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At least 109 records · Page 6Linked to original sources
PubMed2006

Ochratoxin A occurrence and formation in Portuguese wine grapes at various stages of maturation.

A total of 93 Portuguese grape samples destined for wine production were examined for the presence of ochratoxin A (OTA) and the OTA producing fungi Aspergillus carbonarius and A. niger aggregate. Samples came from 11 vineyards from four winemaking regions in the North and South of the Portuguese mainland, during the harvest seasons of 2001, 2002 and 2003. Grapes were examined at 3 maturation stages, from setting to the harvesting period, to evaluate when contamination with OTA producing fungi and OTA synthesis occur. The detection of fungi in grape samples was made by plating methods with and without surface disinfection. OTA was formed by 14% of the 650 isolates tested. Most of the OTA producing strains (96%) were isolated at harvest time. At this stage, the percentage of grape samples with OTA producing strains detected without surface disinfection was 56%. With surface disinfection, A. carbonarius was isolated from 10% of the samples. OTA was detected in grapes at the 3 maturation stages. The average OTA concentrations in 60 samples at pea berry (28 samples), early veraison (22 samples) and ripe berry (20 samples) were 263, 149 and 35 ng/kg, respectively. Experiments with an A. carbonarius strain demonstrated that OTA production differs significantly with the composition of the berries at different maturation stages (P<0.001), with a mean value of OTA production at pea berry, early veraison and ripe berry of 3402, 1530 and 22 mug/kg, respectively. The production of OTA by A. carbonarius was correlated positively and negatively with the total acidity of grapes (r(s)=0.855, P<0.001) and reducing sugars content (r(s)=-0.835, P<0.001), respectively. Our data demonstrate that OTA synthesis in grapes occurs since early maturation stages.

Aspergillus↗
PubMed2006

Detection and quantification of Erysiphe necator DNA in wine grapes and resultant must and juice.

Powdery mildew of grapevines is difficult to assess visually at the weighbridge, particularly in large consignments of machine-harvested fruit. To facilitate accurate methods for the detection and quantification of the disease in grape samples obtained from both the vineyard and winery, we developed a DNA probe for the pathogen Erysiphe necator. The E. necator-specific 450 bp DNA fragment pEnA1, targets highly repetitive sequences and was isolated from a partial genomic library. In screening for species specificity, clone pEnA1 was used in slot-blot hybridization and detected E. necator DNA from grapes and resultant must and juice, but not from clarified juice and wine. The detection threshold was approximately 50 pg of E. necator DNA per 100 ng total DNA of grape sample and was equivalent to 1-5% of a grape bunch visually affected by powdery mildew. Disease severity, expressed as the percentage of surface area of a bunch with powdery mildew, and E. necator DNA content were highly correlated, r2=0.955, P<0.001. The DNA-based hybridization assay has the potential to predict the severity of powdery mildew in grape samples from the vineyard and in must and juice samples at the winery. The DNA sequence of clone pEnA1 was used to design species-specific primers, the results maintaining the same specificity patterns observed in the initial hybridization assays. The PCR-based assay was sensitive enough to detect approximately 1 pg DNA, being equivalent to 1 conidium per sample. This is the first report to date of the detection of all known phenetic groups of E. necator DNA and of the quantification of DNA from grape samples at the winery. Accurate information on the extent of powdery mildew contamination of grape lots would enable wineries to make more informed decisions about the use of fruit and must.

Ascomycota↗
PubMed2001

Value of high-performance liquid chromatographic analysis of anthocyanins in the differentiation of red grape cultivars and red wines made from them.

A HPLC method that allows the separation of several anthocyanins present in red grapes and red wines, using a linear gradient of acetonitrile in water at pH 1.3, using perchloric acid as an acid modifier, is described. Data clearly show that the anthocyanins profile of red grapes may be complex, but quite different for each cultivar studied. Thus, those molecules may be used as chemotaxonomic markers for classifying red grape cultivars. However, the anthocyanin profile of red wines clearly differs from that presented by grapes employed in making it, because red wine contains a higher relative amount of malvidin-3-O-glucoside than grapes, and the relative amount of other anthocyanins in wines is usually lower than in grapes. Therefore, the use of anthocyanins present in wines to determine the grape cultivar used for winemaking needs a careful evaluation of the influence of different technological procedures on the anthocyanins fingerprint.

Anthocyanins↗
PubMed1999

Quantitative determination of 2-methoxy-3-isobutylpyrazine in red wines and grapes of Bordeaux using a stable isotope dilution assay.

Quantitative analysis of 2-methoxy-3-isobutylpyrazine (MIBP) in grapes and wines was developed, using a stable isotope dilution assay. This was applied to red grapes and wines from the Bordeaux region. The grapes and the wines of the 1995 and 1996 vintages came from the three most frequently used varieties of the region, Merlot, Cabernet Franc and Cabernet Sauvignon. The wines made from Cabernet Sauvignon grapes exhibited levels of MIBP (mean concentration, 12 ng l-1 for 1996 vintage and 13 ng l-1 for 1995 vintage) close to or higher than its odour threshold in wines (10 ng l-1) and slightly higher than the amounts found in the Merlot wines (mean concentration, 8 ng l-1 for 1996 vintage and 4 ng l-1 for 1995 vintage), especially those of the 1996 vintage. The variation in the levels of MIBP in grape samples and in their corresponding wines was monitored at four different stages towards the end of maturation. MIBP was present in all grapes and wines analysed, even in surmaturation. A linear trend was observed between grapes and wines of the three cultivars during maturation.

Deuterium↗
PubMed1996

Contribution of phenols, quinones and reactive oxygen species to the mutagenicity of white grape juice in the Ames test.

The purpose of this study was to evaluate the role of phenols, quinones and reactive oxygen species in the mutagenicity of white grape juice in the Ames mutagenicity test. Mutagenicity was markedly suppressed by reduced glutathione but was not influenced by superoxide dismutase or catalase. In the presence of grape polyphenol oxidase, the mutagenicity of grape juice was markedly increased. When hepatic cytosol from Aroclor 1254-induced rats, supplemented with a reduced nicotinamide adenine dinucleotide phosphate-generating system. served as an activation system, an increase in the mutagenicity of grape juice was observed. The cytosol-induced mutagenicity of grape juice was attenuated in the presence of superoxide dismutase, catalase and glutathione. It is concluded that polyphenol oxidase-catalysed oxidation of phenolic compounds generates genotoxic species that are, at least partly, responsible for the mutagenicity of grape juice. In the presence of hepatic cytosol, one-electron reduction of grape juice quinones leads to the production of reactive oxygen species resulting in an increase in the mutagenic response.

Animals↗
PubMed1999

Adult onset grape hypersensitivity causing life threatening anaphylaxis.

BACKGROUND: Adverse reactions to foods are encountered much less frequently in adults than in the children. Adult onset hypersensitivity to grapes has not been previously reported. OBJECTIVE: Evaluation of a case of anaphylaxis that occurred as a result of the consumption of white grapes (Vitis vinifera). METHODS AND RESULTS: A 28-year-old woman experienced generalized urticaria, facial/oropharyngeal angioedema, and dizziness after eating a bunch of white grapes. She was treated in an emergency room for anaphylaxis. Previously, she had experienced two similar episodes after eating white grapes. The grape prick skin tests were strongly positive forming a pseudopod type reaction. The total serum IgE was 1918 ng/mL. The grape-specific serum IgE was weakly positive by the modified RAST and negative in the Pharmacia-Upjohn Cap System. CONCLUSION: Hypersensitivity to a commonly consumed fruit such as grapes can develop late in life causing a near-fatal anaphylaxis.

Adult↗
PubMed2002

Red grape juice inhibits iron availability: application of an in vitro digestion/caco-2 cell model.

Adequate bioavailable Fe intake is essential for optimal growth and intellectual development of infants and children. Fruit juices are nutritious and popular drinks for infants and children and are known to contain Fe uptake inhibitors (e.g., polyphenolic compounds) and a dominant promoter, ascorbic acid. Ascorbic acid is naturally present in fruit juices and is added during processing to almost all juices found in supermarkets. With these facts taken into account, an in vitro digestion/Caco-2 cell culture model was developed to compare the effects of apple, pear, white grape, red grape, prune, grapefruir, and orange juices on iron bioavailability. In two series of experiments, juices from a local supermarket were combined with FeCl(3) or commercial infant cereal fortified with elemental iron and subject to simulated gastric and intestinal digestion. Caco-2 cell ferritin formation in response to exposure to the digests served as the measure of Fe uptake. The pear, apple, grapefruit, orange, and white grape juice significantly increased Fe bioavailability from FeCl(3). For the infant cereal studies, the apple, orange, pear, and white grape juices increased the Fe bioavailability of the infant cereal. In contrast, the red grape juice and prune juice had profound inhibitory effects on iron bioavailability. These inhibitory effects were likely due to high levels of polyphenolic compounds that bind and thereby prevent absorption of soluble Fe. These inhibitory compounds appeared to counteract the promotional effects of ascorbic acid as they were in considerable molar excess relative to ascorbic acid and Fe in the digest. From a nutritional standpoint, the results suggest that individuals in need of optimal Fe absorption should avoid red grape and prune juice or at least vary the types of juices consumed. Alternatively, individuals seeking to limit Fe uptake (e.g., hemochromatitics and astronauts) may be able to utilize red grape or prune juice as effective inhibitors of Fe uptake. Consumers should be aware that the compounds that inhibit Fe availability are also linked to anticancer benefits; thus, a dietary balance of the above juices may be optimal.

Beverages↗
PubMed2003

Characterization of anthocyanins in grape juices by ion trap liquid chromatography-mass spectrometry.

A reverse phase HPLC and electrospray interface with ion trap mass spectrometer method was developed for the characterization of anthocyanins in Concord, Rubired, and Salvador grape juices. Rubired and Salvador grapes are hybrids from Vitis vinifera and Vitis rupestris. Concord grape is a grape from the native American cultivar Vitis labrusca. Individual anthocyanins in these three varieties were identified on the basis of UV-vis and MS spectra and further elucidated by MS/MS spectra. Anthocyanins in Salvador and Concord grapes were 3-O-glucosides, 3-O-(6' '-O-p-coumaroyl)glucosides, 3-O-(6' '-O-p-acetyl)glucosides, 3,5-O-diglucosides, and 3-O-(6' '-O-p-coumaroyl)-5-O-diglucosides of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Vitisin B was detected in Salvador grape juice. Anthocyanins in Rubired grape juice were primarily anthocyanin diglucosides: peonidin 3,5-O-diglucoside, malvidin 3,5-O-diglucoside, peonidin 3-O-(6' '-O-p-coumaroyl)-5-O-diglucoside, and malvidin 3-O-(6' '-O-p-coumaroyl)-5-O-diglucoside are the four major anthocyanins. The presence of pelargonidin 3-O-glucoside, not previously reported, has been established for the first time in all three juices.

Anthocyanins↗
PubMed2004

Anthocyanin quantification and radical scavenging capacity of Concord, Norton, and Marechal Foch grapes and wines.

The anthocyanin content and the radical scavenging capacity of three non-Vitis vinifera grapes (Marechal Foch, Norton, and Concord varieties) were determined. Analyses of anthocyanins in the skin (S) and wine (W) of these grape varieties were performed by spectrophotometry, HPLC with electrochemical detection, and matrix-assisted laser desorption ionization (MALDI). The total anthocyanin contents of S samples were 258 +/- 37 mg/100 g of wet weight for Foch, 888 +/- 78 mg/100 g for Norton, and 326 +/- 5.9 mg/100 g for Concord grapes. The malvidin 3,5-diglucoside content quantified by HPLC indicated that Norton S had the highest amount of the compound (327 +/- 110 mg/100 g). The MALDI mass spectrometric analysis indicated an abundance of malvidin glucosides in W of Foch grapes and in S and W of Norton grapes and of cyanidin aglycon in S and W of Concord grapes. S samples were subjected to a radical scavenging capacity test using the 2,2-diphenyl-1-picrylhydrazyl radical and compared to Trolox. The radical scavenging capacity for Foch S was 0.78 mM Trolox equiv, that of Concord S, 0.80 Trolox equiv, and that of Norton S was highest at 0.95 Trolox equiv. The higher concentrations of malvidin 3,5-diglucoside in S of grape varieties were associated with greater radical scavenging capacity.

Anthocyanins↗
PubMed2005

Etiology of UV-C-induced browning in var. Superior white table grapes.

White table grapes, var. Superior, were treated with UV-C light after harvest to increase stilbenes concentration, especially trans-resveratrol (RES), because this may be of relevance to the health-promoting properties assigned to these compounds. However, irradiated grapes also developed some browning on the surface on the third day of storage at 22 degrees C, with the subsequent detriment in the sensorial quality of the fruit. Possible causes for browning development during storage were investigated. The phenolic-related oxidative enzymes, polyphenol oxidase (PPO) and peroxidase (POD), were not specifically activated, and no new isoforms appeared upon UV-C treatment. UV-treated grapes had lower content of chlorophyll b than control grapes on the fourth day of storage, concomitant with the increase of pheophytins (chlorophyll degradation derived compounds). Microscopy data showed lower fluorescence emission in chloroplasts from the UV-treated samples, which may explain the decrease of chlorophylls content in the corresponding grape berries extracts. In addition, microscopy images showed cell wall thickening in the skin tissue of UV-treated grapes which could be considered as a general wound response in plant tissues. These results suggest that the development of browning in Superior white grapes after UV-C treatment is not closely related with the evolution of oxidative enzymes during storage and may be mainly due to the decrease of chlorophylls content.

Catechol Oxidase↗
PubMed2006

Quantification of selected aroma-active compounds in Pinot noir wines from different grape maturities.

Effect of grape maturity on aroma-active compounds in Pinot noir wine was investigated using stir bar sorptive extraction-gas chromatograph-mass spectrometry (SBSE-GC-MS). High correlation coefficient (> 0.95) and low standard deviation (< 10%) were obtained for all aroma-active compounds of interest. Two vintages of Pinot noir wines with three different grape maturities each were analyzed. Statistical analysis showed that both grape maturity and growing year significantly affected the aroma composition of the final wine. Analysis of wine samples from the same vintage indicated that grape maturity could affect aroma compounds in different ways, based on their biochemical formation in the wines. For most short-chain fatty acid esters, there were no obvious trends with grape maturity, however, the concentrations of ethyl 2-methylpropanoate and ethyl 3-methylbutanoate consistently decreased with grape maturity. The decreasing trend was also observed for other esters including ethyl cinnamate, ethyl dihydroxycinnamate, and ethyl anthranilate, with the exception of ethyl vanillate, while C13 norisoprenoids, monoterpenes, and guaiacols had increasing trends with grape maturation.

Alcohols↗
PubMed2006

Metabolite profiling of grape: Flavonols and anthocyanins.

Flavonols are products of the flavonoid biosynthetic pathway, which also give rise to anthocyanins and condensed tannins in grapes. We investigated their presence in the berry skins of 91 grape varieties (Vitis vinifera L.), in order to produce a classification based on the flavonol profile. The presence of laricitrin 3-O-galactoside and syringetin 3-O-galactoside in red grapes is reported here for the first time. In red grapes, the main flavonol was quercetin (mean = 43.99%), followed by myricetin (36.81%), kaempferol (6.43%), laricitrin (5.65%), isorhamnetin (3.89%), and syringetin (3.22%). In white grapes, the main flavonol was quercetin (mean = 81.35%), followed by kaempferol (16.91%) and isorhamnetin (1.74%). The delphinidin-like flavonols myricetin, laricitrin, and syringetin were missing in all white varieties, indicating that the enzyme flavonoid 3',5'-hydroxylase is not expressed in white grape varieties. The pattern of expression of flavonols and anthocyanins in red grapes was compared, in order to gain information on the substrate specificity of enzymes involved in flavonoid biosynthesis.

Anthocyanins↗
PubMed1999

Herbicide residues in grapes and wine.

The persistence of several common herbicides from grapes to wine has been studied. Shiraz, Tarrango and Doradillo grapes were separately sprayed with either norflurazon, oxyfluorfen, oxadiazon or trifluralin-persistent herbicides commonly used for weed control in vineyards. The dissipation of the herbicides from the grapes was followed for 28 days following treatment. Results showed that norflurazon was the most persist herbicide although there were detectable residues of all the herbicides on both red and white grapes at the end of the study period. The penetration of herbicides into the flesh of the grapes was found to be significantly greater for white grapes than for red grapes. Small-lot winemaking experiments showed that norflurazon persisted at levels close to the initial concentration through vinification and into the finished wine. The other herbicides degraded, essentially via first-order kinetics, within the period of "first fermentation" and had largely disappeared after 28 days. The use of charcoal together with filter pads, or with diatomaceous earth was shown to be very effective in removing herbicide residues from the wine. A 5% charcoal filter removed more than 96% of the norflurazon persisting in the treated wine.

Herbicides↗
PubMed2003

Polyphenolics in grape seeds-biochemistry and functionality.

Grape seeds are waste products of the winery and grape juice industry. These seeds contain lipid, protein, carbohydrates, and 5-8% polyphenols depending on the variety. Polyphenols in grape seeds are mainly flavonoids, including gallic acid, the monomeric flavan-3-ols catechin, epicatechin, gallocatechin, epigallocatechin, and epicatechin 3-O-gallate, and procyanidin dimers, trimers, and more highly polymerized procyanidins. Grape seed extract is known as a powerful antioxidant that protects the body from premature aging, disease, and decay. Grape seeds contains mainly phenols such as proanthocyanidins (oligomeric proanthocyanidins). Scientific studies have shown that the antioxidant power of proanthocyanidins is 20 times greater than vitamin E and 50 times greater than vitamin C. Extensive research suggests that grape seed extract is beneficial in many areas of health because of its antioxidant effect to bond with collagen, promoting youthful skin, cell health, elasticity, and flexibility. Other studies have shown that proanthocyanidins help to protect the body from sun damage, to improve vision, to improve flexibility in joints, arteries, and body tissues such as the heart, and to improve blood circulation by strengthening capillaries, arteries, and veins. The most abundant phenolic compounds isolated from grape seed are catechins, epicatechin, procyanidin, and some dimers and trimers.

Antioxidants↗
PubMed2005

Grape powder polyphenols attenuate atherosclerosis development in apolipoprotein E deficient (E0) mice and reduce macrophage atherogenicity.

The beneficial health effects of red wine have been attributed to the antioxidant activity of its polyphenols. The present study investigated the effects of a standardized freeze-dried powder made from fresh grapes, rich in grape-specific polyphenols and free of alcohol, on oxidative stress, atherogenicity of macrophages, and the development of atherosclerotic lesions in apolipoprotein E deficient (E(0)) mice. Thirty E(0) mice were assigned to 3 groups. Mice consumed water alone (control), 150 mug total polyphenols/d in the form of grape powder (grape powder), or the equivalent amount of glucose and fructose (placebo) in drinking water for 10 wk. Consumption of grape powder reduced the atherosclerotic lesion area by 41% (P < 0.0002) compared to the control or placebo mice. The antiatherosclerotic effect was at least partly due to a significant 8% reduction in serum oxidative stress, an up to 22% increase in serum antioxidant capacity, a significant 33% reduction in macrophage uptake of oxidized LDL, and a 25% decrease in macrophage-mediated oxidation of LDL relative to controls. Grape powder directly protected both plasma LDL and macrophages from oxidative stress in vitro. We conclude that polyphenols from fresh grape powder directly affect macrophage atherogenicity by reducing macrophage-mediated oxidation of LDL and cellular uptake of oxidized LDL. Both of these processes can eventually reduce macrophage cholesterol accumulation and foam cell formation and hence attenuate atherosclerosis development.

Animals↗
PubMed2002

Cardioprotection with grapes.

Epidemiologic studies suggest that mild-to-moderate wine consumption is associated with a reduced incidence of mortality and morbidity from coronary heart disease. Because wines are produced from grapes, this study was done to determine whether the grapes were equally cardioprotective. Sprague-Dawley male rats were given (orally) standardized grape extract (SGE) (obtained from the California Table Grape Commission, Fresno, CA, U.S.A.) (50, 100, or 200 mg/kg body weight per day) for 3 weeks. Time-matched control experiments were performed by feeding the animals 45 microg/100 g of glucose plus 45 microg/100 g of fructose per day for 3 weeks. After 21 days, rats were killed and the hearts excised and perfused via working mode. Hearts were made ischemic for 30 min followed by 2 h of reperfusion. At 100 mg/kg and at 200 mg/kg, grapes provided significant cardioprotection as evidenced by improved postischemic ventricular recovery (aortic flow, developed pressure, the maximum first derivative of the developed pressure) and reduced amount of myocardial infarction. There were no differences in results between the two groups (100 mg/kg versus 200 mg/kg). No cardioprotection was apparent when rats were given grape samples at a dose of 50 mg/100 g/d. SGE reduced the malonaldehyde content of the heart, indicating reduction of oxidative stress during ischemia and reperfusion. In vitro studies demonstrated that the SGE could directly scavenge superoxide and hydroxyl radicals that are formed in the ischemic reperfused myocardium. The results demonstrate that the hearts of the rats fed SGE are resistant to myocardial ischemia reperfusion injury, suggesting a cardioprotective role of grapes.

Animals↗
PubMed1976

Virus inactivation by grapes and wines.

Infusions and extracts of different grapes inactivated poliovirus; agents responsible for this property resided in the skin of the grape. Commercial grape juice at both natural and neutral pH inactivate various enteric viruses and herpes simplex virus; a 1,000-fold reduction in poliovirus infectivity occurred after incubation with grape juice, pH 7.0, for 24 h at 4 degrees C. A variety of wines were antiviral but to a lesser extent than grape juice; red wines were more antiviral than white. Antiviral activity was demonstrable in fractions of grape juice varying in molecular weight from less than 1,000 to greater than 30,000 as determined by membrane filtration. Some restoration of poliovirus infectivity from virus-grape juice complexes was achieved with 1% gelatin, 0.1% Tween 80, 0.5% polyvinyl pyrrolidone, and 0.5% polyethylene glycol.

Antiviral Agents↗
PubMed2003

Bioavailability of anthocyanidin-3-glucosides following consumption of red wine and red grape juice.

Pharmacokinetic parameters and the bioavailability of several dietary anthocyanins following consumption of red wine and red grape juice were compared in nine healthy volunteers. They were given a single oral dose of either 400 mL of red wine (279.6 mg total anthocyanins) or 400 mL of red grape juice (283.5 mg total anthocyanins). Within 7 h, the urinary excretion of total anthocyanins was 0.23 and 0.18% of the administered dose following red grape juice and red wine ingestion, respectively. Pharmacokinetic parameters derived from plasma and urine concentrations exhibited higher variability after ingestion of red grape juice. Compared to red grape juice anthocyanins, the relative bioavailability of red wine anthocyanins was calculated to be 65.7, 61.3, 61.9, 291.5, 57.1, and 76.3% for the glucosides of cyanidin, delphinidin, malvidin, peonidin, petunidin, and its sum (referred to as total anthocyanins), respectively. Bioequivalence was established for none of the anthocyanins. On a low level, urinary excretion of anthocyanins was fast, and the excretion rates seem to exhibit monoexponential characteristics over time after ingestion of both red grape juice and red wine. Due to low bioavailability, any significant contribution of anthocyanins to health protecting properties of red wine or red grape juice seems questionable, but the clinical relevance of these findings awaits further investigation.

Administration, Oral↗