nutrient content and antioxidant properties, of a domesticated and 3 wild (Yayla, Yavuzlar, and Yedigöl) raspberry fruits were evaluated. Also, the amount of total phenolics and flavonoids in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were calculated as gallic acid equivalents (GAEs) and quercetin equivalents (QE). The highest phenolic compounds were found in wild Yayla ecotype (26.66 ± 3.26 GAE/mg extract). Whilst, the highest flavonoids were determined in wild Yedigöl ecotype (6.09 ± 1.21 QA/mg extract). The antioxidant activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were investigated as trolox equivalents using different in vitro assays including DPPH^?, ABTS^?+, DMPD^?+, and O^??₂ radical scavenging activities, H₂O₂ scavenging activity, ferric (Fe³⁺) and cupric ions (Cu²⁺) reducing abilities, ferrous ions (Fe²⁺) chelating activity. In addition, quantitative amounts of caffeic acid, ferulic acid, syringic acid, ellagic acid, quercetin, α‐tocopherol, pyrogallol, p‐hydroxybenzoic acid, vanillin, p‐coumaric acid, gallic acid, and ascorbic acid in lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits were detected by high‐performance liquid chromatography and tandem mass spectrometry (LC‐MS‐MS). The results clearly show that p‐coumaric acid is the main phenolic acid responsible for the antioxidant and radical scavenging activity of lyophilized aqueous extracts of domesticated and wild ecotypes of raspberry fruits.     

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.